800MHz Crab Cavity Conceptual Design For the LHC Upgrade

In this paper, we pre­sent a 800MHz crab cav­i­ty con­cep­tu­al de­sign for LHC up­grade, in­clud­ing the cell shape op­ti­miza­tion, and LOM, SOM, HOM and input cou­pler de­sign. The com­pact coax-to-coax cou­pler scheme is pro­posed to cou­ple to the LOM and SOM modes which can pro­vide strong cou­pling to the LOM and SOM modes. HOM cou­pler de­sign uses a two-stub an­ten­na with a notch fil­ter to cou­ple to the HOM modes in the hor­i­zon­tal plane and re­ject the op­er­at­ing mode at 800MHz. All the damp­ing re­sults for the LOM/SOM/HOM modes sat­is­fy their damp­ing re­quire­ments. The mul­ti­pact­ing in cell and cou­plers is sim­u­lat­ed as well. And the issue of the cross-cou­pling be­tween the input cou­pler and LOM/SOM cou­plers due to cav­i­ty asym­me­try is ad­dressed. The power com­ing out of the LOM/SOM/HOM cou­plers are es­ti­mat­ed. All the sim­u­la­tions are car­ried out using SLAC de­vel­oped par­al­lel EM sim­u­la­tion codes Omega3P, S3P and Track­3P.