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The transmission line circuit model of the Z machine is used extensively to aid in the design and analysis of experiments conducted on Z. The circuit model consists of both 1-D and 2-D networks of transmission lines modeling Z's 36 pulselines, vacuum insulator stack, MITLs, vacuum convolute, and load [1].

As the last command-triggered switch in the Refurbished Z accelerator at Sandia National Laboratories (SNL), the laser-triggered gas switch (LTGS) system is instrumental in the overall performance of Z and allows for flexibility in pulse shaping for various experimental campaigns. It is desirable to push the operating envelope of the switch to higher voltages and currents to allow for a higher peak power to be delivered to the load while at the same time reducing jitter and pre-fire rate for increased precision and reliability. We have accomplished this in a version of the LTGS that we call the C1.1 with the constraint of keeping the overall switch size consistent with physical space available. The C1.1 LTGS consists of laser-triggered and cascade portions which has been reported on previously.[1] However, the C1.1 eliminates the trigger plate and supports the cascade section in a cantilevered fashion. Improvements to this iteration of the LTGS were mainly mechanical in nature. Other minor electrical improvements were made to reduce regions of electric field enhancement and to reduce the likelihood of tracking by adding scalloping to the center support rod. Materials choice for the center support rod was important due to both the mechanical and electrical requirements placed on this component. Mechanical shock testing of the improved switch was performed on a shaker table available at SNL prior to installation on Z and showed that the improvements resulted in less displacement of the cantilevered end and less rotation of components in the cascade section. All electrical testing of the improved LTGS was performed on the Z machine. To date, we have accumulated 377 shots on C1.1 switches without a pre-fire. Runtime statistics are determined after each shot and show that the C1.1 switches are very tolerant to voltage and pressure variations exhibiting median runtimes of 43.9 ns with a jitter (1-σ) of 5.4 ns for all switch closures. The modifications made to and the performance results of the improved LTGS system are detailed in this manuscript.

The modern high current, high voltage pulsed accelerators utilize vacuum-post-hole convolutes to add the current of a number of parallel self Magnetic Insulated Transmission Lines (MITL) to a single one located very close to the centrally located load. The reason of course of using several parallel MITL's to transfer the current pulse from large, ~1.5 m, radii to the 1-2 cm load is to reduce the transfer inductance. For example, the vacuum chamber of the 24-26-MA Z machine has a 1.45-m radius vacuum section containing four parallel conical MITLs merging into one 6cm radial disc MITL adjacent to the centrally located load via a double post-hole convolute array located at 7.62 cm from the axis. Although special care has been taken to reduce the electrical stresses on the cathode hole surfaces in order to avoid electron emission, substantial current losses, 4-6 MA, are observed most probably due to plasma formation and the unavoidable magnetic nulls. In the proposed experiments we will study the behavior of only one convolute using the MYKONOS-V driver. MYKONOS-V is a Linear Transformer Driver (LTD) voltage adder composed of 5 nominally 1-MA cavities connected in series. The voltage adder radial A-K cavity is deionized water insulated. The experimental set-up is designed in such a way to reach conditions on the convolute very similar to those existing on Z. Most importantly, in contrast to Z, it provides full view of the convolute for optical and spectroscopic imaging and gives the flexibility and freedom to study various options in an effort to reduce the convolute losses without affecting the day-to-day Z experiments. This is going to be a dedicated convolute study experiment. The hardware design, numerical simulations and proposed diagnostics will be presented and discussed.

Sandia National Laboratories' Z-Backlighter laser facility is using a laser driven monochromatic X-ray crystal imaging concept at the manganese He-alpha energy of 6.151 keV to backlight experiments for High Energy Density Physics (HEDP) on the `Z'-Facility, the world's most powerful pulsed power engine and X-ray source. To further improve the reliability and efficiency of this tool, a series of experiments has been performed to determine the system's sensitivity to parameter variations such as changes in target properties, pre-pulse levels, pre-pulse separation or pulse energy. In addition, an improved hardware set has been developed to enhance the precision and robustness of the target setup for transport between pre-alignment and final shot implementation.

A soft x-ray (0.1–1 keV) streak camera using a grazing-incidence mirror has been developed for the Sandia Z facility, a 20 MA, 100 ns rise-time accelerator that can generate >200 TW,2 MJ, x-ray pulses. The streak camera is used to measure with one dimension of spatial resolution the continuous time history of sub-kilo-electron-volts emission from z-pinch and radiation flow experiments. Radiation >1 keV is eliminated by the use of a grazing-incidence mirror and transmission filters. The diagnostic has a magnification of 1.22, a 20 mm field-of-view and a spatial resolution of ∼350 μm. The recording length of the instrument is variable in duration up to a maximum of 33 ns, making it well suited for the typical 100 ns Z pinch implosion times. The spatial resolution can readily be changed to be along either the axial or the radial direction.

We have developed, calibrated, and tested a high sensitivity neutron detector that can be operated in the harsh x-ray bremsstrahlung environment that exists in experiments conducted on the 20 MA Z z-pinch facility located at Sandia National Laboratories in Albuquerque, New Mexico. The detector uses a scintillator coupled to a microchannel-plate photomultiplier tube detector and extensive x-ray shielding.

A novel x-ray imager, which takes time-resolved gated images along a single line-of-sight, has been successfully implemented at the National Ignition Facility (NIF). This Gated Laser Entrance Hole diagnostic, G-LEH, incorporates a high-speed multi-frame CMOS x-ray imager developed by Sandia National Laboratories to upgrade the existing Static X-ray Imager diagnostic at NIF. The new diagnostic is capable of capturing two laser-entrance-hole images per shot on its 1024 × 448 pixels photo-detector array, with integration times as short as 1.6 ns per frame. Since its implementation on NIF, the G-LEH diagnostic has successfully acquired images from various experimental campaigns, providing critical new information for understanding the hohlraum performance in inertial confinement fusion (ICF) experiments, such as the size of the laser entrance hole vs. time, the growth of the laser-heated gold plasma bubble, the change in brightness of inner beam spots due to time-varying cross beam energy transfer, and plasma instability growth near the hohlraum wall.

