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Title: High average power magnetic modulator for metal vapor lasers

Abstract

A three-stage magnetic modulator utilizing magnetic pulse compression designed to provide a 60 kV pulse to a copper vapor laser at a 4.5 kHz repetition rate is disclosed. This modulator operates at 34 kW input power. The circuit includes a step up auto transformer and utilizes a rod and plate stack construction technique to achieve a high packing factor.

Inventors:
 [1];  [2];  [1];  [1]
  1. (Livermore, CA)
  2. (Oakley, CA)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
OSTI Identifier:
869326
Patent Number(s):
US 5315611
Assignee:
United States of America as represented by United States (Washington, DC) LLNL
DOE Contract Number:
W-7405-ENG-48
Resource Type:
Patent
Country of Publication:
United States
Language:
English
Subject:
average; power; magnetic; modulator; metal; vapor; lasers; three-stage; utilizing; pulse; compression; designed; provide; 60; kv; copper; laser; khz; repetition; rate; disclosed; operates; 34; kw; input; circuit; step; auto; transformer; utilizes; rod; plate; stack; construction; technique; achieve; packing; factor; input power; copper vapor; pulse compression; vapor laser; repetition rate; metal vapor; average power; stage magnetic; vapor lasers; magnetic pulse; magnetic modulator; utilizing magnetic; power magnetic; /372/359/

Citation Formats

Ball, Don G., Birx, Daniel L., Cook, Edward G., and Miller, John L. High average power magnetic modulator for metal vapor lasers. United States: N. p., 1994. Web.
Ball, Don G., Birx, Daniel L., Cook, Edward G., & Miller, John L. High average power magnetic modulator for metal vapor lasers. United States.
Ball, Don G., Birx, Daniel L., Cook, Edward G., and Miller, John L. Sat . "High average power magnetic modulator for metal vapor lasers". United States. doi:. https://www.osti.gov/servlets/purl/869326.
@article{osti_869326,
title = {High average power magnetic modulator for metal vapor lasers},
author = {Ball, Don G. and Birx, Daniel L. and Cook, Edward G. and Miller, John L.},
abstractNote = {A three-stage magnetic modulator utilizing magnetic pulse compression designed to provide a 60 kV pulse to a copper vapor laser at a 4.5 kHz repetition rate is disclosed. This modulator operates at 34 kW input power. The circuit includes a step up auto transformer and utilizes a rod and plate stack construction technique to achieve a high packing factor.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sat Jan 01 00:00:00 EST 1994},
month = {Sat Jan 01 00:00:00 EST 1994}
}

Patent:

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  • A three-stage magnetic modulator utilizing magnetic pulse compression designed to provide a 60 kV pulse to a copper vapor laser at a 4.5 kHz repetition rate is disclosed. This modulator operates at 34 kW input power. The circuit includes a step up auto transformer and utilizes a rod and plate stack construction technique to achieve a high packing factor. 19 figs.
  • Magnetic compression circuits show the promise of long life for operation at high average powers and high repetition rates. When the Atomic Vapor Laser Isotope Separation (AVLIS) Program at Lawrence Livermore National Laboratory needed new modulators to drive their higher power copper lasers in the Laser Demonstration Facility (LDF), existing technology using thyratron switched capacitor inversion circuits did not meet the goal for long lifetimes at the required power levels. We have demonstrated that magnetic compression circuits can achieve this goal. Improving thyratron lifetime is achieved by increasing the thyratron conduction time, thereby reducing the effect of cathode depletion. Thismore » paper describes a three stage magnetic modulator designed to provide a 60 kV pulse to a copper laser at a 4. 5 kHz repetition rate. This modulator operates at 34 kW input power and has exhibited MTBF of {approx}1000 hours when using thyratrons and even longer MTBFs with a series of stack of SCRs for the main switch. Within this paper, the electrical and mechanical designs for the magnetic compression circuits are discussed as are the important performance parameters of lifetime and jitter. Ancillary circuits such as the charge circuit and reset circuit are shown. 8 refs., 5 figs., 1 tab.« less
  • A spatial filter includes a first filter element and a second filter element overlapping with the first filter element. The first filter element includes a first pair of cylindrical lenses separated by a first distance. Each of the first pair of cylindrical lenses has a first focal length. The first filter element also includes a first slit filter positioned between the first pair of cylindrical lenses. The second filter element includes a second pair of cylindrical lenses separated by a second distance. Each of the second pair of cylindrical lenses has a second focal length. The second filter element alsomore » includes a second slit filter positioned between the second pair of cylindrical lenses.« less
  • Resonance-transition alkali-vapor lasers have only recently been demonstrated [1] but are already attracting considerable attention. Alkali-atom-vapor gain media are among the simplest possible systems known, so there is much laboratory data upon which to base performance predictions. Therefore, accurate modeling is possible, as shown by the zero- free-parameter fits [2] to experimental data on alkali-vapor lasers pumped with Ti:sapphire lasers. The practical advantages of two of the alkali systems--Rb and Cs--are enormous, since they are amenable to diode-pumping [3,4]. Even without circulating the gas mixture, these lasers can have adequate cooling built-in owing to the presence of He in theirmore » vapor cells. The high predicted (up to 70%) optical-to-optical efficiency of the alkali laser, the superb (potentially 70% or better) wall-plug efficiency of the diode pumps, and the ability to exhaust heat at high temperature (100 C) combine to give a power-scalable architecture that is lightweight. A recent design exercise [5] at LLNL estimated that the system ''weight-to-power ratio'' figure of merit could be on the order of 7 kg/kW, an unprecedented value for a laser of the 100 kW class. Beam quality is expected to be excellent, owing to the small dn/dT value of the gain medium. There is obviously a long way to go, to get from a small laser pumped with a Ti:sapphire or injection-seeded diode system (of near-perfect beam quality, and narrow linewidth) [1, 4] to a large system pumped with broadband, multimode diode- laser arrays. We have a vision for this technology-development program, and have already built diode-array-pumped Rb lasers at the 1 Watt level. A setup for demonstrating Diode-array-Pumped Alkali vapor Lasers (DPALs) is shown in Figure 1. In general, use of a highly-multimode, broadband pump source renders diode-array-based experiments much more difficult than the previous ones done with Ti:sapphire pumping. High-NA optics, short focal distances, and short vapor cells are needed.« less
  • High-average-power ultraviolet (UV) radiation has a wide range of applications of interest to the ISAM program. In the electronics industry, some potential applications are deep-UV photolithography and multichip module production. A variety of polymer processing applications using UV are also under development. New isotope separation missions, such as formaldehyde photodissociation to produce carbon and oxygen isotopes for the medical industry, will require high-power, tunable UV radiation. The practical realization of these applications requires a reliable, cost-effective source of UV. The ISAM program has achieved significant progress towards this goal, demonstrating 9.0 W. at 255.3 nm by frequency doubling the greenmore » (510.6-nm) line of a copper vapor laser. This is believed to be the highest average power ever reported for harmonic generation in the UV. Frequency-doubled copper lasers will be directly applicable to some of the missions mentioned above, but the methods used here are generally applicable to high-average-power UV second-harmonic generation for a variety of sources, including solid-state lasers and dye lasers.« less