High-current Electron Accelerator Research Articles

Additional radiation factors in high-current electron accelerators

The direct discharge of a pulsed high-voltage generator into a vacuum diode is preferably used in high-current electron accelerators of the first generation. One of the accelerators of this type is the MIG-5000 [i], which at a distance of one meter from the target renders a bremsstrahlung dose race of up to 0.28,10 s C/(kg~sec) at a pulse duration T i = 10 -6 sec and a current of about i0 ~ A. The pulsed operation of the vacuum diode and its mounting behind a radiation-protection shield reduce the radiation in industrial installations co the admissible levels. Only the activity induced by ~--n reactions was considered as an additional source of radiation hazard. However, since the quantum energy is low (Em ax = 2~5 MeV), this factor can be disregarded.

Collective acceleration of ions in a system with an insulated anode

An investigation was made of the processes of collective acceleration of protons in vacuum in a system with an insulated anode and trans-anode electrodes, which were insulated or grounded, in high-current Tonus and Vera electron accelerators. The influence of external conditions and parameters of the electron beam on the efficiency of acceleration processes was investigated. Experiments were carried out in which protons were accelerated in a system with trans-anode electrodes. A study was made of the influence of a charge prepulse and of the number of trans-anode electrodes on the energy of the accelerated electrons. A system with a single anode produced Np=1014 protons of 2Ee < Ep < 3Ee energy. Suppression of a charge prepulse increased the proton energy to (6–8)Ee and the yield was then 1013. The maximum proton energy of 14Ee was obtained in a system with three trans-anode electrodes. A possible mechanism of proton acceleration was analyzed. The results obtained were compared with those of other investigations. Ways of increasing the efficiency of this acceleration method were considered.

Transfer of energy from charged transmission lines with applications to pulsed high-current accelerators

An analysis has been performed of charged transmission-line configurations for use in high-current electron accelerators. Conditions for maximum efficiency and maximum energy transfer to the beam load are derived for ideal constant-impedance lines. It is shown that, in the lossless-line approximation, asymmetric line-pair configurations exist with which both a high accelerating voltage and nominal 100% efficiency can be achieved. The configurations would also have application as a pulse-forming network for use with other switched loads.

The high-current electron accelerator Impul's

The high-current electron accelerator Impul's

High-current accelerator observation of γ+γ→e±

A Monte Carlo calculation is presented for the expected number of γ+γ → e+- events for three geometries of the colliding beams, which are provided by a high-current electron accelerator having a beam current of 50 kA at 1 MeV. The scope for observing such events with the Tonus accelerator is considered on the basis of the background conditions. A scheme for the experiment is presented.

High current electron accelerator in the microsecond range

High current electron accelerator in the microsecond range

Explosive emission of electrons

A review of papers devoted to study and use of the emission of electrons from a metal in contact with plasma clusters formed on explosion of micropoints on a cathode under the influence of thermionic field emission current of high density. A systematic discussion is given of questions of thermionic field emission of electrons from the metal, energy dissipation in cathode micropoints, explosive evaporation of the points, and formation of localized plasmas–cathode flares, which stimulate a rapid increase in electron emission from the cathode. A discussion is given of questions associated with study of the removal of cathode material in the operation of cathode flares and also with the investigation of the parameters of the plasma and the kinetics of its dispersion. The laws governing the removal of electrons from the cathode flare plasma are discussed, as well as the mechanism of electron emission from the metal to the cathode flare plasma. A separate section is devoted to the use of explosive emission in high-current electron accelerators and pulsed x-ray sources. The role of this phenomenon in initiation of electrical discharges in vacuum and gas is also discussed.

Tailoring the accelerating-voltage pulse in a high-current pulsed electron accelerator

Tailoring the accelerating-voltage pulse in a high-current pulsed electron accelerator

Plasma-induced field emission and the characteristics of high-current relativistic electron flow

The results of a comprehensive diode study conducted using a pulsed high-current electron accelerator are reported. Time-dependent analysis of right-cylindrical graphite cathodes has shown evidence of the field emission character of the cold-cathode diode. The effects of cathode whiskers or microprojections on the diode response have been observed. Within a few nanoseconds after the voltage is applied to the diode, the whiskers explode to form cathode flares. The observed diode perveance throughout the remainder of the pulse can be explained in terms of the expansion of the plasma cathode formed by the merger of many cathode flares. Cathode plasma velocities ranged from approximately 2 to 3 cm/μsec. The observed diode behavior was consistent with that predicted by previous studies of high-voltage vacuum breakdown.

In-Vacuum Foil Changer for Intense Relativistic Electron Beam Generators

A device was built permitting in situ changes of the anode foil of high current electron accelerators and thus allowing sizable pulse rate increases of these accelerators.

984. High-current pulsed electron accelerator: S P Bugaev et al, Prib Tekh Eksper, No 6, Nov–Dec 1970, 15–17 ( in Russian)

984. High-current pulsed electron accelerator: S P Bugaev et al, Prib Tekh Eksper, No 6, Nov–Dec 1970, 15–17 ( in Russian)

High-current resonator-type electron accelerator

High-current resonator-type electron accelerator

Space charge effects in high current linear electron accelerator injection systems

Space charge effects in high current linear electron accelerator injection systems

Computer Program for a High-Current Electron Accelerator

A comprehensive computer program for a high-current accelerator operating in the 100 ampere/ 10 MeV range has been developed. The accelerator is a narrow-bandwidth, coupled-cavity device with or without feedback between input and output cavities. Equations for the transient behavior of both the pumped or buildup pnase and the accelerator phase have been programmed to allow for a wide range of design parameters such as number of cavities, cavity-cavity coupling, beam-cavity coupling, cavity loss or Q, stagger tuned cavities, input-output cavity coupling, and injected current as a function of timne. The sinusoidal electric field in each cavity is expanded with the resonant modes, excited by the beam and boundary-matching magnetic current on the center holes. The irrotational field is computed as the unretarded Coulomb field of the beam as a collection of discs and their images. Feedback and feedforward waves in a waveguide which couples input and output cavities are represented by cutoff and propagating waveguide modes decomposed into Fourier components. Some computational properties of the program are discussed.

A high-current electron accelerator

An electron linear accelerator capable of providing high pulsed currents of accelerated electrons is described. The accelerator consists of two coupled resonators excited at a frequency of 137.4 Mc/s by 12 auto-generators each delivering up to 100 kW of power in a 400 μsec pulse. Results obtained with this accelerator are in accordance with the theoretical calculations(1). An electron current of 8.5 A was obtained in a pulse of 0.2 μsec duration and at an energy of 4.5 MeV. The maximum charge of the accelerated electrons per pulse was 3 × 10-6 C.

Use of Oxide-Coated Cathodes in High Current Electron Accelerators

An investigation has been made of the possibility of using an oxide-coated cathode as an electron source for the M.I.T. 320-Mev electron synchrotron. A button cathode originally designed by Sperry Gyroscope Company was redesigned slightly to meet our specifications. With this new cathode, we have obtained an average lifetime of 330 hrs, operated at peak-pulsed current of 200 ma in vacuums as poor as about 10−5 mm Hg. This represents a factor of about 20 improvement in lifetime-current product over directly heated cathodes.