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The goal of the National Direct-Drive Program is to demonstrate and understand the physics of laser direct drive (LDD). Efforts are underway on OMEGA for the 100-Gbar Campaign to demonstrate and un...

This paper presents the design of a flexure-based mount allowing adjustment in three rotational degrees of freedom (DOFs) through high-precision set-screw actuators. The requirements of the applica...

Here, a cryogenic target positioning system was designed and installed on the National Ignition Facility (NIF) target chamber. This instrument incorporates the ability to fill, form, and characterize the NIF targets with hydrogen isotopes needed for ignition experiments inside the NIF target bay then transport and position them in the target chamber. This effort brought to fruition years of research in growing and metrologizing high-quality hydrogen fuel layers and landed it in an especially demanding operations environment in the NIF facility. D-T (deuterium-tritium) layers for NIF ignition experiments have extremely tight specifications and must be grown in a very highly constrained environment: a NIF ignition target inside a cryogenic target positioner inside the NIF target bay. Exquisite control of temperature, pressure, contaminant level, and thermal uniformity are necessary throughout seed formation and layer growth to create an essentially-groove-free single crystal layer.

The U.S. Department of Energy has embarked on a campaign to conduct credible fusion ignition experiments on the National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory in 2010. The target assembly specified for this campaign requires the formation of a deuterium-tritium fuel ice layer in a 2-mm-diam capsule at the center of a 9-mm-long X 5-mm-diam cylinder, called a hohlraum. The ice layer must be formed and maintained at temperatures below 20 K. At laser shot time, the target is positioned at the center of the NIF target chamber, aligned to the laser beams, and held stable to

A single quartz crystal microbalance (QCM) is cooled to 18 K to measure condensation rates inside of a retractable shroud enclosure. The shroud is designed to minimize condensate on fusion targets ...

A central feature of an Inertial Fusion Energy (IFE) power plant is a target that has been compressed and heated to fusion conditions by the energy input of the driver. The technology to economical...

A central feature of an inertial fusion energy (IFE) power plant is a target that has been compressed and heated to fusion conditions by the energy input of the driver. This is true whether the driver is a laser system, heavy ion beams or Z-pinch system. The IFE target fabrication, injection and tracking programmes are focusing on methods that will scale to mass production. We are working closely with target designers, and power plant systems specialists, to make specifications and material selections that will satisfy a wide range of required and desirable target characteristics. One-of-a-kind capsules produced for today’s inertial confinement fusion experiments are estimated to cost about US$2500 each. Design studies of cost-effective power production from laser and heavy-ion driven IFE have suggested a cost goal of about $0.25–0.30 for each injected target (corresponding to ∼10% of the ‘electricity value’ in a target). While a four orders of magnitude cost reduction may seem at first to be nearly impossible, there are many factors that suggest this is achievable. This paper summarizes the design, specifications, requirements and proposed manufacturing processes for the future for laser fusion, heavy ion fusion and Z-pinch driven targets. These target manufacturing processes have been developed—and are proposed—based on the unique materials science and technology programmes that are ongoing for each of the target concepts. We describe the paradigm shifts in target manufacturing methodologies that will be needed to achieve orders of magnitude reductions in target costs, and summarize the results of ‘nth-of-a-kind’ plant layouts and cost estimates for future IFE power plant fuelling. These engineering studies estimate the cost of the target supply in a fusion economy, and show that costs are within the range of commercial feasibility for electricity production.