Several magnetized liner inertial fusion (MagLIF) experiments have been conducted on the Z accelerator at Sandia National Laboratories since late 2013. Measurements of the primary DD (2.45 MeV) neutrons for these experiments suggest that the neutron production is thermonuclear. Primary DD yields up to 3e12 with ion temperatures ~2-3 keV have been achieved. Measurements of the secondary DT (14 MeV) neutrons indicate that the fuel is significantly magnetized. Measurements of down-scattered neutrons from the beryllium liner suggest ρRliner ~ 1g/cm2. Neutron bang times, estimated from neutron time-of-flight (nTOF) measurements, coincide with peak x-ray production. Furthermore, plans to improve and expand the Z neutron diagnostic suite include neutron burn-history diagnostics, increased sensitivity and higher precision nTOF detectors, and neutron recoil-based yield and spectral measurements.

A tentative schedule of experiments for the ignition campaign on the National Ignition Facility (NIF) has been developed. These experiments will be used to validate beam pointing and balance, to tune time history and symmetry of drive of NIF hohlraums, and to implode subignition and igniting targets. The initial target diagnostics are designed to validate beam pointing and to demonstrate the properties of the hohlraums.

We present a new diagnostic for the National Ignition Facility (NIF) [1,2]. The Streaked Polar Instrumentation for Diagnosing Energetic Radiation (SPIDER) is an x-ray streak camera for use on almost-igniting targets, up to ~10 17 neutrons per shot. It measures the x-ray burn history for ignition campaigns with the following requirements: X-Ray Energy 8-30keV, Temporal Resolution 10ps, Absolute Timing Resolution 30ps, Neutron Yield: 10 14 to 10 17 . The features of the design are a heavily shielded instrument enclosure outside the target chamber, remote location of the neutron and EMP sensitive components, a precise laser pulse comb fiducial timing system and fast streaking electronics. SPIDER has been characterized for sweep linearity, dynamic range, temporal and spatial resolution. Preliminary DT implosion data shows the functionality of the instrument and provides an illustration of the method of burn history extraction.

The implosions of initially solid beryllium liners (tubes) have been imaged with penetrating radiography through to stagnation. These novel radiographic data reveal a high degree of azimuthal correlation in the evolving magneto-Rayleigh-Taylor structure at times just prior to (and during) stagnation, providing stringent constraints on the simulation tools used by the broader high energy density physics and inertial confinement fusion communities. To emphasize this point, comparisons to 2D and 3D radiation magnetohydrodynamics simulations are also presented. Both agreement and substantial disagreement have been found, depending on how the liner's initial outer surface finish was modeled. The various models tested, and the physical implications of these models are discussed. These comparisons exemplify the importance of the experimental data obtained.

Aerial surveys of waterbirds were made on Lake Wyara (salt) and Lake Numalla (freshwater) in arid Australia, every three months, 1987-1989. These lakes were significant sites for conservation of waterbirds. Aerial counts were on average 42 000 waterbirds (2600-113 500), including at least 41 species. In March 1988, total numbers probably exceeded 280 000. More than half the population of freckled duck Stictonetta naevosa may occur on the lakes. Although only 3 km apart and similar in size, the salt lake had about ten times more waterbirds /mainly ducks, herbivores, small wading birds) than the freshwater lake (mainly piscivores, large wading birds). Differences in waterbird communities between the lakes were attributable to food resources. There were larger numbers of planktonic invertebrates and more macrophyte vegetation in the salt lake than in the freshwater lake while the freshwater lake contained fish and shrimp populations.

Two versions of a current driver for single-turn, single-use 1-cm diameter magnetic field coils have been built and tested at the Sandia National Laboratories for use with cluster fusion experiments at the University of Texas in Austin. These coils are used to provide axial magnetic fields to slow radial loss of electrons from laser-produced deuterium plasmas. Typical peak field strength achievable for the two-capacitor system is 50 T, and 200 T for the ten-capacitor system. Current rise time for both systems is about 1.7 {mu}s, with peak current of 500 kA and 2 MA, respectively. Because the coil must be brought to the laser, the driver needs to be portable and drive currents in vacuum. The drivers are complete but laser-plasma experiments are still in progress. Therefore, in this report, we focus on system design, initial tests, and performance characteristics of the two-capacitor and ten-capacitors systems. The questions of whether a 200 T magnetic field can retard the breakup of a cluster-fusion plasma, and whether this field can enhance neutron production have not yet been answered. However, tools have been developed that will enable producing the magnetic fields needed to answer these questions. These are a two-capacitor, 400-kA system that was delivered to the University of Texas in 2010, and a 2-MA ten-capacitor system delivered this year. The first system allowed initial testing, and the second system will be able to produce the 200 T magnetic fields needed for cluster fusion experiments with a petawatt laser. The prototype 400-kA magnetic field driver system was designed and built to test the design concept for the system, and to verify that a portable driver system could be built that delivers current to a magnetic field coil in vacuum. This system was built copying a design from a fixed-facility, high-field machine at LANL, but made to be portable and to use a Z-machine-like vacuum insulator and vacuum transmission line. This system was sent to the University of Texas in Austin where magnetic fields up to 50 T have been produced in vacuum. Peak charge voltage and current for this system have been 100 kV and 490 kA. It was used this last year to verify injection of deuterium and surrogate clusters into these small, single-turn coils without shorting the coil. Initial test confirmed the need to insulate the inner surface of the coil, which requires that the clusters must be injected through small holes in an insulator. Tests with a low power laser confirmed that it is possible to inject clusters into the magnetic field coils through these holes without destroying the clusters. The university team also learned the necessity of maintaining good vacuum to avoid insulator, transmission line, and coil shorting. A 200-T, 2 MA system was also constructed using the experience from the first design to make the pulsed-power system more robust. This machine is a copy of the prototype design, but with ten 100-kV capacitors versus the two used in the prototype. It has additional inductance in the switch/capacitor unit to avoid breakdown seen in the prototype design. It also has slightly more inductance at the cable connection to the vacuum chamber. With this design we have been able to demonstrate 1 MA current into a 1 cm diameter coil with the vacuum chamber at air pressure. Circuit code simulations, including the additional inductance with the new design, agree well with the measured current at a charge voltage of 40 kV with a short circuit load, and at 50 kV with a coil. The code also predicts that with a charge voltage of 97 kV we will be able to get 2 MA into a 1 cm diameter coil, which will be sufficient for 200 T fields. Smaller diameter or multiple-turn coils will be able to achieve even higher fields, or be able to achieve 200-T fields with lower charge voltage. Work is now proceeding at the university under separate funding to verify operation at the 2-MA level, and to address issues of debris mitigation, measurement of the magnetic field, and operation in vacuum. We anticipate operation at full current with single-turn, magnetic field coils this fall, with 200 T experiments on the Texas Petawatt laser in the spring of 2012.

