Experimental investigation of a pseudospark-produced high-brightness electron beam

Abstract

A high-brightness electron beam produced by a six-gap pseudospark chamber operated in 5–25 kV voltage and 30–70 mTorr pressure ranges is experimentally investigated. The electron beam of current 150 A at an average energy of 20 keV and pulse duration of 10 nsec is extracted with a repetitive frequency of ∼10 Hz. The electron-beam current scales linearly with the breakdown voltage and about 20% of the stored energy is converted into the total beam energy. The time-integrated rms emittance of the electron beam is measured, and a typical value is found to be 65 mm mrad, yielding a normalized brightness of the beam Bn≊2×1010 A/(m2 rad2).

Pulsed electron beam generation in a simple discharge device

“…The solid line, V b = 25.6/ p 0.256 , where V b is measured in kV and p in mTorr, represents approximately the data points. It is noted that the breakdown voltage characteristic of this particular device is distinctively different from that of pseudospark, 13 which is represented by V b = k / p. 4 As the spark-gap triggers (at t =0) the cathode voltage rises to the full capacitor voltage and collapses after a certain period of delay time t f as shown in Fig. 3.…”

“…Since the discovery of the transient hollow cathode discharge (THCD) such as pseudospark 1 and channelspark, 2 intense pulsed electron beam generation [3][4][5][6] in these spark-like discharges has attracted considerable attention due to its potential applications. Recently, the electron beam produced in channelspark has been successfully utilized for pulsed electron deposition of thin films [7][8][9] as an alternative energy beam to the optical beam in the pulsed laser deposition.…”

“…Such a phenomenon of exponential decay with a relatively long time constant L / R, where L is the inductance of the drift tube and R is the resistance of plasma column, is commonly observed when one attempts to measure electron beam current that propagated through plasma or gas filled drift space as in the case of pseudospark produced electron beam measurement. 4 Other possible phenomena that may affect the Faraday cup signal include the secondary electron emission from the collector and repulsion of low energy electrons by the self biased collector. It is difficult to quantify the effects.…”

Pseudospark-sourced Electron Beam for Millimeter Wave and Terahertz Radiation Generation

“…A pseudospark is an axially symmetric, self-sustained, transient, low pressure (typically 50-500 mTorr) gas discharge in a hollow cathode / planar anode configuration which operates on the low pressure side of the hollow-cathode analogy to the Paschen curve. A potentially useful property of this type of discharge is the formation of an electron beam during the breakdown process [7,8]. During a pseudospark discharge, low temperature plasma is formed as a copious source of electrons and ions and can be regarded as a low work function surface that facilitates electron or ion extraction by applying voltages of different polarity.…”

X-ray emission as a diagnostic from pseudospark-sourced electron beams

“…Such beams possess high current density of up to 10 4 Acm -2 , high brightness up to 10 12 Am -2 rad -2 [4] and require no guiding magnetic field. This is due to the presence of an ion channel which is formed with the generation of the electron beam [5,6,7,8,9].…”