Fueling of a commercial Inertial Fusion Energy (IFE) power plant consists of supplying about 500,000 fusion targets each day. The most challenging type of target in this regard is for laser-driven, direct drive IFE. Spherical capsules with cryogenic DT fuel must be injected into the center of a reaction chamber operating at temperatures as high as 1500 °C and possibly containing as much as 0.5 Torr of xenon fill gas. The DT layer must remain highly symmetric, have a smooth inner ice surface finish, and reach the chamber center at a temperature of about 18.5 K. This target must be positioned at the center of the chamber with a placement accuracy of ±5 mm. The accuracy of alignment of the laser driver beams and the target in its final position must be within ±20 μm. All this must be repeated six times per second. The method proposed to meet these requirements is injecting the targets into the reaction chamber at high speed (∼400 m/s), tracking them, and hitting them on the fly with steerable driver beams. The challenging scientific and technological issues associated with this task are being addressed through a combination of analyses, modeling, materials property measurements, and demonstration tests with representative injection equipment. Measurements of relevant DT properties are planned at Los Alamos National Laboratory. An experimental target injection and tracking system is now being designed to support the development of survivable targets and demonstrate successful injection scenarios. Analyses of target heating are underway. Calculations have shown that the direct drive target must have a highly reflective outer surface to prevent excess heating by thermal radiation. In addition, heating by hot chamber fill gas during injection far outweighs the thermal radiation. It is concluded that the dry-wall, gas-filled reaction chambers must have gas pressures less than previously assumed in order to prevent excessive heating in the current direct drive target designs. An integrated power plant systems study to address this issue has been initiated.

Space flight affects many physiologic systems, and one of these is vision and ocular health. Radiation exposure, cephalad shifts of body fluid, spacecraft cabin and spacesuit gas mixtures, and the space flight food system can all contribute to ocular changes during flight. These stressors contribute to an increased risk of cataracts among astronauts, and changes in vision accompanied by ophthalmic changes such as optic disc edema, globe flattening, hyperopic shifts, choroidal folds, and cotton wool spots have recently been observed in astronauts after long-duration space flight. The etiology of the refractive and structural ophthalmic changes is not known and continues to be researched; however, biochemical evidence indicates that the folate- and vitamin B12-dependent one-carbon transfer pathway may be involved. This chapter reviews the available literature on this topic, along with planned research to understand and counteract these effects.

Fuelling of a commercial inertial fusion energy (IFE) power plant consists of supplying about 500 000 fusion targets each day. The most challenging type of target in this regard is that for laser driven direct drive IFE power plants. Spherical capsules with cryogenic DT fuel must be injected into the centre of a reaction chamber operating at temperatures as high as 1500° C and possibly containing as much as 0.5 torr of xenon fill gas. The DT layer must remain highly symmetric, have a smooth inner ice surface finish and reach the chamber centre (CC) at a temperature of about 18.5 K. This target must be positioned at the centre of the chamber with a placement accuracy of ±5 mm. The accuracy of alignment of the laser driver beams and the target in its final position must be within ±20 μm. All this must be repeated six times per second. The method proposed to meet these requirements is to inject the targets into the reaction chamber at high speed ( ≈ 400 m/s), track them, and hit them in flight with steerable driver beams. The challenging scientific and technological issues associated with this task are being addressed through a combination of analyses, modelling, materials property measurements and demonstration tests with representative injection equipment. Measurements of relevant DT properties are planned at Los Alamos National Laboratory. An experimental target injection and tracking system is now being designed to support the development of survivable targets and demonstrate successful injection scenarios. Analyses of target heating are under way. Calculations have shown that a direct drive target must have a highly reflective outer surface to prevent excess heating by thermal radiation. In addition, heating by hot chamber fill gas during injection far outweighs that by the thermal radiation. It is concluded that the dry wall, gas filled reaction chambers must have gas pressures and wall temperatures less than previously assumed in order to prevent excessive heating in current direct drive target designs. An integrated power plant systems study to address this issue has been initiated.

We describe designs of hohlraums and capsules for both ignition (∼1–10 MJ) and high yield (up to ∼200 MJ) Z-pinch driven indirect-drive ICF concepts. Two potential Z-pinch hohlraum configurations –...

A high-resolution neutron spectroscopic technique is used to measure momentum-resolved magnon lifetimes in the prototypical two- and three-dimensional antiferromagnets Rb2MnF4 and MnF2, over the full Brillouin zone and a wide range of temperatures. We rederived theories of the lifetime resulting from magnon-magnon scattering, thereby broadening their applicability beyond asymptotically small regions of wavevector and temperature. Corresponding computations, combined with a small contribution reflecting collisions with domain boundaries, yield excellent quantitative agreement with the data., 5 pages, 4 figures

We describe a high pressure cryogenic fill station and a novel method to retrieve and transport filled inertial confinement fusion targets at cryogenic temperatures. The fill station (currently under construction) will be capable of filling millimeter-size plastic spheres with DT or D 2 to pressures exceeding 150 MPa. After filling, the thin-walled targets are cooled and kept below 20 K to prevent them from bursting. After cooling the targets, a cryogenic wrench is used to open the pressurization cell. The fill station cryostat is designed to allow a second cryostat to retrieve the filled targets. This second cold transfer cryostat features removable shrouds with seals that can be repeatably made and broken at cryogenic temperatures.

