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High-Frequency Pulse Generator

Description: Introduction: "The purpose of this work was to develop a high-frequency pulse generator that could be used in conducting research on high-rate trigger pairs and scaler circuits. The need for an instrument of this type arose because there was no parallel commercial instrument having this type arose because there was no parallel commercial instrument having a pulse recurrence frequency over approximately 200,000 pulses per second."
Date: July 3, 1947
Creator: Ohmart, Philip E.
Partner: UNT Libraries Government Documents Department

Reference Flat Pulse Generator

Description: Introduction: A reference step-like pulse generator is described which has been developed at NBS. This generator can be used for accurately characterizing the step response of various kinds of trap ient recording equipment (oscilloscopes, waveform recorders, transient digitizers, etc.). Basic design principles are given as well as complete circuit diagrams and descriptions. An analysis of the output stage of the generator is presented together with the circuit models for developing a time-domain computer simulation program using extended- SCEPTRE. Preliminary specifications indicate that the NBS Reference Flat Pulse Generator provides a negative-going reference transition duration (90 to 10 percent) of 600 ps, *20 percent with baseline perturbations of less than *2 percent for less than 5 ns.
Date: October 1983
Creator: Andrews, J. R.; Bell, B. A. & Baldwin, E. E.
Partner: UNT Libraries Government Documents Department

DVD Based Integrated Electronic Pulser

Description: The DVD based integrated pulser combines the storage capacity and simplicity of DVD technology with commonly available electronic components to build a relatively inexpensive yet highly capable testing instrument. DVD technology has matured to the mass consumer level and has found widespread acceptance in many scientific, industrial, and consumers sectors. Coupling the removable media and relatively large data capacity with a simple electronic readout allows this device to be easy to build, export and authenticate. Since there are few parts and the heart of the device is a mass consumer item the duplication cost is very low.
Date: March 30, 2004
Creator: Hughes, Michael A.; Kouzes, Richard T.; Morris, Scott J.; Pitts, W. K.; Pratt, Rick M. & Robinson, Eric E.
Partner: UNT Libraries Government Documents Department

Driving pockels cells using avalanche transistor pulsers

Description: The purpose of this paper is to describe the current state of avalanche transistor based Pockels cell driver development at LLNL and to provide the reader with a set of useful design guidelines. A general description of the units is followed by a short section on the circuit design of avalanche transistor pulsers. A more detailed design guide is given. Techniques for delivering either {1/4} or {1/2} wave voltages to a Pockels cell are covered. Recently these units have been modified for use at repetition rates up to 10kHz. Operating at high repetition rates represents problems for both the driver and the Pockels Cell. Design solutions for the pulser are presented as well as discussion of Pockels cell acoustic resonance.
Date: May 28, 1997
Creator: Fulkerson, E. S.; Norman, D. C. & Booth, R.
Partner: UNT Libraries Government Documents Department

Modeling and analysis of the high energy liner experiment, HEL-1

Description: A high energy, massive liner experiment, driven by an explosive flux compressor generator, was conducted at VNIIEF firing point, Sarov, on August 22, 1996. We report results of numerical modeling and analysis we have performed on the solid liner dynamics of this 4.0 millimeter thick aluminum liner as it was imploded from an initial inner radius of 236 mm onto a Central Measuring Unit (CMU), radius 55 mm. Both one- and two-dimensional MHD calculations have been performed, with emphasis on studies of Rayleigh-Taylor instability in the presence of strength and on liner/glide plane interactions. One-dimensional MHD calculations using the experimental current profile confirm that a peak generator current of 100-105 MA yields radial liner dynamics which are consistent with both glide plane and CMU impact diagnostics. These calculations indicate that the liner reached velocities of 6.9-7.5 km/s before CMU impact. Kinetic energy of the liner, integrated across its radial cross-section, is between 18-22 MJ. Since the initial goal was to accelerate the liner to at least 20 MJ, these calculations are consistent with overall success. Two-dimensional MHD calculations were employed for more detailed comparisons with the measured data set. The complete data set consisted of over 250 separate probe traces. From these data and from their correlation with the MHD calculations, we can conclude that the liner deviated from simple cylindrical shape during its implosion. Two-dimensional calculations have clarified our understanding of the mechanisms responsible for these deformations. Many calculations with initial outer edge perturbations have been performed to assess the role of Rayleigh-Taylor instability. Perturbation wavelengths between 4-32 mm and amplitudes between 8-240 {mu}m have been simulated with the experimental current profiles. When strength is omitted short wavelengths are observed to grow to significant levels; material strength stabilizes such modes in the calculations.
Date: August 1, 1997
Creator: Faehl, R.J.; Sheehey, P.T. & Reinovsky, R.E.
Partner: UNT Libraries Government Documents Department

