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A thermionic cusp electron gun has been designed, numerically optimized and experimentally measured and is presented. A 40 kV, 1.5 A annular axis-encircling electron beam has been simulated to generate a beam with low velocity and alpha spreads. The electron gun performance has been verified through experiments and the results are given.
Summary form only given: Demands in plasma diagnostics, radiotherapy, medical research and advanced communications have in recent years resulted in the development of new radiation sources in the terahertz region (0.1 to 10 THz). A klystron is one attractive choice for generation of THz radiation due to its operation mechanism, efficiency and robustness and because its structure is amenable to being...
In this paper, we report the observation of high-current (1.5 kA), magnetically confined, annular electron beams with circumference of -220 mm and wall thickness of ~2 mm and its transportation through the 2 m coaxial beam channel with inner/outer radii of 30 mm/40 mm respectively. The results of the experimental studies of a FEM driven by such an electron beam are presented. The results of FEM lasing...
The design, simulation and experiment of a thermionic cusp electron gun that is to be used for millimeter wave generation will be presented. A cusp gun uses a non-adiabatic magnetic field reversal to obtain azimuthal motion on an electron beam resulting in an annular shaped, axis-encircling beam. The cusp gun was designed to generate a beam of 1.5 A at 40 kV with an adjustable velocity ratio of up...
A novel thermionic cusp electron gun operating in the temperature-limited regime that produces a large-orbit electron beam through a nonadiabatic magnetic-field reversal was designed, analyzed, and optimized to give an electron-beam ideal for driving gyro-devices, particularly in the millimeter-to-submillimeter-wavelength range due to its small cross-sectional size. The annular-shaped axis-encircling...
High power millimeter and sub-millimeter wave sources operating in the high GHz - THz (35 GHz-1 THz) frequency range are important for a number of applications. This work will focus on the overview of recent theoretical and experimental research conducted at the University of Strathclyde to design, build and study masers operating at 37.3 GHz, 91.2 GHz and 0.74 THz. The results obtained will be presented...
This paper presents an overview of a coaxial free-electron maser (FEM) based on 2D and 1D distributed feedback, driven by a large diameter (70 mm) annular electron beam. Most recent experimental results and numerical simulations are presented and discussed. Particle in cell (PiC) code MAGIC is used to demonstrate the possibility to control the operating mode and frequency of the output radiation....
The latest results of experimental investigations of an X-band gyro-TWA using a cusp gun and a helically corrugated interaction region are presented. Results will be presented from two experimental investigations, one using a 150 kV, 35 A beam from a cold field emission cusp gun and one with a 150 kV, 70 A beam from a thermionic cusp gun. Designs for a gridded thermionic cusp gun currently under construction...
This paper presents the design of a W-band gyro-BWO with a helically corrugated waveguide and a cusp electron gun. Results are presented of simulations of the cusp gun and microwave measurements of the interaction region using a vector network analyser. Over the frequency range 85-105 GHz the helically corrugated waveguide was found to have an average loss of just under 1 dB. Also, the waveguide dispersion...
Experimental studies of the production and propagation of an electron beam from a multi-gap pseudospark discharge chamber are presented. A beam up to 680 A was measured at the anode when a three-gap pseudospark underwent a breakdown at an applied DC voltage of 23 kV. This beam can propagate further downstream as far as 20 cm in length in a gaseous environment (pressure = 60 mtorr) with no guiding...
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