Cryogenic surface resistance of copper: Investigation of the impact of surface treatments for secondary electron yield reduction
Cryogenic surface resistance of copper: Investigation of the impact of surface treatments for secondary electron yield reduction
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DOI：
10.1103/physrevaccelbeams.22.063101
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发表时间：
2019-06-20
影响因子：
1.7
通讯作者：
Abdolvand, Amin
中科院分区：
文献类型：
--
作者：
Calatroni, Sergio;Arzeo, Marco;Abdolvand, Amin
用CERN的四极共振器首次在低温下测量了具有非晶碳（a-C）涂层或具有激光表面结构的铜样品的表面电阻，这些表面处理是大型强子对撞机（HL-LHC）高亮度升级的关键低温部门中电子云抑制的选择。三个不同的频率的相关性评估束阻抗的影响，即，400，800和1200 MHz，进行了研究。与普通铜相比，对于a-C涂层没有观察到表面电阻的显著增加。在激光成型的情况下，表面电阻取决于表面电流相对于激光雕刻凹槽图案的方向。平行图案的增加是最小的，但在垂直的情况下，表面电阻显著增加。在HL-LHC的情况下，来自尾流损失的射频（rf）加热也会增加;然而，由于电子云抑制，沉积在冷表面上的功率减少仍然会超过这种影响。
The surface resistance of copper samples with an amorphous carbon (a-C) coating or with laser surface structuring, the surface treatments of choice for electron cloud suppression in critical cryogenic sectors of the high-luminosity upgrade of the Large Hadron Collider (HL-LHC), has been measured for the first time at a cryogenic temperature using the quadrupole resonator at CERN. Three different frequencies of relevance for evaluating beam impedance effects, namely, 400, 800, and 1200 MHz, have been investigated. No significant increase in surface resistance is observed for the a-C coating, compared to plain copper. In the case of laser structuring, the surface resistance depends on the direction of the surface currents relative to the laser-engraved groove pattern. The increase is minimal for parallel patterns, but in the perpendicular case the surface resistance increases considerably. Radio frequency (rf) heating from wake losses would then also increase in the HL-LHC case; however, the reduction in the power deposited onto the cold surfaces thanks to electron cloud suppression would still outweigh this effect.