[en] This paper reports on large-area electron guns that are critical components in many high-energy gas laser systems. The secondary emission electron (SEE) gun offers an attractive option for pulsed laser applications. With this type of cold cathode gun, a dc voltage is applied to the cathode and the electron beam is generated by secondary emission due to ion bombardment processes. The gun is controlled by modulating the source of ions which resides at ground potential. This design greatly simplifies the electron gun power system. SEE-gun systems have been developed which provide 150-220 keV beams at current densities exceeding 25 mA/cm² with current density uniformities of approximately ±10% over areas of up to 5 x 150 cm². Pulse lengths have ranged from 30 μs to 20 ms at repetition rates from single-pulse to 30 Hz. It is expected that the SEE-gun can be scaled to beam voltages of greater than 300 kV, beam areas greater than 1 m², peak current densities exceeding 1 A/cm², time-averaged current densities approx-gt 0.5 mA/cm², pulse lengths of 0.1 μs to dc, and pulse repetition rates >1 kHz with good uniformity, high reliability and long life. Furthermore, the inherent simplicity of the SEE-gun results in low cost and a compact, light-weight system

[en] The SLAC National Accelerator Laboratory employs 244 klystron modulators on its two-mile-long linear accelerator that has been operational since the early days of the SLAC establishment in the sixties. Each of these original modulators was designed to provide 250 kV, 262 A and 3.5 μS at up to 360 pps using an inductance-capacitance resonant charging system, a modified type-E pulse-forming network (PFN), and a pulse transformer. The modulator internal control comprised of large step-start resistor-contactors, vacuum-tube amplifiers, and 120 Vac relays for logical signals. A major, power-component-only upgrade, which began in 1983 to accommodate the required beam energy of the SLAC Linear Collider (SLC) project, raised the modulator peak output capacity to 360 kV, 420 A and 5.0 μS at a reduced pulse repetition rate of 120 pps. In an effort to improve safety, performance, reliability and maintainability of the modulator, this recent upgrade focuses on the remaining three-phase AC power input and modulator controls. The upgrade includes the utilization of primary SCR phase control rectifiers, integrated fault protection and voltage regulation circuitries, and programmable logic controllers (PLC) -- with an emphasis on component physical layouts for safety and maintainability concerns. In this paper, we will describe the design and implementation of each upgraded component in the modulator control system. We will also report the testing and present status of the modified modulators.

[en] There are many industrial radiation processes that require electron beam sources capable of operating at 1-10 MeV and power levels of 50-500 kW. These processes include medical product sterilization, food sterilization and decontamination of waste products. Linear induction accelerators (LIAs) driven by magnetic pulse compression (MC) systems are particularly attractive for these applications. Pulse Sciences, Inc. has developed a prototype LIA/MC system to demonstrate the capabilities of this technology to meet industrial requirements where low cost, high efficiency and high reliability are essential. The prototype is designed to operate at a beam energy of 1.6 MeV and a beam current of 1-2 kA in 65 ns pulses at average powers exceeding 20 kW. Higher energies and average power levels can be achieved by adding more acceleration modules and by increasing the pulse repetition rate. This paper discusses the prototype system design and its performance characteristics. (orig.)

[en] This letter presents measurements of the specific energy consumption (eV per molecule) for electron-impact dissociation of N₂ (e+N₂→e+N+N) in a pulsed corona and an electron beam reactor. Measurements were done using 100 pm of NO in N₂. In this mixture the removal of NO is dominated by the reduction reaction N+NO→N₂+O. By measuring the specific energy consumption for reduction of NO, these experiments provide a good measure of the specific energy consumption for electron-impact dissociation of N₂. The specific energy consumption using pulsed corona processing is 480 eV per dissociated N₂ molecule. For electron beam processing, the specific energy consumption is 80 eV per dissociated N₂ molecule. copyright 1995 American Institute of Physics

[en] Non-thermal plasma techniques represent a new generation of air emission control technology that potentially could treat large-volume emissions containing dilute concentrations of volatile organic compounds (VOCs). In order to apply non-thermal in an industrial scale, it is important to establish the electrical power requirements and byproducts of the process. There is a need for reliable data concerning the primary decomposition mechanisms and subsequent chemical kinetics associated with non-thermal plasma processing of VOCs. There are many basic atomic and molecular physics issues that are essential in evaluating the economic performance of non-thermal plasma reactor. These studies are important in understanding how the input electrical power is dissipated in the plasma and how efficiency it is converted to the production of the plasma species (radicals, ions or electrons) responsible for the decomposition of the VOCs. This paper presents results from basic experimental and theoretical studied aimed at identifying the reaction mechanisms responsible for the primary decomposition of various types of VOCs. (Authors)