| Paper | Title | Page |
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| THCAU02 | Development of High-average-current RF Injectors | 511 |
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A key component of the high-average-power free-electron laser is a low emittance, high-average-current RF injector. The RF injector typically consists of a high gradient structure with integer-and-a-half RF cells. The cathode is located on the wall of the first half cell where very high accelerating gradients are applied to quickly accelerate electrons to relativistic velocities. While the average gradient can exceed 100 MV/m in a pulsed normal conducting RF injector, it is only 7 MV/m in a cw normal-conducting RF gun and approximately 25 MV/m in a cw superconducting RF gun. Emittance compensation has been achieved in NCRF injectors with an axial solenoid magnetic field near the photocathode to generate nanocoulomb bunch charge with low rms emittance. The use of emittance compensation eliminates the need for ultrahigh accelerating gradients, and enables the generation of nanocoulomb bunches with normalized rms emittance on the order of a few mm-mrad. This paper reviews the current state-of-the-art of cw, high-average-current RF injectors, using both normal-conducting and superconducting RF accelerator technologies.
D. C. Nguyen et al., Nucl. Instr. Meth. Phys. Res., A 528 (2004) 71-77. |