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A compact pulse forming line (CPFL) concept based on a folded transmission line and high-breakdown strength dielectric was explored through an effort combining proof-of-principle experiments with electromagnetic modeling. A small-scale folded CPFL was fabricated using surface-mount ceramic multilayer capacitors. The line consisted of 150 capacitors close-packed in parallel and delivered a 300 ns flat-top pulse. The concept was carried to a 10 kV class device using a polymer-ceramic nanocomposite dielectric with a permittivity of 37.6. The line was designed for a 161 ns FWHM length pulse into a matched load. The line delivered a 110 ns FWHM pulse, and the pulse peak amplitude exceeded the matched load ideal. Transient electromagnetic analysis using the particle-in-cell code ICEPIC was conducted to examine the nature of the unexpected pulse shortening and distortion. Two-dimensional analysis failed to capture the anomalous behavior. Three-dimensional analysis replicated the pulse shape and revealed that the bends were largely responsible for the pulse shortening. The bends not only create the expected reflection of the incident TEM wave but also produce a non-zero component of the Poynting vector perpendicular to the propagation direction of the dominant electromagnetic wave, resulting in power flow largely external to the PFL. This analysis explains both the pulse shortening and the amplitude of the pulse.

The performance of a high-gain FCG is often limited by internal electrical breakdown caused by the high voltage generated during operation. Modern diagnostic techniques provide the opportunity to diagnose internal breakdowns so that generator designs can be improved. This paper describes the internal breakdowns observed in the JAKE FCG developed at the AFRL during the late 1990's. A revision to the stator winding pattern of the JAKE generator has led to improved control of the internal voltage. Designated JILL, the revised generator has substantially better flux transport efficiency, particularly at higher seed current. The techniques employed to design the new stator winding and the results of development testing are presented.

Pegasus II is the upgraded version of Pegasus, a pulsed power machine used in the Los Alamos Above Ground Experiments (AGEX) program. The goal of the program is to produce an intense (>100 TW) source of soft x‐rays from the thermalization of the KE of a 1 to 10 MJ collapsing plasma source. The radiation pulse should have a maximum duration of several tens of nanoseconds and will be used in the study of fusion conditions and material properties. This paper addresses z‐pinch experiments done on a capacitor bank where the radiating plasma source is formed by an imploding annular aluminum foil driven by the JxB forces generated by the current flowing through the foil.

The seismic response of liquid-filled cylindrical storage tanks has been investigated using finite element techniques implemented in the general purpose structural analysis computer code ANSYS. Both added mass concepts and displacement-based fluid finite elements were employed to allow for the effects of the liquid. Simplified response spectrum modal analyses of a tank making use of the axisymmetric harmonic displacement patterns of the principal modes of deformation were found to give accurate predictions of the tank behaviour with a rigidly anchored base. Time history analyses of three-dimensional finite element models of unanchored and flexibly anchored tanks, with gap conditions between the tank base and the supporting floor to allow lift-off of the base, indicated that stresses in the tank and resultant loads on the floor can be much greater than for a rigidly restrained tank. These results demonstrate the importance of carefully considering the restraint conditions when performing seismic design calculations on storage tanks.

An annular electron beam with less than 30 mrad of angular velocity spread, a radius of 1 cm, and a current density exceeding 0.4 MA/cm2 has been generated with a magnetized foilless diode. The diode current loss is limited to less than a few percent by careful design of the tapered transition region connecting a self‐magnetically insulated vacuum transmission line to the externally magnetized foilless diode. Details of the transition section design and operating characteristics of the electron beam generator are given.

A mixed antiglobulin procedure has been developed to provide simultaneous study of cell surface immunoglobulin and detailed cytological features in Giemsa stained preparations. The percentage of surface immunoglobulin bearing lymphocytes, monocytes and granulocytes changed dramatically when lymphocytes were incubated at 37 degrees C, or following sheep erythrocyte rosette enrichment procedures.

The theory of an optical parametric oscillator located internal to the cavity of the pump laser has recently been presented by Oshman and Harris. An oscillator of this type has been constructed and the details of its operation are presented here. Several features predicted by the theory have been observed; in particular a form of relaxation oscillation peculiar to the internal oscillator has been observed for the first time. In addition to the experimental results the question of the stability of the various modes of operation and factors affecting the pulse repetition rate of the pulsing solution are considered.