Azurite, a natural mineral made up of CuO chains, is also an intriguing spin-1/2 quantum magnet. There has been much debate as to the one-dimensional (1D) nature of this material by theorists and experimentalists alike. The focus of this debate lies in the interactions between Cu ions within the antiferromagnetically ordered state below 1.9 K. We present high-resolution inelastic neutron-scattering data that highlight the complexity of the magnetic ground state of azurite. The application of magnetic fields and temperatures were used to probe the excitations revealing important information about the dynamics in this system. From this we are able to conclude that the 1D Heisenberg antiferromagnetic spin chain model is not sufficient to describe the dynamics in azurite. Instead additional coupling including interchain interactions and an anisotropic staggered field are necessary to fully model the observed excitations.

Here we present neutron diffraction results on the mineral azurite. We have found that the crystal structure of azurite can be described in the space group $P{2}_{1}$, which is the next symmetric group below $P{2}_{1}/c$, as found in earlier works. This small change in symmetry does not greatly influence the lattice parameters or atomic fractional coordinates, which are presented here for single-crystal diffraction refinements. The ordered magnetic moment structure of this material has been determined and is comprised of two inequivalent magnetic moments on copper sites of magnitude $0.684(14)$ and $0.264(16){\ensuremath{\mu}}_{B}$. This result is discussed in terms of the anisotropic exchange and Dzyaloshinskii-Moriya interactions. It is found that the system is likely governed by one-dimensional behavior despite the long-range-ordered ground state. We also highlight the significance of strain in this material, which is strongly coupled to the magnetism.

We demonstrate the hohlraum radiation temperature and symmetry required for ignition-scale inertial confinement fusion capsule implosions. Cryogenic gas-filled hohlraums with 2.2 mm-diameter capsules are heated with unprecedented laser energies of 1.2 MJ delivered by 192 ultraviolet laser beams on the National Ignition Facility. Laser backscatter measurements show that these hohlraums absorb 87% to 91% of the incident laser power resulting in peak radiation temperatures of T(RAD)=300 eV and a symmetric implosion to a 100 μm diameter hot core.

Azurite, ${\text{Cu}}_{3}{({\text{CO}}_{3})}_{2}{(\text{OH})}_{2}$, has been considered an ideal example of a one-dimensional diamond chain antiferromagnet. Early studies of this material imply the presence of an ordered antiferromagnetic phase below ${T}_{N}\ensuremath{\sim}1.9\text{ }\text{K}$ while magnetization measurements have revealed a 1/3 magnetization plateau. To the best of our knowledge, no corroborating neutron-scattering results have been published to confirm the ordered magnetic moment structure. We present recent neutron-diffraction results which reveal the presence of commensurate magnetic order in azurite which coexists with significant magnetoelastic strain. The latter of these effects may indicate the presence of spin frustration in zero applied magnetic field. Muon spin rotation reveals an onset of short-range order below 3 K and confirms long-range order below ${T}_{N}$.

This document summarizes the Indirect Drive Warm-Loaded Ignition Target design. These targets either use a fill tube or the capsule is strong enough to withstand the room temperature pressure of the DT fuel. Only features that affect the design of the NIF Cryogenic Target System (NCTS) are presented. The design presented is the current thinking and may evolve further. The NCTS should be designed to accommodate a range of targets and target scales, as described here. The interface location between the target and the NCTS cryostat is at the target base / gripper joint, the tamping gas gland/gland joint, and the electrical plug/receptacle joint.

