Abstract
We present a feasibility study for an experiment aiming to post-accelerate an electron bunch, coming from the PHIL (Photo-Injecteur au LAL) photoinjector at LAL (Laboratoire de l’Accélérateur Linéaire), in a circular partially dielectric-loaded waveguide (DLW) driven by a multicycle THz pulse generated by the infrared laser coming from the LASERIX (Installation laser XUV/IR de l’Université Paris Sud) facility. We first discuss the considerations taken into account to fix the DLW design and the THz pulse properties, especially the choice of a 160 GHz THz pulse frequency, and then provide a set of values for their main parameters. We then perform start-to-end simulations of the acceleration experiment, taking into account the current achievable range of parameters at PHIL and the THz pulse properties already achieved with LASERIX with some margins for the coupling losses. They demonstrate the possibility to obtain a 1.2 MeV energy gain for a 10 pC bunch, without charge losses, with a clear shift of the energy spectrum, which would represent a significant improvement compared to the current state-of-the-art of THz acceleration. An overview of the upcoming steps towards the realization of the experiment is finally given.
Highlights
IntroductionParticle acceleration beyond the few-MeV level and their compression down to the single femtosecond order or below currently requires large infrastructures, due to the low frequencies (a few GHz) and relatively low field amplitudes (a few tens of MV/m in the meter-long structures) used in conventional L and S-band accelerating structures
Particle acceleration beyond the few-MeV level and their compression down to the single femtosecond order or below currently requires large infrastructures, due to the low frequencies and relatively low field amplitudes used in conventional L and S-band accelerating structures.One of the schemes currently investigated to reduce the footprint of particle accelerators by several orders of magnitude is to use dielectric-loaded circular waveguides (DLW) driven by multicycle THz pulses [1,2,3,4,5,6], for which the operating frequency (100 GHz to a few THz) and field amplitude are expected to be much higher.A demonstration experiment of this acceleration scheme is currently investigated by the authors
We present a feasibility study for an experiment aiming to post-accelerate an electron bunch, coming from the PHIL (Photo-Injecteur au LAL) photoinjector at LAL (Laboratoire de l’Accélérateur Linéaire), in a circular partially dielectric-loaded waveguide (DLW) driven by a multicycle THz pulse generated by the infrared laser coming from the LASERIX (Installation laser XUV/IR de l’Université Paris Sud) facility
Summary
Particle acceleration beyond the few-MeV level and their compression down to the single femtosecond order or below currently requires large infrastructures, due to the low frequencies (a few GHz) and relatively low field amplitudes (a few tens of MV/m in the meter-long structures) used in conventional L and S-band accelerating structures. One of the schemes currently investigated to reduce the footprint of particle accelerators by several orders of magnitude is to use dielectric-loaded circular waveguides (DLW) driven by multicycle THz pulses [1,2,3,4,5,6], for which the operating frequency (100 GHz to a few THz) and field amplitude (up to a few GV/m) are expected to be much higher. A demonstration experiment of this acceleration scheme is currently investigated by the authors. The basic experimental principle would be to inject the 3-4 MeV electron beam from the S-band gun of the PHIL (Photo-Injecteur au LAL) injector [7] into a DLW driven by a multicycle THz pulse coupled to the TM01 mode (accelerating mode).
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