The LTD technological approach can result in very compact devices that can deliver fast, high current and high voltage pulses straight out of the cavity without any complicated pulse forming and pulse-compression network. Through multistage inductively insulated voltage adders, the output pulse, increased in voltage amplitude, can be applied directly to the load. Because the output pulse rise time and width can be easily tailored (pulse shaped) to the specific application needs, the load may be a vacuum electron diode, a z-pinch wire array, a gas puff, a liner, an isentropic compression load (ICE) to study material behavior under very high magnetic fields, or a fusion energy (IFE) target. Ten 1-MA LTD cavities were originally designed and built to run in a vacuum or Magnetic Insulated Transmission Line (MITL) voltage adder configuration and, after successful operation in this mode, were modified and made capable to operate assembled in a de-ionized water insulated voltage adder. Special care has been taken to de-aerate the water and eliminate air bubbles. Our motivation is to test the advantages of water insulation compared to the MITL transmission approach. The desired effect is that the vacuum sheath electron current losses and pulse front erosion would be avoided without any new difficulties caused by the de-ionized water insulator. Presently, we have assembled and are testing a two-cavity, water insulated voltage adder with a liquid resistor load. Experimental results of up to 95kV capacitor charging are presented and compared with circuit code simulations.

Few data exist on abundance and diversity of waterbirds on Lake Eyre in the arid zone of Australia. We report extremely high densities of waterbirds during a study over an eight-month period, August 1990–February 1991. At least thirty species were seen during aerial surveys, and nine previously unrecorded species were sighted on the lake. Numbers were highest in December when more than 300 000 waterbirds, including 135 000 shorebirds, were estimated. These figures were considered to underestimate true abundance by 50%. Australian pelicans Pelecanus conspicillatus (448 nests), silver gulls Larus novaehollandiae (4754 nests) and Caspian terns Hydroprogne caspia (about 80 nests) nested on one of the islands. Only silver gulls and Caspian terns were successful. Historical records indicate that some flooding of the lake bed occurs every year. These results show the importance of this wetland to waterbird conservation in Australia.

The first controlled experiments measuring the growth of the magneto-Rayleigh-Taylor instability in fast ($\ensuremath{\sim}100\text{ }\text{ }\mathrm{ns}$) Z-pinch plasmas are reported. Sinusoidal perturbations on the surface of an initially solid Al tube (liner) with wavelengths of $25--400\text{ }\text{ }\ensuremath{\mu}\mathrm{m}$ were used to seed the instability. Radiographs with $15\text{ }\text{ }\ensuremath{\mu}\mathrm{m}$ resolution captured the evolution of the outer liner surface. Comparisons with numerical radiation magnetohydrodynamic simulations show remarkably good agreement down to $50\text{ }\text{ }\ensuremath{\mu}\mathrm{m}$ wavelengths.

A 3D fully electromagnetic (EM) model of the principal pulsed-power components of a high-current linear transformer driver (LTD) has been developed. LTD systems are a relatively new modular and compact pulsed-power technology based on high-energy density capacitors and low-inductance switches located within a linear-induction cavity. We model 1-MA, 100-kV, 100-ns rise-time LTD cavities [A. A. Kim et al., Phys. Rev. ST Accel. Beams 12, 050402 (2009)PRABFM1098-440210.1103/PhysRevSTAB.12.050402] which can be used to drive z-pinch and material dynamics experiments. The model simulates the generation and propagation of electromagnetic power from individual capacitors and triggered gas switches to a radially symmetric output line. Multiple cavities, combined to provide voltage addition, drive a water-filled coaxial transmission line. A 3D fully EM model of a single 1-MA 100-kV LTD cavity driving a simple resistive load is presented and compared to electrical measurements. A new model of the current loss through the ferromagnetic cores is developed for use both in circuit representations of an LTD cavity and in the 3D EM simulations. Good agreement between the measured core current, a simple circuit model, and the 3D simulation model is obtained. A 3D EM model of an idealized ten-cavity LTD accelerator is also developed. The model results demonstrate efficient voltage addition when driving a matched impedance load, in good agreement with an idealized circuit model.

A three-dimensional, fully electromagnetic (EM) model of the principal pulsed-power components of a new high-current linear transformer driver (LTD) z-pinch accelerator has been developed. LTD systems are a relatively new modular compact pulsed-power technology based on high energy density capacitors and low-inductance switches packed around a parallel-plate disk feed. We model 1-MA, 100-kV, 100-ns rise-time LTD cavities developed for driving z-pinch loads1. The simulation model tracks the generation and propagation of electromagnetic power from individual capacitors through triggered gas switches driving a radially symmetric output line. Multiple cavities are combined for power multiplication that drives a water-filled coaxial transmission line. A fully EM 3D model of a single 1-MA 100-kV LTD cavity driving a simple resistive load is presented and compared to electrical measurements. A new model of the current loss through the ferromagnetic cores is developed for use both in circuit representations of an LTD cavity and in the 3D EM simulations. Good agreement between the measured core current, a simple circuit model, and the 3D simulation model is obtained. A 3D EM model of a 10 cavity LTD accelerator, presently under construction at Sandia National Laboratories, is also developed. The model results demonstrate efficient voltage addition when driving a matched impedance load, in good agreement with an idealized circuit model.

Sandia in collaborations with a number of other institutions, is developing a new paradigm in pulsed power technology: the Linear Transformer Driver (LTD) technology. This approach can provide very compact devices that can deliver very fast high current and high voltage pulses. The output pulse rise time and width can be easily tailored to the specific application needs. We have extensively tested several induction LTD flat doughnut-shaped cavities which are 3m in diameter and have a 1.8 m bore and only ∼20 cm thickness, but they can deliver 0.1 TW, 70 ns rise time pulses to a matched ∼ 0.1 Ohm load. Experiments with a 1 TW Inductive Voltage Adder (IVA), which includes 10, 1-MA LTD cavities connected in series, are in preparation at MYKONOS LTD Laboratory in Sandia National Laboratories, Albuquerque, NM. This MYKONOS voltage adder will be the first ever IVA built with a transmission line insulated with de-ionized water. We present the design and experimental results of the first two-cavity water isolated voltage adder with a liquid salt solution resistive load. This is the first step towards the assembly of a ten cavity voltage adder.