Experiments on planar plasma flow switches at Los Alamos

Description: The authors have performed a series of experiments on the Colt facility at Los Alamos to study the performance of plasma flow switches and to understand the important physics issues which affect that performance. These experiments were done in planar geometry on a small machine to allow for better diagnostic access and a higher repetition rate. The Colt facility is a capacitor bank which stores 300 kJ at maximum charge and produced a peak current of 1.1 MA in 2.0 microseconds for these experiments. The diagnostics used for these experiments included an array of b-dot probes, visible framing pictures, visible spectroscopy, and laser interferometry. Characteristics of the switch are determined from spatial and temporal profiles of the magnetic field and the spatial profile and temperature of the switch plasma. Here the authors present results from experiments for a variety of switch conditions.
Date: December 1997
Creator: Benage, J. F., Jr.; Wysocki, F. J.; Bowers, R. & Oona, H.
Partner: UNT Libraries Government Documents Department

Pulse voltage circuits

Description: The problems associated with very high voltages may be avoided in part by a variety of pulse-multiplication techniques. These methods are quite varied but share two features, the use of modest dc voltages and the use of switching techniques, to produce in some manner a vectorial transient addition of voltages. Many such methods exist, but only the Marx blank, spiral generator, inversion generator, and Blumlein will be addressed here in detail. Two other methods will be given a brief discussion as matters of interest.
Date: January 1, 1980
Creator: Willis, W.L.
Partner: UNT Libraries Government Documents Department

Stripline magnetic modulators for lasers and accelerators

Description: The basics of magnetic modulators including magnetic element and circuit considerations as applied to accelerators and lasers requiring repetitive (1 to 10 kHz), high voltage (50 to 500 kV), short pulse (50 to 100 ns) are discussed. The scaling of energy losses and switching parameters with material are included.
Date: January 1, 1981
Creator: Nunnally, W.C.
Partner: UNT Libraries Government Documents Department

Design of a 20-MJ coaxial generator

Description: A design is presented for an explosive-driven sweeping-wave coaxial generator. The generator is required to deliver 20 MJ to a 10-nH load with a final current-doubling time of 10 ..mu..s. A simple model of the armature motion takes into account both the explosive drive and the back pressure of the magnetic field. Shock and diffusion losses are combined in a self-consistent manner with the armature dynamics to give a circuit model for the generator. The scaling of this design to higher energies is discussed.
Date: January 1, 1983
Creator: Felber, F.S.; Caird, R.S.; Fowler, C.M.; Erickson, D.J.; Freeman, B.L. & Coforth, J.H.
Partner: UNT Libraries Government Documents Department

Conceptual design for a short-pulse explosive-driven generator

Description: A design is described for a short-pulse explosive-driven generator. The initial flux is provided by a side-fed one-turn coil that is crow-barred at peak field. This field is then compressed by the axially uniform expansion of a cylindrical armature inside the coil. A multistrand helical coil is used to convert the changing flux to voltage at the coaxial output. The circuit is completed by the impact of the armsture against contact rings connected to the helical coil and output. An approximate circuit model is derived. The analysis indicates that several megajoules can be delivered to an inductive load in 0.5 to 5.0 ..mu..s.
Date: January 1, 1986
Creator: Caird, R.S. & Fowler, C.M.
Partner: UNT Libraries Government Documents Department

Neutrino horn power supply operational experience

Description: The operational experiences required to run the 300 kA pulsed power supply at Brookhaven National Laboratory are given. Various interlocks and monitoring circuits are described and the impact on system reliability are discussed. The initial conditioning process of the power supply during startup is described.
Date: January 1, 1987
Creator: Stillman, P.; Sandberg, J.; Carroll, A.S.; Leonhardt, W.; Monaghan, R.; Pearson, C. et al.
Partner: UNT Libraries Government Documents Department

