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Development and evaluation of systems for controlling parallel high di/dt thyratrons

Description: Increasing numbers of high power, high repetition rate applications dictate the use or thyratrons in multiple of hard parallel configurations to achieve the required rate of current rise, di/dt. This in turn demands the development of systems to control parallel thyratron commutation with nanosecond accuracy. Such systems must be capable of real-time, fully-automated control in multi-kilohertz applications while still remaining cost effective. This paper describes the evolution of such a control methodology and system.
Date: January 1, 1982
Creator: A., Litton. & McDuff, G.
Partner: UNT Libraries Government Documents Department

Evaluation of bidirectionally conducting thyratrons for pulsed excimer lasers

Description: In the last few years many new applications have been found for excimer lasers in industry and defense programs. Many of these programs have very stringent requirements of lifetime, reliability, and power that are not available commercially. Power conditioning systems capable of driving excimers with reliable lifetimes of 5 billion pulses have been built with off-the-shelf components. In this paper we will discuss the requirements and life test performance of three types of thyratrons designed specifically for driving excimer lasers and also the life of associated components.
Date: January 1, 1984
Creator: McDuff, G.; Rust, K.; Menown, H. & Neale, C.
Partner: UNT Libraries Government Documents Department

Additive enhancement of short pulse flashlamps

Description: A key factor in the development of iodine photodisassociation lasers is the improvement of pump lamp efficiency in the 250 to 300 nm pump band at pulsewidths of about 10 ..mu..s. Previous work by Gusinow showed that certain metal additives appeared to enhance pump lamp output in the 250 to 300 nm region by as much as a factor of three. This had been determined by comparing microdensitometer traces of spectrograms of doped and undoped lamps. The principal problems noted with these lamps were a shot-to-shot variability of more than 30% and an effective life of only 20 shots (a result of migration of the dopants from between the electrodes to the colder regions behind the electrodes).
Date: April 1, 1977
Creator: Shaw, J. F.; Maynard, R. & Lovoi, P.
Partner: UNT Libraries Government Documents Department

Pulse-power circuit diagnostics for the Nova laser

Description: The Nova laser will have a large pulse power system for driving laser amplifiers, incorporating approximately 1600 flashlamp circuits. An automated system has been designed for diagnosing the condition of these flashlamp circuits. It records digitized circuit current waveforms and detects current excursions above a given threshold. In addition, it is able to fire flashlamps at a low energy to ascertain the health of the system. Data from this system can be ploted for inspection by the operator, analyzed by the computer system and archived for future reference.
Date: June 7, 1982
Creator: Christie, D.J.; Dallum, G.E.; Gritton, D.G.; Merritt, B.T.; Whitham, K. & Berkbigler, L.W.
Partner: UNT Libraries Government Documents Department

Construction and performance of large flash chambers

Description: The construction and performance of 12' x 12' flash chambers used in a 340 ton neutrino detector under construction at Fermilab is described. The flash chambers supply digital information with a spatial resolution of 0.2'', and are used to finely sample the shower development of the reaction products of neutrino interactions. The flash chambers are easy and inexpensive to build and are electronically read out.
Date: January 1, 1979
Creator: Taylor, F.E.; Bogert, D.; Fisk, R.; Stutte, L.; Walker, J.K.; Wolfson, J. et al.
Partner: UNT Libraries Government Documents Department

Improved 50-kV pulser design

Description: A compact 50 kilovolt pulser has been developed as a gas switch trigger. This unit combines a grounded grid thyratron with a ferrite loaded step-up transformer to provide the required output voltage. A magnetic switch at the output brings the risetime down to the ten nanosecond range. Unit operation is specified into a 25 ohm resistive load. Integral with the pulser package is the necessary low level support electronics to power the thyratron and to provide trigger and diagnostic functions. Package volume is less than .02 m/sup 3/.
Date: May 27, 1982
Creator: Oicles, J.A. & Fulkerson, E.S.
Partner: UNT Libraries Government Documents Department

Glovebox enclosed dc plasma source for the determination of metals in plutonium

Description: The direct current plasma source of a Beckman Spectraspan IIIB emission spectrometer was enclosed in a glovebox at Lawrence Livermore National Laboratory in December 1982. Since that time, the system has been used for the routine determination of alloy and impurity metals in plutonium. This paper presents the systematic steps involved in developing the glovebox and gives information regarding performance of the plasma in the glovebox and the effectiveness of containment of plutonium. 8 refs., 9 figs., 3 tabs.
Date: January 15, 1986
Creator: Morris, W.F.
Partner: UNT Libraries Government Documents Department