The Linear Transformer Driver (LTD) technology can provide very compact devices that deliver very fast high current and high voltage pulses. The output pulse rise time and width can be easily tailored to the specific application needs. Trains of large number of high current pulses can be produced with variable inter-pulse separation from nanoseconds to microseconds. Most importantly these devices can be rep-rated to frequencies only limited by the capacitor specifications that usually is 10Hz. To date we have completed the experimental evaluation of two (LTD I, LTD II) 500-kA cavities in both single and rep-rated modes. A larger 1-MA cavity was tested in a single shot mode and in a voltage adder configuration. The first built inductively isolated 1-MA LTD Voltage Adder (IVA) was composed of five cavity connected in series with a vacuum insulated transmission line. It was tested with both resistive and electron diode loads. The experimental results are in excellent agreement with numerical simulations. Experiments with a 1 TW Inductive Voltage Adder (IVA), which includes ten, 1-MA LTD cavities connected in series, are in preparation at Mykonos LTD Laboratory in Sandia National Laboratories, Albuquerque, NM. This time around the Mykonos voltage adder will be built with a transmission line insulated with deionized water. In this experimental work we aim to test the advantages of water insulation as compared to self Magnetic Insulated Transmission Line transport (MITL). It is hoped that the vacuum sheath electron current losses will be avoided without any new difficulties caused by the deionized water. This voltage adder will be rep-rated at 6 shots per minute. In the present paper we briefly present the LTD cavity architecture, describe the two LTD cavity types built and experimentally tested in single and rep-rated modes and present the design of the first two-cavity water insulated voltage adder with a liquid salt solution resistive load. This is the first step towards the assembly of a ten-cavity voltage adder of which most of the components are already built and/or fully designed.

There has been significant progress in the past few years in the development and application of Terawatt-class pulsed power generators. Sandia's flagship is the Z facility, which was recently refurbished to improve its energy, power (∼100 TWe), reliability, and precision. We are now routinely performing one shot per day, obtaining load currents as high as 26 MA to create high magnetic fields (> 1000 Tesla) and pressures (10s of Mbar). In a z-pinch configuration, the magnetic pressure (Lorentz Force) supersonically implodes a plasma created from a cylindrical wire array or liner, which at stagnation generates a plasma with energy densities as high as 10 MJ/cm3 and temperatures exceeding 1 keV at 0.1% of solid density. These plasma implosions can produce over 2 MJ of x-ray energy at powers greater than 200 TW for Inertial Confinement Fusion (ICF), radiation hydrodynamics, radiation-material interaction, Inertial Fusion Energy (IFE), and astrophysics experiments. In an alternate configuration, the large magnetic pressure is used to directly drive Isentropic Compression Experiments (ICE) to pressures greater than 6 Mbar or accelerate flyer plates to velocities as high as 45 km/s for equation of state experiments at pressures as high as 20 Mbar. This research and development is performed in collaboration with many other research groups from large laboratories and universities around the world. This paper summarizes research performed with Z and more recently with the refurbished Z facility, advances in high-photon-energy radiography, derivative applications of the pulsed power program, and advances in the science of pulsed power that could revolutionize the next-generation facilities.

The magneto-Rayleigh-Taylor (MRT) instability is ubiquitous to pinch plasmas compressed by magnetic pressure, and is an important factor in determining whether a cylindrical liner can reach the axis in a relatively intact form. While there are many RT characterization experiments, there are few well-characterized MRT experiments and none for fast (∼100 ns) z-pinch implosions in which the magnetic pressure typically quickly dominates over material strength. We will present data from our initial two campaigns to study the growth of MRT instabilities.

A reliable sodium wire‐array z‐pinch load has been developed for use on the Saturn accelerator. This load routinely produces implosions with ≥200 GW of power in the heliumlike sodium 1s2–1s2p 1P1 line at 11 A. Our best shots have used a 12.5‐mm‐diam, 20‐mm‐long annular array of 16 75‐μm‐diam pure sodium wires. This load will allow us to test predictions of gain in the sodium/neon resonant photoexcitation x‐ray laser system.

We demonstrate a rubidium-ion laser with two strong laser lines at 17.3 and 17.6 nm. The lasing transitions are 3p → 3s transitions in Ne-like rubidium. Gains of 1.9 and 1.4 cm−1 are measured for these two lines, respectively. This weak gain, as compared with that in other Ne-like laser systems, is ascribed to both the surface roughness of the target and the dilution associated with using rubidium chloride salt. In addition, three weaker lasing transitions are observed, including the anomalous J = 0 → 1 transition at 16.5 nm.

An optical surface of variable concave parabolic shape and a clear aperture of 30 mm was created using two rings to deform a flat 50.8 mm diameter mirror. The deformable mirror assembly was modeled using finite element analysis software as well as analytical solutions. Measured parabolic surface deformation showed good agreement with those models. Mirror performance was quantitatively studied using an interferometer and focal lengths from hundreds of meters down to the meter scale have been achieved. In this publication, the deformable mirror has been applied to compensate on shot thermal lensing in 16 mm diameter and 25 mm diameter Nd:Phosphate glass rod amplifiers by using only a single actuator. The possibility to rapidly change focal lengths across two to three orders of magnitude has applications for remote sensing, such as laser induced breakdown spectroscopy, LIDAR, and control of laser filament formation.

Recent experiments have shown that interactions of intense ultrafast lasers with targets of small DD clusters with hundreds to thousands of atoms can produce very high ion temperature plasmas and produce DD fusion neutrons1. Because ion temperatures exceeding 10 keV are achievable it is possible to produce high fusion yields even with laser pulses of a few joules to a few hundred joules. The fusion yield in these experiments is limited by the fast disassembly time (≪100 ps) of the small, hot laser-produced deuterium plasma. Enhancement of fusion neutron yield might be achieved if plasma confinement could be improved by the introduction of an external magnetic field, even if for only a few nanoseconds. At the densities of these plasmas (∼ 1019 /cm3), magnetic fields of 100 to 200 T are needed to slow plasma expansion sufficiently to enhance neutron yield. Because magnetic pressures exceed the yield strength of almost materials at these field levels it is necessary to design a system based on disposable, single-use, single-turn coils. The current required to drive these coils ranges from 1 to 2 MA, depending on coil diameter. Such parameters are similar to a driver at the National High Magnetic Field Laboratory2. However, a driver for this application must be transportable with a sufficiently small footprint that it can be placed near the output of the laser.

