Theory of electron-cyclotron-resonance laser accelerators

Abstract

The cyclotron resonance laser (CRL) accelerator is a novel concept of accelerating continuous charged-particle beams to moderately or highly relativistic energies. This paper discusses prospects and limitations of this concept. In particular, the nonlinear coupling of an intense traveling electromagnetic wave with an electron beam in a guide magnetic field is studied, and the effects of wave dispersion on particle acceleration are analyzed. For a tenuous beam, it is shown in a single-particle theory that the maximum energy gain and the maximum acceleration distance for the beam electrons in CRL accelerators with optimal magnetic taper exhibit power-law scaling on the degree of wave dispersion (measured by the parameter w/ckjj -1). The maximum energy gain is found to be independent of the wave amplitude, and the accelerating gradient is proportional to the wave amplitude. A self-consistent multiparticle model, which confirms the validity of the scaling laws, is used to study the characteristics of CRL accelerators in moderately high-current, microwave regimes. The parameter regimes of experimental interest are identified. The possibility of building continuous-wave (CW) CRL accelerators is discussed. Finally, the results of simulation modelling of a multi-megavolt, X-band, electron CRL accelerator are presented.

Particle acceleration by large-amplitude waves revisited

“…With the advent of powerful radiation-generation systems such as free-electron lasers, cyclotron autoresonance masers, gyrotrons and ion-channel lasers, a good deal of effort has been directed to the study of the interaction of low-energy particles and large-amplitude electromagnetic waves (Sprangle et al 1983;Davidson et al 1989;Chen 1992;Pakter et al 1993Pakter et al , 1994aFriedland 1994;Kuo and Lee 1994). Whenever wave-particle exchange is likely to occur, particles can be strongly accelerated, a feature of importance not only for particle acceleration itself, but also for the current-drive techniques of controlled thermonuclear research.…”

Proposed research on advanced accelerator concepts

“…Because the basic equations for the CARM and CRL accelerator are identical, the CSPOT code can also be used for CRL accelerator simulation and design [5], [6]. Unlike a single-particle model, the code take into account the self-consistent interaction between the driving wave and the electron beam, which is important in the high-current regime where the wave amplitude and phase vary substantially in the acceleration process.…”

“…Self-consistent modelling of a 33.3 GHz high-current, high-efficiency CRL accelerator A detailed design modelling of a high-current CRL accelerator has been conducted in the microwave regime [6], using a three-dimensional self-consistent simulation code CSPOT [15], [18]. The code takes into account the self-consistent evolution of the amplitude and phase of the driving wave due to the cyclotron resonance interaction in the high-current regime.…”

“…Investigations of physics issues related to particle acceleration including twobeam accelerators [2]- [4] and cyclotron resonance laser (CRL)accelerators [5], [6].…”

Self-consistent chaos and Arnold diffusion in a cyclotron-maser wave-particle system

“…Chen [6], for instance, uses tapered magnetic Gelds to maintain the resonance that would be otherwise destroyed by dispersion. Alternatively, Pakter et al [7] make use of a small mismatch between the Doppler-shifted cyclotron and wave &equencies to completely compensate the dispersive effects.…”