Kicker thyratron experience from SLC

Description: The SLAC Linear Collider has five fast kickers for the damping ring injectors, extractors, and the electron extractor for the positron target that use multi-gap Deuterium-filled thyratrons. The thyratrons operate with 30 to 70 kV anode voltages and 1 to 5 kA currents, to deliver pulses to kicker magnets with {approx} 30 ns rise times, up to {approx} 150 ns pulse widths, at 120 Hz. Operating and lifetime experience with several types of thyratrons and support electronics are discussed. Floating driver and power supply electronics were replaced by a ferrite choke isolator to allow grounding of the cathode support electronics with a commensurate increase in operating reliability. The construction of a 100 ns Blumlein enabled detailed measurements of the switching times for all SLC thyratrons under similar conditions. In the final focus area, the kickers dump the SLC beams after the e{sup +} e{sup {minus}} collisions. These thyratrons function with 15 kV anode voltages and up to 2 kA currents to produce 1/2 sine pulses with {approx} 300 ns rise times, {approx} 550 ns FWHM, at 120 Hz. Operating experience with these thyratrons will also be presented. 7 refs., 1 fig., 3 tabs.
Date: May 1, 1991
Creator: Donaldson, A.R.; Cassel, R.L.; Mattison, T.S. (Stanford Linear Accelerator Center, Menlo Park, CA (United States)) & Reginato, L.L. (Lawrence Livermore National Lab., CA (United States))
Partner: UNT Libraries Government Documents Department

A preliminary design of the Los Alamos fast Kicker Magnet Pulser and Power Supply

Description: The technical design of the Kicker Magnet Pulser and Power Supply is based on the switching of a precharged pulse forming network (pfn) into a matched load. Provisions are made through the selection of the main switch tube to accommodate loads that are not matched to the pfn impedance. The paper includes a description of the major components of the power supply and a summary of the performance parameters. 4 figs., 3 tabs.
Date: January 1, 1988
Creator: Winje, R.A.
Partner: UNT Libraries Government Documents Department

Pulsers for the induction linac experiment, MBE-4

Description: The MBE-4 proof-of-principle experiment uses an induction linac to accelerate four Cs+ beams from injection at 200 kV to almost 1MV. When completed in the summer of 1987 it will be 17.2 meters long and have 24 acceleration gaps and 6 diagnostic gaps. Careful tailoring of the accelerating voltage waveforms at each gap is required to accelerate the beam, amplify the current and provide longitudinal focusing. The ideal voltage waveforms required at the first 4 gaps are almost triangular with an amplitude of about 20 kV and an approximate width of 3 ..mu..sec, becoming flatter and shorter with an amplitude of 30 kV at subsequent gaps as the beam current increases and the pulse width narrows. These waveforms (1) are shown in Fig. 1. Pulser voltage waveforms at each gap are adjusted in both amplitude and firing time in conjunction with beam experiments to determine the required voltage waveforms of the subsequent pulsers. Existing cores and previous experience with thyratron pulsers provided the basis for the pulsers for the first half of the machine. During this fabrication period, additional cores and spark gap pulsers capable of generating higher voltages than the thyratron pulsers became available and a combination of both types of pulser will be used to complete the apparatus.
Date: March 1987
Creator: Gough, D.; Brodzik, D.; Faltens, A.; Pike, C. & Stoker, J.
Partner: UNT Libraries Government Documents Department

Test modulator of AGS injection fast kicker

Description: In this paper, a test modulator of the brookhaven AGS injection fast kicker is described. The AGS injection kicker is the complementary system to the AGS Booster extraction fast kicker. During the fourth batch transfer of the proton beam from the booster to AGS, the fall time of the AGS injection kicker has to be very fast (<140 ns), so that it does not appreciably deflect the first batch of injected protons that is circulating in the AGS. A test modulator was built, which consists of a PFN, a tail-biting section, and two thyratron switches. One thyratron switches the current to the load magnet, and another bites down the current at the end of the pulse. The load and circuit stray inductance is about 1.95 {mu}H to 2.15 {mu}H, and the required peak current is about 1000 Amp. The current pulse waveform, tested at half current level (500 amp), has a fast fall time as well as a fast rise time. The test results will be presented, and some technical difficulties will be discussed. 5 refs., 2 figs.
Date: January 1, 1990
Creator: Zhang, W.; Frey, W.W.; Soukas, A.V.; Zhang, S.Y. & Bunicci, J.
Partner: UNT Libraries Government Documents Department