Sandia is actively pursuing the development of new accelerators based on the new technology of the Linear Transformer Driver (LTD). LTD based drivers are currently considered for many applications including x-ray radiography, very high current Z-pinch drivers, and Z-pinch IFE (Inertial Fusion Energy). LTD is a new method for constructing high-current, high-voltage induction pulsed accelerators. The pulse forming capacitors and switches are enclosed inside the accelerating cavity. High currents can be achieved by feeding each cavity core with many capacitors connected in parallel in a circular array. High voltage is obtained by inductively adding the output voltage of many cavities in series. Utilizing the presently available capacitors and switches we can envision building the next generation of fast radiographic and Z-pinch drivers without large Marx generators and voluminous oil-water pulse forming and pulse compression networks. One of the most significant advantages is that the LTD drivers can be rep-rated. The latter makes LTD the driver of choice for z pinch IFE. Presently we have in rep-rated operation in Sandia a one 0.1-MA, 100-kV LTD cavity. In parallel we are preparing a new LTD laboratory to house our 10, 1-MA, 100-kV LTD cavities recently constructed and received from the HCEI, Tomsk, Russia.

Sandia National Laboratories is investigating linear transformer driver (LTD) architecture as a potential replacement of conventional Marx generator based pulsed power systems. Such systems have traditionally been utilized as the primary driver for z-pinch wire-array experiments, radiography, inertial fusion energy (IFE) concepts, and dynamic materials experiments (i.e. ICE).

In this article we present the design and test results of the most powerful, fast linear transformer driver (LTD) stage developed to date. This 1-MA LTD stage consists of 40 parallel RLC (resistor R, inductor L, and capacitor C) circuits called ``bricks'' that are triggered simultaneously; it is able to deliver $\ensuremath{\sim}1\text{ }\text{ }\mathrm{MA}$ current pulse with a rise time of $\ensuremath{\sim}100\text{ }\text{ }\mathrm{ns}$ into the $\ensuremath{\sim}0.1\mathrm{\text{\ensuremath{-}}}\mathrm{Ohm}$ matched load. The electrical behavior of the stage can be predicted by using a simple RLC circuit, thus simplifying the designing of various LTD-based accelerators. Five 1-MA LTD stages assembled in series into a module have been successfully tested with both resistive and vacuum electron-beam diode loads.

The linear transformer driver (LTD) is a new method for constructing high current, high-voltage pulsed accelerators. The salient feature of the approach is switching and inductively adding the pulses at low voltage straight out of the capacitors through low inductance transfer and soft iron core isolation. Sandia National Laboratories are actively pursuing the development of a new class of accelerator based on the LTD technology. Presently, the high current LTD experimental research is concentrated on two aspects: first, to study the repetition rate capabilities, reliability, reproducibility of the output pulses, switch prefires, jitter, electrical power and energy efficiency, and lifetime measurements of the cavity active components; second, to study how a multicavity linear array performs in a voltage adder configuration relative to current transmission, energy and power addition, and wall plug to output pulse electrical efficiency. Here we report the repetition rate and lifetime studies performed in the Sandia High Current LTD Laboratory. We first utilized the prototype � 0:4-MA, LTD I cavity which could be reliably operated up to � 90-kV capacitor charging. Later we obtained an improved 0.5-MA, LTD II version that can be operated at � 100 kV maximum charging voltage. The experimental results presented here were obtained with both cavities and pertain to evaluating the maximum achievable repetition rate and LTD cavity performance. The voltage adder experiments with a series of double sized cavities (1 MA, � 100 kV) will be reported in future publications.

We demonstrate that a wide variety of current-pulse shapes can be generated using a linear-transformer-driver (LTD) module that drives an internal water-insulated transmission line. The shapes are produced by varying the timing and initial charge voltage of each of the module’s cavities. The LTD-driven accelerator architecture outlined in [Phys. Rev. ST Accel. Beams 10, 030401 (2007)PRABFM1098-440210.1103/PhysRevSTAB.10.030401] provides additional pulse-shaping flexibility by allowing the modules that drive the accelerator to be triggered at different times. The module output pulses would be combined and symmetrized by water-insulated radial-transmission-line impedance transformers [Phys. Rev. ST Accel. Beams 11, 030401 (2008)PRABFM1098-440210.1103/PhysRevSTAB.11.030401].

Systems Engineering has, as a primary objective, th e imperative to provide systems that meet performance requirements while adhering to program schedule and cost constraints . Conventional programmatic risk analysis methodologies rely on in-depth knowledge of internal program risk factors, which, if known, are often only accessible to a select few within the program. Others who have a stake in the expected performance of the project are thus unable to accurately estimate and predict cost and schedule. One way to address this issue is to utilize historical cost and schedule pe rformance data for similar programs to estimate future performance of a current program. Using this approach, a methodology was developed to estimate the likely cost growth of cur rent fighter programs by comparing them to past US defense programs. This methodology offers the ability to estimate expected cost and schedule growth by placing a program in a historical context of past defense acquisition programs. The methodology was enabled by a database of historical program cost and schedule information. The development of normalization techniques and examples of the application of this methodology are presented. No s ingle analysis method or relationship appeared to be conclusively best; however, together the analyses provided a reasonable range of cost growth estimates. The methodology can be applied by Systems Engineers across a wide range of programs at any stage in their life cycle, correlating their progress to date, and enabling estimates of future performance costs and schedules, and associated risks.

In the presentation we present a survey of the application driven development of new high-current (25+ MA), fast risetime (~ 100 ns) pulsed-power technology at the Sandia National Laboratories (SNL), but this paper only focuses on megagauss magnetic field driver development in order to preserve first-publication rights for the co-authors with the other technologies. Thus in the presentation we note that the Z accelerator has fired nearly 200 shots since the upgrade, and is now being operated at 4 to 5 shots per week. Initial failures after the upgrade have been resolved with improvements in the 6-MV laser-triggered switches, the oil water barriers, and the insulator stack. With the upgrade Z is also able to produce tailored current profiles for isentropic compression of materials using staggered timing of the laser triggered switches. We also describe the Linear Transformer Driver (LTD) technology that is being investigated as a potential follow-on pulsed power technology for the design of the next larger machine that has a high repetition-rate (up to 0.1 Hz) capability. Ten 1-MA LTD modules have been fabricated and are being setup as a 1 MV, 1 MA sub-module prototype. A lower-current, more compact LTD design is also being tested for radiography applications. For both of these designs 200-kV, 25-kA gas switches are being developed and tested to both increase switch lifetime and to minimize cost. A compact, portable, 2-MA, 2 μsec driver, which we describe in this paper, is being developed to drive single-turn magnetic field coils for laser-plasma experiments in vacuum. (4 pages)

Experiments are described in which a high‐purity, high‐power (0.15 TW, 1 MeV) proton beam is generated from an ion source consisting of H2 gas frozen onto a liquid‐helium‐cooled copper anode at 4.2 K in a series‐field‐coil extraction diode on the 0.7 TW HydraMITE‐II accelerator. Peak anode proton current densities of 2 kA/cm2 were measured. This current density is a factor of 100 higher than those obtained in previous liquid‐helium‐cooled cryogenic diode experiments on small accelerators and is in the range required for high‐power ion beam applications. Thomson parabola, Faraday cup, and carbon activation measurements indicate an ion beam proton fraction close to 100% for the cryogenic source, compared to 50–70% for the standard hydrocarbon anode tested. The cryogenic proton source is believed to consist of no more than a few monolayers of molecular hydrogen. The hydrogen‐coated cryogenic anode shows a faster initial anode turn‐on than other materials. However, source‐limited emission from the thin hydrog...

