rf breakdown tests of mm-wave metallic accelerating structures
rf breakdown tests of mm-wave metallic accelerating structures
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毫米波金属加速结构的射频击穿测试
DOI：
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发表时间：
2016
期刊：
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通讯作者：
Sami G. Tantawi
中科院分区：
文献类型：
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作者：
M. Forno;V. Dolgashev;G. Bowden;C. Clarke;M. Hogan;D. McCormick;A. Novokhatski;B. Spataro;S. Weathersby;Sami G. Tantawi
我们正在探索亚太赫兹频率下真空射频击穿的物理和频率标度。给出了在金属毫米波加速结构中进行射频测试的实验结果。这些实验是在SLAC国家加速器实验室高级加速器实验测试(FEET)设施中进行的。射频场由小面超相对论电子束激发。我们比较了铜和不锈钢金属结构的性能。基本加速模式的射频频率从115 GHz到140 GHz不等，以光速在结构中传播。行波结构长0.1m，每个行波结构由125个耦合腔组成。我们确定了不受射频击穿破坏的结构的峰值电场和脉冲长度。利用小面束参数计算了与射频击穿相关的电场和磁场。尾迹场由周期本征解的频域方法计算。这种方法考虑了壁面损失，适用于多种几何形状。获得的最大加速梯度为0.3 GV=m，峰值表面电场为1.5 GV=m，脉冲长度约为2.4 ns。
We are exploring the physics and frequency-scaling of vacuum rf breakdowns at sub-THz frequencies. We present the experimental results of rf tests performed in metallic mm-wave accelerating structures. These experiments were carried out at the facility for advanced accelerator experimental tests (FACET) at the SLAC National Accelerator Laboratory. The rf fields were excited by the FACET ultrarelativistic electron beam. We compared the performances of metal structures made with copper and stainless steel. The rf frequency of the fundamental accelerating mode, propagating in the structures at the speed of light, varies from 115 to 140 GHz. The traveling wave structures are 0.1 m long and composed of 125 coupled cavities each. We determined the peak electric field and pulse length where the structures were not damaged by rf breakdowns. We calculated the electric and magnetic field correlated with the rf breakdowns using the FACET bunch parameters. The wakefields were calculated by a frequency domain method using periodic eigensolutions. Such a method takes into account wall losses and is applicable to a large variety of geometries. The maximum achieved accelerating gradient is 0.3 GV=m with a peak surface electric field of 1.5 GV=m and a pulse length of about 2.4 ns.