General Atomics is designing and building the OMEGA Cryogenic Target System (Fig. 1) for the University of Rochester's Laboratory for Laser Energetics. The purpose of this system is to deliver millimeter sized polymer shell targets to the center of the target chamber for inertial confinement fusion experiments. Prior to insertion, these targets are filled to pressures as high as 1500 atm with hydrogen isotopes (DT), the gas is cryogenically condensed, and the condensed material is layered to form a uniform inner shell. GA has demonstrated the successful filling with D/sub 2/ of plastic targets to 1100 atm, cooling, and cold transport utilizing prototype equipment. In addition to proving the viability of the proposed fill process, the prototypes have led to significant equipment simplifications and process improvements for the University of Rochester system.

Boron neutron capture therapy (BNCT) is based on a nuclear capture reaction that occurs when boron-10, a stable isotope, is irradiated with low energy neutrons to produce high-energy alpha particles and recoiling lithium-7 nuclei. The purpose of the present study was to determine what urinary metabolites, if any, could be detected in patients with brain tumors who were given sodium borocaptate (BSH), a drug that has been used clinically for BNCT. BSH was infused intravenously over a 1-h time period at doses of 26.5, 44.1, or 88.2 mg/kg of body weight to patients with high-grade brain tumors. Electrospray ionization mass spectrometry has been used to investigate possible urinary metabolites of BSH. Chemical and instrument conditions were established to detect BSH and its possible metabolites in both positive and negative electrospray ionization modes. Using this methodology, boronated ions were found in patients' urine samples that appeared to be consistent with the following chemical structures: BSH sulfenic acid (BSOH), BSH sulfinic acid (BSO(2)H), BSH disulfide (BSSB), BSH thiosulfinate (BSOSB), and a BSH-S-cysteine conjugate (BSH-CYS). Although BSH has been used clinically for BNCT since the late 1960s, this is the first report of specific biotransformation products following administration to patients. Further studies will be required to determine both the biological significance of these metabolites and whether any of these accumulate in significant amounts in brain tumors.

Recent advances in the technology of fast pulsed electrical power and load design have led to growing interest in the use of z-pinch machines as x-ray sources for fusion applications.1 To achieve high yield, z-pinch machines require the use of cryogenic targets. These targets contain a spherical polymer capsule with a layer of solid deuterium-tritium (DT) on the inside wall. This DT layer is obtained by first permeation filling the capsule with high pressure DT gas at room temperature. The filled capsule is then cooled to approximately 19 K to solidify the DT. The uniform layer is created through a process called “beta layering,” which involves placing the capsule in a very uniform temperature environment and allowing the natural heating due to beta decay of the tritium to provide the thermal energy to redistribute the DT into a uniform layer. General Atomics has performed preconceptual design studies of a system designed to fill a target with DT, cool it down to cryogenic temperatures, and then insert it into a z-pinch chamber. The baseline system design uses a supercritical helium stream to cool the target. The helium is compressed by a room temperature compressor and cooled using both liquid nitrogen and liquid helium reservoirs. The cold supercritical helium then travels to the target through an umbilical tube several meters long. This umbilical allows the target to be at the center of the chamber while the cryogenic equipment is safely outside. This paper will describe the preconceptual design of a z-pinch cryogenic target system and present the supporting thermal analysis.

Intraocular pressure (IOP) has been found to increase during microgravity. After peaking in the first few hours of orbital flight, IOP slowly decreases to a level that is slightly elevated above baseline IOP's. These modest elevations in IOP do not require treatment. Just as in 1-G, a clinically significant elevation of IOP that occurred during spaceflight would require treatment. We are not aware of previous studies of the efficacy of IOP lowering agents under conditions of microgravity.This double-masked, placebo-controlled study measured the IOP's of 11 adult subjects (22 eyes) at baseline, preflight, and zero-gravity aboard the NASA KC-135 aircraft, and postflight. One eye of each of the subjects was treated with betaxolol hydrochloride ophthalmic solution 0.5%, while the contralateral eye was treated with normal saline placebo, for 7 d prior to parabolic flight. IOP's were measured by the Tono-Pen 2, a gravity independent tonometer.A modest, but statistically significant reduction of 2.4 mmHg in mean IOP was noted in betaxolol treated eyes at the time of preflight measurement. During zero-G, the mean IOP's of both betaxolol treated eyes and placebo treated eyes increased approximately 20% over preflight levels. Postflight IOP's were similar to preflight IOP's.The effect of betaxolol on the IOP of eyes treated with for 1 wk prior to exposure to microgravity was statistically significant, but may lack clinical significance in normal eyes. Further research needs to be done to determine the efficacy during microgravity of betaxolol and other agents, in subjects who have upper normal to slightly elevated IOP's at 1 G.