Step-by-step approach to convective cooling of laser disc amplifiers

Description: A step by step approach is presented to the problem of gas cooling of laser glass amplifiers. The basic equations are given for glass conduction, thermal stress, gas convection, and heat exchanger and blower design. An example calculation is then carried out for helium gas at one atmosphere with the gas flow in the direction orthogonal to the optical path. It is found that pumping powers and temperatures are acceptable for this case. Results are also presented for helium in the slant direction and for nitrogen in both directions. Included also are the effects on pumping power of gas temperature rise, gas pressure, flashtube rep rate, and flow channel width. It is found that, based on temperature rise and pumping power, nitrogen is as viable a coolant as helium.
Date: April 1, 1979
Creator: Bourque, R.F.
Partner: UNT Libraries Government Documents Department

Specific heat loading in Nd:glass lasers

Description: The specific thermal load parameter, chi, for xenon flashlamp-pumped Nd:glass gain media is written as a function of neodymium concentration, pump pulse duration, and energy extraction efficiency. The currently available data on radiative and nonradiative decay probabilities of several commercial Nd:glasses are used to calculate and graph specific thermal load parameter values. By factoring these results into performance scaling relationships for zig-zag and disk lasers, specific Nd:glasses can be selected for optimized laser performance.
Date: August 7, 1985
Creator: Krupke, W.F.
Partner: UNT Libraries Government Documents Department

Discharge circuits and loads

Description: This will be an overview in which some of the general properties of loads are examined: their interface with the energy storage and switching devices; general problems encountered with different types of loads; how load behavior and fault modes can impact on the design of a power conditioning system (PCS).
Date: October 15, 1980
Creator: Sarjeant, W.J.
Partner: UNT Libraries Government Documents Department

Fast thyratron driver

Description: A fast solid-state pulse generator used as a thyratron grid driver for kicker pulsers, has been developed and built with power MOSFETs and a transmission line transformer. The MOSFET, pulsed on and off by a pair of P-N channel HEXFETs, switches charged capacitors into the transformer connected in parallel on one end and in series on the other end to step up the voltage. The resulting output pulse parameters are 2 kilovolts peak (into 50 Ohms), 13 nanoseconds risetime (10--90%), 250 nanoseconds duration, and less than 50 picoseconds pulse-to-pulse jitter. Various methods are employed to protect the MOSFETs from thyratron arc back, including the use of TransZorbs and a magnetic diode. 3 refs., 3 figs.
Date: April 1, 1991
Creator: Nguyen, M.N. & Cassel, R.L.
Partner: UNT Libraries Government Documents Department

Second generation SLAC modulator

Description: The Stanford Linear Accelerator Laboratory has undertaken the construction of a single pass electron-positron collider. In order to reach required beam energy 235 new klystrons needed upgraded modulator systems. The collider will use 50 GeV electrons and positrons. The increase in accelerator energy from the present 30 GeV necessitates the replacement of existing 35 MW klystrons with new 67 MW units. The doubling of klystron output power required a redesign of the modulator system. The 67 MW klystron needs a 350 kV beam voltage pulse with a 3.7 ..mu..s pulse width. A new pulse transformer was designed to deliver the increased voltage and pulse width. Pulse cable design was evaluated to obtain increased reliability of that critical element. The modulator, with the exception of its power supply, was rebuilt to produce the required power increase while enhancing reliability and improving maintainability. An investigation of present thyratron switch tube performance under the new operating conditions resulted in agitation and some warranted panic but these conditions were mitigated after several successful experiments and some evolutionary narrowing of the klystron pulse width. The discussion will cover the upgraded modulator system specifications and some details of the new pulse transformer tank, pulse cable, modulator, and modulator switch tube.
Date: June 1, 1986
Creator: Donaldson, A.R.; Cron, J.C. & Hanselman, R.R.
Partner: UNT Libraries Government Documents Department

SLC positron source flux concentrator modulator

Description: The modulator for the SLC e+ source flux concentrator provides 16 kA in a 5 {mu}s sinusoidal half wave current for a pure inductive load, at 120 Hz. The modulator incorporates 10 EEV CX1622 thyratrons in a switching network. It provides reliable operation with acceptable thyratron lifetime. 3 refs., 3 figs., 1 tab.
Date: June 1, 1991
Creator: de Lamare, J.; Kulikov, A.; Cassel, R. & Nesterov, V.
Partner: UNT Libraries Government Documents Department