We report observations of heating of a dense (∼1017 cm−3) plasma using a 3‐MeV electron beam with a current density of 5×105 A/cm2. The measured, strong dependence of heating on beam transverse temperature and the short saturation distance (

This Letter reports new observations of resonances in a low-density plasma column and a quantitative theory of the frequency spectrum which is in excellent agreement with these measurements. Other measurements have recently been reported by Dattner. (1)

The Gemini two beam CO2 laser fusion system incorporates a complex optical system with nearly 100 surfaces per beam, associated with the generation, transport and focusing of CO2 laser beams for irradiating laser fusion targets. Even though the system is nominally diffraction limited, in practice the departure from the ideal situation drops the Strehl ratio to 0.24. This departure is caused mostly by the imperfections in the large (34 cm optical clear aperture diameter) state-of-the-art components like the sodium chloride windows and micromachined mirrors. While the smaller optical components also contribute to this degradation, the various possible misalignments and nonlinear effects are considered to contribute very little to it. Analysis indicates that removing the static or quasi-static errors can dramatically improve the Strehl ratio. A deformable mirror which can comfortably achieve the design goal Strehl ratio of ≥ 0.7 is described, along with the various system trade-offs in the design of the mirror and the control system.

As the only well developed laser system potentially suitable for a laser fusion power system, it is critical that the feasibility of fusion induced by CO2 laser pulses be demonstrated. For the next 2 years (until the 10-kJ 8-beam system at LASL becomes operational), the principal tool for carrying out these investigations will be the Dual Beam Laser System (DBLS). Designed primarily as a prototype for the four modules that will comprise the 10-kJ laser system, DBLS has been upgraded to an experimental target facility by the addition of a high-contrast short-pulse oscillator and the necessary target diagnostic and handling equipment. With target experiments scheduled to begin in the spring of 1976, the DBLS is currently undergoing evaluation to establish its short-pulse performance characteristics.

on results that illustrate the importance of wall ablation. Section 111 develops a simple model of a plasma armature incorporating wall ablation. The model is applied first to the analysis of a constant current railgun to show how ablation affects railgun behavior and then to the experimental data of Section 11. Section IV develops an extension to the simple ablation model that includes viscous drag on the arc plasma. Again comparisons with the data of Section I1 support the inclusion of viscous drag as an important process in railguns. Finally, in Section V the future of plasma armature railguns is examined with particular emphasis on scaling to large devices and techniques to eliminate Parametric measurements have been performed on a plasma armature railgun at Las Alamos. The railgun is extensively instrumented for studies of the projectile motion and its interaction with the plasma armature. The most important parameter, driving current, was varied from 100 kA to 400 kA. Additional parameters investigated include current waveform, injection velocity, injection gas, wall insulation material, and initial pressure. For all combinations of parameters investigated, the measured performance was substantially below theoretical or control the ablation process. predictions. A strong correlation was found between performance loss and abnormal plasma armature features such as multiple arc formation, or separation of the armature from the projectile. In extreme cases, the plasma armature was observed to come to rest inside the railgun. A plasma armature model has been developed which successfully accounts for the measured performance loss and for many of the abnormal plasma armature features. By incorporating the ablation of wall material into the armature plasma thismodel predictstwo parasitic forces that dominate the motion of the armature at high velocity. One force is the inertial drag term mav. The other is frictional drag between the hot, turbulent plasma and the walls, which increases as m,v2. Simple scaling relations, which incorporate the plasma I. Experimental Apparatus The experimental results reported below were obtained with the HYVAX Phase I (HYVAX-I) railgun. The HYVAX railgun is a high performance modular device designed for distributed operation. It has a design length of 13 m and a theoretical velocity capability of 25 km/s at a design current of 500 kA. HYVAX-I consists of two 1.22 m long barrel modules and three 0.30 m long current connection modules from the H W A X device. The modules are assembled as a single stage railgun with an effective lenmh of2.5 m. A cross section ofthe barrel is shown ~ armature model, rho; that velocities >IO km/s wil l he ex. tremely dificult to achieve with plasma armature railguns unless the effects ofablation are eliminated or carefull, controlled.

A quantitative theory of resonance oscillations, such as observed by Dattner and others, is given. The first two moments of the collisionless Boltzmann equation assuming a scalar pressure are used in conjunction with a physically reasonable radial electron density profile to describe the oscillations of a hot nonuniform plasma cylinder. These equations coupled with Maxwell's equations assuming a scalar potential are solved numerically to yield the frequency spectrum of the plasma wave resonances. It is found that the frequency spectrum depends on the parameter r/w2/ where rw is the radius of the plasma column and is the mean square Debye length of the electron plasma. New experimental observations of dipole and quadrupole spectra for two plasma columns of differing radii are reported and the results of these observations are in good agreement with the theory. The physical mechanism of the resonances is described.