This article reports the experimental characterization of a z-pinch driven-vacuum hohlraum. The authors have measured soft x-ray fluxes of 5 x 10{sup 12} W/cm{sup 2} radiating from the walls of hohlraums which are 2.4--2.5 cm in diameter by 1 cm tall. The x-ray source used to drive these hohlraums was a z-pinch consisting of a 300 wire tungsten array driven by a 2 MA, 100 ns current pulse. In this hohlraum geometry, the z-pinch x-ray source can produce energies in excess of 800 kJ and powers in excess of 100 TW to drive these hohlraums. The x-rays released in these hohlraums represent greater than a factor of 25 in energy and more than a factor of three in x-ray power over previous laboratory-driven hohlraums.

An instrument is described which can obtain x-ray spectral power measurements utilizing the diffraction pattern produced when x rays pass through a slit. Traditionally, these types of measurements yielding low to moderate spectral resolution have been made with filtered x-ray diodes or with a transmission grating. The instrument described below has several advantages over filtered x-ray diodes in determining the spectral power profile such as an insensitivity to surface contamination. In addition, this instrument does not require the use of filters which can be destroyed during a shot making absolute measurements difficult and very time consuming. The advantages over a transmission grating system include cost, mechanical robustness, and fewer components which require spectral calibration.

We have developed a system of differential-output monitors that diagnose current and voltage in the vacuum section of a 20-MA 3-MV pulsed-power accelerator. The system includes 62 gauges: 3 current and 6 voltage monitors that are fielded on each of the accelerator's 4 vacuum-insulator stacks, 6 current monitors on each of the accelerator's 4 outer magnetically insulated transmission lines (MITLs), and 2 current monitors on the accelerator's inner MITL. The inner-MITL monitors are located 6 cm from the axis of the load. Each of the stack and outer-MITL current monitors comprises two separate $B$-dot sensors, each of which consists of four 3-mm-diameter wire loops wound in series. The two sensors are separately located within adjacent cavities machined out of a single piece of copper. The high electrical conductivity of copper minimizes penetration of magnetic flux into the cavity walls, which minimizes changes in the sensitivity of the sensors on the 100-ns time scale of the accelerator's power pulse. A model of flux penetration has been developed and is used to correct (to first order) the $B$-dot signals for the penetration that does occur. The two sensors are designed to produce signals with opposite polarities; hence, each current monitor may be regarded as a single detector with differential outputs. Common-mode-noise rejection is achieved by combining these signals in a $50\mathrm{\text{\ensuremath{-}}}\ensuremath{\Omega}$ balun. The signal cables that connect the $B$-dot monitors to the balun are chosen to provide reasonable bandwidth and acceptable levels of Compton drive in the bremsstrahlung field of the accelerator. A single $50\mathrm{\text{\ensuremath{-}}}\ensuremath{\Omega}$ cable transmits the output signal of each balun to a double-wall screen room, where the signals are attenuated, digitized ($0.5\mathrm{\text{\ensuremath{-}}}\mathrm{ns}/\mathrm{sample}$), numerically compensated for cable losses, and numerically integrated. By contrast, each inner-MITL current monitor contains only a single $B$-dot sensor. These monitors are fielded in opposite-polarity pairs. The two signals from a pair are not combined in a balun; they are instead numerically processed for common-mode-noise rejection after digitization. All the current monitors are calibrated on a 76-cm-diameter axisymmetric radial transmission line that is driven by a 10-kA current pulse. The reference current is measured by a current-viewing resistor (CVR). The stack voltage monitors are also differential-output gauges, consisting of one 1.8-cm-diameter $D$-dot sensor and one null sensor. Hence, each voltage monitor is also a differential detector with two output signals, processed as described above. The voltage monitors are calibrated in situ at 1.5 MV on dedicated accelerator shots with a short-circuit load. Faraday's law of induction is used to generate the reference voltage: currents are obtained from calibrated outer-MITL $B$-dot monitors, and inductances from the system geometry. In this way, both current and voltage measurements are traceable to a single CVR. Dependable and consistent measurements are thus obtained with this system of calibrated diagnostics. On accelerator shots that deliver 22 MA to a low-impedance $z$-pinch load, the peak lineal current densities at the stack, outer-MITL, and inner-MITL monitor locations are 0.5, 1, and $58\text{ }\text{ }\mathrm{MA}/\mathrm{m}$, respectively. On such shots the peak currents measured at these three locations agree to within 1%.

There is a need to generate magnetic fields both above and below 1 megagauss (100 T) with compact generators for laser-plasma experiments in the Beamlet and Petawatt test chambers for focused research on fundamental properties of high energy density magnetic plasmas. Some of the important topics that could be addressed with such a capability are magnetic field diffusion, particle confinement, plasma instabilities, spectroscopic diagnostic development, material properties, flux compression, and alternate confinement schemes, all of which could directly support experiments on Z. This report summarizes a two-month study to develop preliminary designs of magnetic field generators for three design regimes. These are, (1) a design for a relatively low-field (10 to 50 T), compact generator for modest volumes (1 to 10 cm3), (2) a high-field (50 to 200 T) design for smaller volumes (10 to 100 mm3), and (3) an extreme field (greater than 600 T) design that uses flux compression. These designs rely on existing Sandia pulsed-power expertise and equipment, and address issues of magnetic field scaling with capacitor bank design and field inductance, vacuum interface, and trade-offs between inductance and coil designs.