Some fast beam kicker magnet systems at SLAC

Description: The Stanford Linear Collider requires very fast rise and fall times from its kicker magnets. The damping rings and positron source need either one or two bunches deflected from two or three that are separated in time by about 59 ns. The final focus region kicker magnets need a rise time of less than 700 ns and each one deflects only one bunch. This paper discusses the design and characteristics of a thyratron-switched, castor-oil-filled, coaxial, Blumlein line used for one bunch kicking. It discharges a 118 ns (at the base), 50 kV, 3 kA pulse into a 33 cm long, ferrite-loaded, kicker magnet of rectangular coaxial-line geometry, which in turn is terminated by a matched load. Reference is made to a Fermilab (FNAL) designed magnet and a dual-thyratron pulsar that will deflect two serial bunches in or out of the electron ring. Also, a brief description of the final focus magnet is given. Work is continuing on the various subsystem components to decrease the pulse rise and fall time, flattop ripple and jitter and to reduce some of the sources of noise and hv breakdown.
Date: January 1, 1987
Creator: Bulos, F.; Cassel, R.L.; Donaldson, A.R.; Genova, L.F.; Grant, J.A.; Mihalka, A.M. et al.
Partner: UNT Libraries Government Documents Department

Status of the SLC damping ring kicker systems

Description: The damping ring kickers for the SLAC Linear Collider must meet extreme requirements on rise and fall time, flatness, time and amplitude jitter and drift, voltage, repetition rate, and reliability. After several generations of improvements to the pulsers, magnets, and controls, and evolution in the understanding of the requirements, the kicker systems are no longer a serious constraint on SLC performance. Implications for future linear colliders are discussed. 14 refs.
Date: May 1, 1991
Creator: Mattison, T.; Cassel, R.; Donaldson, A.; Gough, D.; Gross, G.; Harvey, A. et al.
Partner: UNT Libraries Government Documents Department

Toroidal helical quartz forming machine

Description: The Scyllac fusion experimental machine used 10 cm diameter smooth bore discharge tubes formed into a simple toroidal shape prior to 1974. At about that time, it was discovered that a discharge tube was required to follow the convoluted shape of the load coil. A machine was designed and built to form a fused quartz tube with a toroidal shape. The machine will accommodate quartz tubes from 5 cm to 20 cm diameter forming it into a 4 m toroidal radius with a 1 to 5 cm helical displacement. The machine will also generate a helical shape on a linear tube. Two sets of tubes with different helical radii and wavelengths have been successfully fabricated. The problems encountered with the design and fabrication of this machine are discussed.
Date: January 1, 1977
Creator: Hanks, K.W. & Cole, T.R.
Partner: UNT Libraries Government Documents Department

Repetitive MEGAMP per microsecond di/dt pulsers for driving sub-ohm transmission line neutrino particle detectors

Description: With the advent of low-cost honeycomb extrusions of polypropylene sheets, transmission line flash chambers have become highly attractive candidates for large particle detector arrays. This has brought about the need for repetitive pulse systems that must provide exceptionally high peak currents, low levels of spurious radiation, high reliability, and shot life in excess of 10/sup 7/. Each module of 10 flash chambers requires a peak current of 20 kA with a current di/dt greater than 1 MA/..mu..s. The pulser output must develop approx. = 7 kV across a load of 0.5 ..cap omega.. with a pulse width of 500 ns. The complete system will require 40 pulsers run in parallel for a combined current output of 1.4 MA peak with a system di/dt of 40 MA/..mu..s. The repetition rate will be up to 2 Hz. This paper describes the development of such a system, its unique voltage and current diagnostics, and the impact of the physical limitations of present component technology on lifetime, reliability, maintainability, and pulse fidelity.
Date: January 1, 1980
Creator: Krausse, G.J.; Dalton, C.G. & Sarjeant, J.
Partner: UNT Libraries Government Documents Department

Design and construction of large capacitor banks

Description: Over the past 12 years, the Laser Program at LLNL has actively pursued laser fusion, using a series of large, solid-state lasers to develop target data leading to reactor designs using the concept of inertial confinement fusion. These lasers are all linear chains of flashlamp driven, Nd-doped glass amplifiers with a master oscillator at the front end. Techniques have been developed during this time to scale the lasers to an arbitrarily large size. A table shows the series of lasers and their parameters that have been developed to date.
Date: January 1, 1983
Creator: Whitham, K.; Gritton, D.G.; Holloway, R.W. & Merritt, B.T.
Partner: UNT Libraries Government Documents Department

Flow visualizations, velocity measurements, and surface convection measurements in simulated 20. 8-cm Nova box amplifier cavities

Description: Reported are fluid mechanics experiments performed in models of the 20.8-cm Nova amplifier lamp and disk cavities. Lamp cavity nitrogen flows are shown, by both flow visualization and velocity measurements, to be acceptably uniform and parallel to the flashlamps. In contrast, the nitrogen flows in the disk cavity are shown to be disordered. Even though disk cavity flows are disordered, the simplest of three proposed nitrogen introduction systems for the disk cavity was found to be acceptable based on convection measurements made at the surfaces of simulated laser disks.
Date: October 31, 1983
Creator: Julien, J.L. & Molishever, E.L.
Partner: UNT Libraries Government Documents Department