To report excellent and stable vision in an astronaut during space flight after bilateral cataract surgery with intraocular lenses.A 60-year-old physician mission specialist astronaut developed cataracts and underwent phacoemulsification with insertion of one-piece polymethylmethacrylate intraocular lenses that had 6-mm optics bilaterally. Several months later, he flew on a space shuttle mission. Ocular examinations were performed before and after the mission, and the patient was questioned about visual changes during flight.Ocular examinations demonstrated stable bilateral posterior chamber intraocular lenses. Our subject reported excellent vision during liftoff, 18 days of microgravity, changes in cabin pressure, and reentry.Results suggest that intraocular lenses are safe, effective, and well tolerated during space flight.

General Atomics is designing, testing and fabricating a system for supplying cryogenic targets for the University of Rochester’s OMEGA laser system. A prototype system has demonstrated the filling of 1 mm diameter, 3 μm wall plastic spheres to 111 MPa (1100 atm) with deuterium and then cooling to 18 K to condense the fuel. The production design must be capable of routinely filling and cooling targets with a 50/50 mix of deuterium and tritium and transferring them to a device which places the targets into the focus of 60 laser beams. This paper discusses the design and analysis of the production Fill/ Transfer Station cryostat. The cryostat has two major components, a fixed base and a removable dome. The joint between the base and the dome is similar to a bayonet fitting and is sealed by a room temperature elastomeric o-ring. Since the cryostat must be housed in a glovebox, its design is driven strongly by maintenance requirements. To reach the equipment inside the cryostat, the dome is simply unbolted and lifted. The inside of the cryostat is maintained at 16 K by a closed loop helium flow system. Gaseous helium at about 1.4 MPa (200 psi) flows through tubes which are brazed to the inner walls. Cooling is provided by several cryocoolers which are located external to the cryostat. Liquid nitrogen is used as a heat intercept and to precool the helium gas.

First results from the analysis of neutron image data collected on implosions of cryogenically layered deuterium-tritium capsules during the 2011-2012 National Ignition Campaign are reported. The data span a variety of experimental designs aimed at increasing the stagnation pressure of the central hotspot and areal density of the surrounding fuel assembly. Images of neutrons produced by deuterium–tritium fusion reactions in the hotspot are presented, as well as images of neutrons that scatter in the surrounding dense fuel assembly. The image data are compared with 1D and 2D model predictions, and consistency checked using other diagnostic data. The results indicate that the size of the fusing hotspot is consistent with the model predictions, as well as other imaging data, while the overall size of the fuel assembly, inferred from the scattered neutron images, is systematically smaller than models' prediction. Preliminary studies indicate these differences are consistent with a significant fraction (20%–25%) of the initial deuterium-tritium fuel mass outside the compact fuel assembly, due either to low mode mass asymmetry or high mode 3D mix effects at the ablator-ice interface.

Capsule implosions on the National Ignition Facility (NIF) [Lindl et al., Phys. Plasmas 11, 339 (2004)] are underway with the goal of compressing deuterium-tritium (DT) fuel to a sufficiently high areal density (ρR) to sustain a self-propagating burn wave required for fusion power gain greater than unity. These implosions are driven with a carefully tailored sequence of four shock waves that must be timed to very high precision in order to keep the DT fuel on a low adiabat. Initial experiments to measure the strength and relative timing of these shocks have been conducted on NIF in a specially designed surrogate target platform known as the keyhole target. This target geometry and the associated diagnostics are described in detail. The initial data are presented and compared with numerical simulations. As the primary goal of these experiments is to assess and minimize the adiabat in related DT implosions, a methodology is described for quantifying the adiabat from the shock velocity measurements. Results are contrasted between early experiments that exhibited very poor shock timing and subsequent experiments where a modified target geometry demonstrated significant improvement.

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