X-ray production by imploding wire-array Z pinches is studied using radiation magnetohydrodynamics simulation. It is found that the density distribution created by ablating wire material influences both x-ray power production, and how the peak power scales with applied current. For a given array there is an optimum ablation rate that maximizes the peak x-ray power, and produces the strongest scaling of peak power with peak current. This work is consistent with trends in wire-array Z pinch x-ray power scaling experiments on the Z accelerator.

In this paper, we explore magnetized liner inertial fusion (MagLIF) [S. A. Slutz et al., Phys. Plasmas 17, 056303 (2010)] using a semi-analytic model [R. D. McBride and S. A. Slutz, Phys. Plasmas 22, 052708 (2015)]. Specifically, we present simulation results from this model that: (a) illustrate the parameter space, energetics, and overall system efficiencies of MagLIF; (b) demonstrate the dependence of radiative loss rates on the radial fraction of the fuel that is preheated; (c) explore some of the recent experimental results of the MagLIF program at Sandia National Laboratories [M. R. Gomez et al., Phys. Rev. Lett. 113, 155003 (2014)]; (d) highlight the experimental challenges presently facing the MagLIF program; and (e) demonstrate how increases to the preheat energy, fuel density, axial magnetic field, and drive current could affect future MagLIF performance., Comment: Published in Physics of Plasmas [http://dx.doi.org/10.1063/1.4939479]

Accurate modeling of load behavior in Z‐pinch plasma radiation sources driven by high‐current generators requires the measurement of fast‐rise‐time multimegampere currents close to the load. Conventional current diagnostics mounted in inductive cavities (such as B‐dot loops and Rogowski coils) fail at small radius because of electrical breakdown produced by high dI/dt. In this paper, we describe the use of large‐signal, nanosecond‐time‐resolution lithium niobate piezoelectric stress gauges to directly measure the magnetic pressure B2/2μ0=μ0I2/8π2r2 generated at radius r by a current I flowing in a radial transmission line. Current measurements have been performed at radius r=2.54×10−2 m on Sandia National Laboratories’ Proto‐II (10 TW) and SATURN (30 TW) gas puff Z‐pinch experiments with maximum currents of 10.1 MA and dI/dt to 2.1×1014 A/s. Comparisons with Faraday rotation and B‐dot current diagnostic measurements at large radius are presented. Bremsstrahlung noise problems unique to the SATURN gas puff...

Short-implosion-time 20-mm diameter, 300-wire tungsten arrays maintain high peak x-ray powers despite a reduction in peak current from 19 to 13 MA. The main radiation pulse on tests with a 1-mm on-axis rod may be explained by the observable $\stackrel{\ensuremath{\rightarrow}}{j}\ifmmode\times\else\texttimes\fi{}\stackrel{\ensuremath{\rightarrow}}{B}$ work done during the implosion, but bare-axis tests require sub-mm convergence of the magnetic field not seen except perhaps in $g1$ keV emission. The data include the first measurement of the imploding mass density profile of a wire-array $Z$ pinch that further constrains simulation models.

Summary form only given. Compact nested tungsten wire arrays operating in current transfer mode produce peak soft x-ray powers of 200 to 250 TW on the Z accelerator. Such arrays use outer (inner) array diameters of 20 (12) mm and also employ low density, 4 to 6 mm diameter CH2 foam pulse shaping targets on the axis. These are among the highest powers produced on Z, at any array diameter. Optimized single tungsten wire arrays produce peak powers of 160 TW at 20 mm diameter. These nested arrays also produce the narrowest x-ray bursts of any arrays on Z (1.9 to 2.5 ns) compared to 4 to 7 ns with single arrays. X-ray radiography at 6.151 keV is used to determine the mass density profile as a function of space and time. The density profiles are obtained from the radiographs via Abel inversion. These data indicate that the narrowing of the x-ray pulse of nested arrays is correlated to a narrowing of the measured spatial width of the mass distribution at the axis near stagnation. The nested mass distribution narrows as a result of three factors: (1) Current transfer mode operation allows the Magneto-Rayleigh-Taylor (MRT) perturbation and wavelength to be reset to smaller values at the time of current transfer to the inner array, consistent with an ablation phase of the inner wire array. The wavelength and amplitude of the outer array is not impressed on the inner at switching. The MRT wavelength and perturbation is reduced by a factor of ~3.4 compared to a single wire array when compared at the same implosion radius. (2) Current transfer mode allows the outer array mass to fill the interior of the inner wire array. Thus the MRT growth on the inner wire array is stabilized by mass accretion. (3) Finally, low-density axial foam targets also change the mass profile near the axis and further narrow the pulse through mass accretion. Such optimized nested arrays may permit a peak power of 100 TW in 5 ns width from a 10-mm diameter array. This more compact array would be compatible with driving a scale-0.6 double-ended hohlraum ICF concept, which would permit pulsed-power ignition with fusion yields of 50 MJ at half of the required facility energy storage of the scale-1.0 double-ended hohlraum design (400 MJ yields).

Summary form only given. The radiation power and energy produced by 20 mm diameter, 300-wire tungsten arrays of various masses was studied on the 20 MA, 100 ns Z pulsed power facility. On some tests, 1-mm diameter Al rods were inserted on the axis of the array both to limit the convergence and to reduce possible sources of magnetic kinetic energy. Empirical estimates of the kinetic energy of the implosion were made using x-ray pinhole camera and streak images, transmission-grating- spectrometers, and 6151 eV radiography. These were compared to the energy radiated before and during the main power pulse, which is the portion relevant for inertial confinement fusion applications, as well as the total energy radiated from the Z-pinch. It is clear that the total energy radiated by these wire arrays requires energy input above and beyond the kinetic energy of the implosion, as noted elsewhere for Al arrays, The energy radiated during the main power pulse (generally about half of the total radiated energy) is close to the estimated implosion kinetic energy for the heavy arrays studied here, but for the lightest arrays there may be some discrepancies. Specifically, the size of the X-ray emitting regions measured with three independent diagnostic methods appears too large to be consistent with the high convergence ratios required to explain the main pulse radiation energy. Supporting analyses of a mass-density profile obtained via radiography and circuit model energetics are ongoing at the time of this abstract, as well as an error analysis to understand whether we can conclusively support the statement that a non-kinetic source of energy is required to explain the main radiation pulse.

On the first inertial-confinement-fusion ignition facility, the target capsule will be DT filled through a long, narrow tube inserted into the shell. microg-scale shell perturbations Delta m' arising from multiple, 10-50 microm-diameter, hollow SiO2 tubes on x-ray-driven, ignition-scale, 1-mg capsules have been measured on a subignition device. Simulations compare well with observation, whence it is corroborated that Delta m' arises from early x-ray shadowing by the tube rather than tube mass coupling to the shell, and inferred that 10-20 microm tubes will negligibly affect fusion yield on a full-ignition facility.

