The axially modulated, cusp-injected, large-orbit gyrotron amplifier

Abstract

We introduce a novel hybrid microwave amplifier that utilizes the axial bunching mechanism of klystrons in conjunction with the energy extraction mechanism of cyclotron resonance masers. A simple analytic model is used to show the viability of the device configuration and to explore limitations of the scheme. An example of an 11 GHz, 1 MW, fourth harmonic amplifier is presented. Adopting a single-particle approach, numerical simulations are used to demonstrate bunching in physical space and to estimate system efficiency. It is shown that this configuration enables the design of efficient, high harmonic devices over a wide range of parameters.

Design of an efficient, low voltage, third harmonic, large-orbit gyrotron amplifier with a vane-resonator output cavity

“…In this paper we have demonstrated, via a concrete design, the feasibility of the low voltage, high efficiency, pre-bunched, gyrotron concept at the third harmonic. The principle extension of this work beyond our previous study [25] involves the introduction of a vane-resonator output cavity. This configuration allows a reduction in the transverse dimensions of the cavity for a given frequency and azimuthal mode number and results in vastly improved beam coupling to low energy, axisencircling beams.…”

“…A detailed description of the operation of this device was given in [25]. In this section we briefly note the key aspects of the design and simulation processes and detail only the novel aspects of this work, which involve the use of a vane resonator (VR) output cavity.…”

“…The spread in beam energy translates into additional velocity spread after the magnetic transition. When the effects of the input cavity's magnetic fields are neglected, the induced spread can be approximated by [25] In (2), yo is the relativistic mass factor.…”

“…One of these techniques utilizes a modified version of the klystron's ballistic bunching process to generate the required velocity distribution. A device based on this technique, which we call the axially-modulated, cusp-injected, large-orbit gyrotron, has been explored in an earlier paper for a system with a 100 kV, 25 A beam [25].…”