Understanding High Voltage Vacuum Insulators for Microsecond Pulses

Description: High voltage insulation is one of the main areas of pulsed power research and development since the surface of an insulator exposed to vacuum can fail electrically at an applied field more than an order or magnitude below the bulk dielectric strength of the insulator. This is troublesome for applications where high voltage conditioning of the insulator and electrodes is not practical and where relatively long pulses, on the order of several microseconds, are required. Here we give a summary of our approach to modeling and simulation efforts and experimental investigations for understanding flashover mechanism. The computational work is comprised of both filed and particle-in-cell modeling with state-of-the-art commercial codes. Experiments were performed in using an available 100-kV, 10-{micro}s pulse generator and vacuum chamber. The initial experiments were done with polyethylene insulator material in the shape of a truncated cone cut at +45{sup o} angle between flat electrodes with a gap of 1.0 cm. The insulator was sized so there were no flashovers or breakdowns under nominal operating conditions. Insulator flashover or gap closure was induced by introducing a plasma source, a tuft of velvet, in proximity to the insulator or electrode.
Date: August 15, 2007
Creator: J.B., J; D.A., G; T.L., H; E.J., L; R.D., S; L.K., T et al.
Partner: UNT Libraries Government Documents Department

High Voltage Pulsar For 184-inch Cyclotron Electric Deflector

Description: This paper describes a high voltage pulse generator developed to deflect the beam of the 184-inch cyclotron at Berkeley, California. The apparatus develops a deflecting potential of 200 kilovolts that rises from 10% to 90% of peak value in 0.1 microseconds. The unit employs two similar 100 kilovolt water cooled pulse transformers connected symmetrically about ground to the electric deflector bars. Water-cooled General Electric pulse capacitors are discharged through the two turn primary windings of the pulse transformers by triggering a battery of 16 paralleled Kuthe 5022 hydrogen thyratrons. Output voltages are developed across the 17 turn secondary winding of the pulse transformer. The transformer is mounted in an oil filled lucite case that provides both insulation and compact design.
Date: April 24, 1948
Creator: Kerns, Q.A.; Baker, W.R.; Edwards, R.F. & Farly, G.M.
Partner: UNT Libraries Government Documents Department

NOTE ON TRANSISTORS FOR AVALANCHE-MODE OPERATION

Description: We have found that selected Motorola transistors of the MM-486, MM-487, and MM-488 type are quite useful for avalanche-mode operation. Figure 1 shows a circuit used in conjunction with a traveling-wave oscilloscope for selecting avalanche units. The output of the line-type pulse generator is 40 to 60 volts (either polarity of output pulse is available), and the rise time is less than 0.5 nsec. Figure Z shows a plot of the static V-I characteristics of the collector-to-emitter junction for various units, avalanching and nonavalanching. A transistor that avalanches will do 80 over the entire flat portion of the V-I characteristic. One can expect that 10 to 30% of the transistors will avalanche. There is some indication that the low-beta type (MM-486) give the best yield. There is a time delay of a few nanoseconds between application of a trigger pulse and the rise of the main avalanche current. Figures 3 and 4 shows this delay, measured between the 50% point of the trigger-voltage waveform and the 50% point of the avalanche output waveform, as a function of trigger-voltage amplitude (Fig. 3) and static-collector current (Fig. 4). The negative-resistance region (such as that in Fig. 2) should be avoided if time and amplitude jitter of the output pulse are to be minimized. A temperature change from 70 to 150 F has negligible effect on time delay, but raises the breakdown knee (Fig. 2) to higher current (e. g., from 2 x 10{sup -3} to 8 x 10{sup -3} {micro}a).
Date: March 1, 1962
Creator: Miller, Harold W. & Kerns, Quentin A.
Partner: UNT Libraries Government Documents Department

SPARK-GAP-TRIGGER AMPLIFIER

Description: Short over-all time delay, low time jitter, and excellent long-term reliability are among the desirable features designed into a pulse generator that produces a 2-MW output pulse 30 nsec after the application of a 1-V signal at its 50-ohm input connector. The 10-kV output pulse can be used to trigger simultaneously several spark gaps of the type used in spark-chamber pulse modulators. The 10{sup 8} power gain of the spark-gap-trigger amplifier is achieved by four stages of amplification packaged in a 5-1/4 inch rack-mount chassis that operates directly from a 117-V line. The individual stages, each selected to give minimum time delay for a given power gain at their respective power levels are: avalanche transistors, planar triode, grounded-grid planar triode, and a triggered-spark gap. The techniques used for the last stage, a spark gap triggered by a corona light, are of particular interest since the same techniques are applicable to obtaining short time delays and long-term reliability from the larger spark gaps that the amplifier was designed to trigger. During 10 months of operation, there have been no failures and no adjustments necessary in any of the seven spark-gap trigger amplifiers used in various spark-chamber experiments at the Lawrence Radiation Laboratory of the University of California (UCLRL) in Berkeley.
Date: October 20, 1964
Creator: Kerns, Q.A. & Miller, H.W.
Partner: UNT Libraries Government Documents Department