We have developed an accelerator architecture that can serve as the basis of the design of petawatt-class $z$-pinch drivers. The architecture has been applied to the design of two $z$-pinch accelerators, each of which can be contained within a 104-m-diameter cylindrical tank. One accelerator is driven by slow ($\ensuremath{\sim}1\text{ }\ensuremath{\mu}\mathrm{s}$) Marx generators, which are a mature technology but which necessitate significant pulse compression to achieve the short pulses ($\ensuremath{\ll}1\text{ }\ensuremath{\mu}\mathrm{s}$) required to drive $z$ pinches. The other is powered by linear transformer drivers (LTDs), which are less mature but produce much shorter pulses than conventional Marxes. Consequently, an LTD-driven accelerator promises to be (at a given pinch current and implosion time) more efficient and reliable. The Marx-driven accelerator produces a peak electrical power of 500 TW and includes the following components: (i) 300 Marx generators that comprise a total of $1.8\ifmmode\times\else\texttimes\fi{}{10}^{4}$ capacitors, store 98 MJ, and erect to 5 MV; (ii) 600 water-dielectric triplate intermediate-store transmission lines, which also serve as pulse-forming lines; (iii) 600 5-MV laser-triggered gas switches; (iv) three monolithic radial-transmission-line impedance transformers, with triplate geometries and exponential impedance profiles; (v) a 6-level 5.5-m-diameter 15-MV vacuum insulator stack; (vi) six magnetically insulated vacuum transmission lines (MITLs); and (vii) a triple-post-hole vacuum convolute that adds the output currents of the six MITLs, and delivers the combined current to a $z$-pinch load. The accelerator delivers an effective peak current of 52 MA to a 10-mm-length $z$ pinch that implodes in 95 ns, and 57 MA to a pinch that implodes in 120 ns. The LTD-driven accelerator includes monolithic radial transformers and a MITL system similar to those described above, but does not include intermediate-store transmission lines, multimegavolt gas switches, or a laser trigger system. Instead, this accelerator is driven by 210 LTD modules that include a total of $1\ifmmode\times\else\texttimes\fi{}{10}^{6}$ capacitors and $5\ifmmode\times\else\texttimes\fi{}{10}^{5}$ 200-kV electrically triggered gas switches. The LTD accelerator stores 182 MJ and produces a peak electrical power of 1000 TW. The accelerator delivers an effective peak current of 68 MA to a pinch that implodes in 95 ns, and 75 MA to a pinch that implodes in 120 ns. Conceptually straightforward upgrades to these designs would deliver even higher pinch currents and faster implosions.

Six major accidents covering the gamut of systems and conditions from railroad and airplane to mining and nuclear are examined for cause and effect, as determined by their investigating teams’ results, and some common threads are found. The manner in which Results Oriented Analysis can be used to define the capabilities that must be in place for future mitigation of associated risks is shown, for the general category of catastrophic occurrences. A general risk assessment methodology using Results Oriented Analysis is outlined. I. Introduction TILISATION of Results Oriented Analysis under various guises (e.g. Effects Based Planning) has come into vogue for planning purposes in the past few years, particularly in the USA Military. Prior to this, Risk Assessment and Risk Management were the “buzz” methodologies for USA Department of Defence (DoD) projects. Heretofore, neither of these techniques has been forwarded as being useful with the other, particularly in a safety context. In this paper, a method of combining them for just such purposes is described. The method is based on a set of general risk areas related to systems safety. These general areas are in turn related to the common threads established for the accidents discussed in the paper. Major catastrophic accidents to complex systems such as the Space Shuttle Columbia disintegration in January of 2003, the historic Shuttle Challenger failure in 1986, and the Japanese nuclear Tokaimura incident in 1999, typically give rise to a hue and cry asking “How could this have happened?” After lengthy investigations by illustrious Boards of Inquiry, the answers come back, frequently with the conclusion that “this was one of a kind”, unusual conditions, etc. etc. In this paper several major systems “catastrophes” are examined. Several had comprehensive investigation reports available, with detailed analyses and findings. Others had only a news reporter’s account of what people in a position to know were saying about what and why the accident had happened. In each of the cases examined, although there were many differences in the causes attributed to the accidents, there were also common threads. This paper does not attempt to establish a statistically significant result, but rather, to show that in several noteworthy cases there does appear to be significant correlation. To paraphrase Feynman (1), if the real correlation is not so small, accident cases would show similarities of troubles, near failures, and possible actual failures with a reasonable number of cases. In this paper six of these cases are discussed: 1. The Space Shuttle Challenger failure 2. The Longford Gas explosion 3. The Tokaimura Nuclear Reactor incident 4. The Kianga Mining explosion 5. The London Tube derailment 6. The Columbia Space Shuttle disintegration In some of the investigations of these accidents, recommendations were made in the interest of preventing future occurrences. These also have a common thread, which can be expressed as establishing specific conditions for moving from one conditional state to a better conditional state.

In situ single shot peak intensity has been calibrated to be 1.25×1017Wcm-2/J energy at the ultra-intense focus of a multi-joule laser pulse using optical field ionization of high charge states of inert gases.

Imaging systems that include a specific source, imaging concept, geometry, and detector have unique properties such as signal-to-noise ratio, dynamic range, spatial resolution, distortions, and contrast. Some of these properties are inherently connected, particularly dynamic range and spatial resolution. It must be emphasized that spatial resolution is not a single number but must be seen in the context of dynamic range and consequently is better described by a function or distribution. We introduce the "dynamic granularity" G(dyn) as a standardized, objective relation between a detector's spatial resolution (granularity) and dynamic range for complex imaging systems in a given environment rather than the widely found characterization of detectors such as cameras or films by themselves. This relation can partly be explained through consideration of the signal's photon statistics, background noise, and detector sensitivity, but a comprehensive description including some unpredictable data such as dust, damages, or an unknown spectral distribution will ultimately have to be based on measurements. Measured dynamic granularities can be objectively used to assess the limits of an imaging system's performance including all contributing noise sources and to qualify the influence of alternative components within an imaging system. This article explains the construction criteria to formulate a dynamic granularity and compares measured dynamic granularities for different detectors used in the X-ray backlighting scheme employed at Sandia's Z-Backlighter facility.