Development of a high-gradient X-band RF gun with replaceable field emission cathodes for RF breakdown studies

Development of an X-band RF gun with four-feed coupler

“…According to our machining accuracy, it keeps working effectively within the ±0.02 mm offset of the centre of the gap from A1 to A2 shown in Figure 1. And the 2.37cell X-band rf gun with replaceable cathodes has been fabricated and tested on TpoT-X in Tsinghua University [3], further illustrating the feasibility of this replaceable cathode structure. However, the prediction about the long-time exposure of electron gun and cathode to the air during the replacing period is absence in our scheme.…”

“…Since the first cell of the field emission electron gun is thinner than that of the photocathode electron gun, the long-to-short axis ratio of the elliptical arc of the iris of the first cavity is further optimized to 2.5 after parametric scanning in order to reduce the surface electric field intensity on the beam aperture. According to previous calculations, the maximum energy gain of the electron beam will be obtained at the exit when the first cavity length is set to 0.37-cell [3]. We took the 0.5cell singlecavity L-band rf gun in AWA as a precedent and modified our gun from 2.37-cell to 0.37-cell singlecavity structure [8].…”

“…Tsinghua University accelerator laboratory has also con-ducted related experiments on Tsinghua X-band high-power test stand (TpoT-X). Liuyuan Zhou have built an X-band (11.424 GHz) RF gun combining with an imaging beamline to observe the evolution of copper cathode [3,4]. Scheme of the two test stands above is illustrated in Figure 1.…”