Development of a high average current rf linac thermionic injector

Abstract

Thermionic electron guns are capable of operating at high average currents in a variety of vacuum electronic applications, including conventional microwave tubes, but have been replaced by laser photocathode injectors for most applications requiring high-brightness electron beams. However, while laser photocathode guns are capable of providing the very high-brightness beams, they provide an increased level of system complexity and do not extrapolate well to injectors for high average current applications requiring high beam quality. We are developing a 714 MHz injector based on a gridded thermionic electron gun for these applications. This paper presents an experimental study, computer simulations, and analysis of the performance of an existing gridded thermionic electron gun as an injector prototype, and a design concept for an improved injector configuration based on these results.

Asymmetric dual axis energy recovery linac for ultrahigh flux sources of coherent x-ray and THz radiation: Investigations towards its ultimate performance

“…Both these technologies have improved dramatically in the last twenty years and such linac drivers capable of generating femtosecond pulses can be routinely bought from specialised companies. To generate a high-power, high brilliance beam either in THz or X-ray ranges, a high charge electron beam is required and new developments are now bringing Ampere class injectors to reality [2]. The increase of the bunch charge will lead to an increase of photon yield and brilliance during either x-ray Compton scattering [3] or generation of THz radiation [4].…”

Electron Injector Based on Thermionic RF-Modulated Electron Gun for Particle Accelerator Applications

“…The RF gun in Fig. 1(a) is placed at the entrance of the RF acceleration cells, and the electron beam will be directly accelerated by the electric field in the cells [3,11,13,14]. It has the advantage that the cathode structure is simple.…”

“…Liang Zhang, Senior Member, IEEE, Georgia Adam, Boris Militsyn, Wenlong He and Adrian W. Cross beam and has attracted a great deal of interest as an electron beam source in RF linacs [11][12][13][14] as the electron micro-pulses can be matched with the acceleration RF buckets as well as achieving control of the emitted electron beam. The charge, length and emittance of the generated electron bunch are important parameters for the thermionic RF modulated gun used in linacs.…”

Design of a cw, low-energy, high-power superconducting linac for environmental applications

“…The current was limited by very short pulse durations, which is not a requirement of this injector. A prototype gridded thermionic gun at the Naval Research Laboratory delivered a peak current of ~2.2 A at 714 MHz and -24 kV cathode voltage [8,9]. A 300 kV thermionic gun rf-gated at 650 MHz was also recently tested at TRIUMF up to an average current of 10 mA [10].…”