Test plan of ESS Spoke series CM Han

Test plan of ESS Spoke series CM Han Li On behalf of FREIA team FREIA Laboratory, Uppsala University Oct. 2020 1

List of minimum tests 1 Central cavity frequency To reach 352. 21 MHz Within step tuner linear zone Provide corresponding step tuner setting 2 Loaded Q Both 3 d. B BW and decay measurement, 1. 75 -2. 85 E 5 3 Static heat load 4 Dynamic heat load for both cavities from 8 to 12 MV/m Less than 5 W per CM at nominal Eacc 5 Q 0 Calorimetric measurement Higher than 1. 5 e 9 at 9 MV/m 6 Reach gradient of 12 MV/m Quench point if it is lower than 12 MV/m 7 Tuning sensitivity of the slow step tuner Provide parameter of full steps 8 Frequency shift due to cool down 9 Stabilization of the cavity field with LLRF using both RF and piezo tuner compensation Optional only for 1 st CM full LFD compensation up to the specifications only when piezo feedback is fully developed 10 Stabilization of the CM for long-term operation only for 1 st CM 11 Field emission onset 12 Multipacting 2

Methods for the main test items 1 Central cavity frequency S parameter measurement via vector network analyzer 2 Loaded Q Both 3 d. B BW and decay measurement 3 Static heat load 4 Dynamic heat load for both cavities from 8 to 12 MV/m Calorimetric measurement via the flowmeter placed after the sub-atmospheric pumps 5 Q 0 6 Reach gradient of 12 MV/m 7 Tuning sensitivity of the slow step tuner 8 Frequency shift due to cool down 9 Stabilization of the cavity field with LLRF using both RF and piezo tuner compensation 10 Stabilization of the CM for long-term operation 11 Field emission onset X-ray observation as a function of gradient 12 Multipacting Conditioning with ESS LLRF open loop / auto-conditioning Lab. View program PID/Open loop operation with ESS LLRF system S parameter measurement via vector network analyzer PID operation with ESS LLRF system 3

Warm Test Cool Down ü Central cavity frequency ü Qext ü Frequency shift ü Coupler cold conditioning due to cool down ü Central frequency ü Pressure sensitivity ü Loaded Q and Qe ü Tuning range of the slow step tuner ü Cavity conditioning ü Steady heat load of CM ü Q 0 ü Dynamic heat load ü Reach 9 MV/m ü Stabilization of the cavity field ü Coupler warm conditioning Cold Test Open loop SEL ( back up) VNA ESS LLRF PID Warm Up CRYO 4