Pseudospark-based electron beam and Cherenkov maser experiments

Abstract

Detailed experimental results from the first free-electron maser experiment to use a pseudospark-based electron beam are presented in this paper. These include the design and realization of a pseudospark-based electron beam source and Cherenkov maser experiment. A pulsed, 70-80 kV, 10 A electron beam was obtained from the hollow cathode discharge phase of an 8-gap pseudospark (PS) discharge. The beam was used to produce coherent microwave radiation via a Cherenkov interaction between the electron beam and the TM01 mode of a 60-cm long alumina-lined waveguide. A gain of 29+/-3 dB was measured and an output power of 2+/-0.2 kW in the frequency range 25.5-28.6 GHz. Results from numerical simulations of the Cherenkov amplification are also presented and found to be consistent with the experimental results

Pseudospark Experiments: Cherenkov Interaction and Electron Beam Post-Acceleration

“…For values of the beam and waveguide parameters relevant to this experiment, the force exerted on the electrons by the waveguide mode was dominated by the resonant space-charge force, so the maser operated in a Raman-type regime, with strongest amplification of the waveguide mode expected when it was resonant with the slow space-charge wave of the beam, i.e., when the angular frequency and the axial wavenumber of the waveguide mode satisfy (1) where is the axial electron velocity, is the relativistic factor, is the plasma frequency, is the electron density, , is the relative velocity, is the total electron velocity, is the speed of light, and and are the electronic charge and rest mass, respectively. and must also, of course, satisfy the characteristic equation for a dielectric-lined cylindrical waveguide, which for a mode is as in [7]. From the space-charge mode of the electron beam and the and waveguide modes for this Cherenkov maser experiment, a resonant interaction of the beam mode would be expected to occur around 21 GHz with the mode and 55 GHz with the mode.…”

“…The main components of the experiment are the PS-based electron beam source, the magnetic field for beam transport, the Cherenkov interaction region, electrical/beam diagnostics, and the microwave launching/diagnostic system. A more detailed description of the experimental setup can be found in [7].…”

“…This beam has a higher combined current density and brightness compared to electron beams formed from any other known type of electron source. A PS-based, high-intensity, high-brightness electron beam source was applied for the first time in a free-electron maser device at the University of Strathclyde [6], [7].…”

Compact millimetre wave and terahertz radiation sources driven by pseudospark-generated electron beam

“…During a PS discharge, low temperature plasma is formed that acts as a copious source of electrons facilitating electron extraction to form electron beam of diameters in the range from millimetre to microns. The propagation property of this PS sourced beam is further investigated experimentally and in simulation, which proved the beam's propagation without external guiding magnetic field and its potential applications in the generation of millimetre wave and sub terahertz radiation [5][6][7][8].…”

Preliminary design of a G-band extended interaction oscillator driven by a sheet electron beam

“…In the millimeter and sub-millimeter wavelength community, RF sources with compact configuration, high efficiency, and high output power have many potential applications, including satellite communications, radars, molecular spectroscopy, bioimaging, and plasma science [1][2][3][4][5][6][7][8][9][10][11]. The extended interaction oscillator (EIO) has been widely studied as a promising source to satisfy some of these applications, due to its high radiation power and compact configuration [1][2].…”