Title :
First rf test at 4.2 K of a 200 MHz superconducting Nb-Cu cavity
Author :
Geng, R.L. ; Barnes, P. ; Hartill, D. ; Padamsee, H. ; Sears, J. ; Calatroni, S. ; Chiaveri, E. ; Losito, R. ; Preis, H.
Author_Institution :
Cornell Univ., Ithaca, NY, USA
Abstract :
A 200 MHz single cell elliptical Nb-Cu cavity has been fabricated and tested at 4.2 K and at 2.5 K in a vertical de-war fitted in a radiation shielded pit, 5 m deep and 2.5 m in diameter. The low field Q0 reached 1.5 × 1010 at 4.2 K. Two multipacting barriers show up at Eacc = 3 MV/m and 1 MV/m. Helium processing is effective to reduce field emission and improve accelerating gradients by a factor of as much as 2. Eacc reached 11 MV/m at a Q0 of 6 × 108. The Q-drop is observed but shows a stronger field dependence as compared to expected Q-slope typical for Nb-Cu cavities.
Keywords :
accelerator RF systems; accelerator cavities; beam handling techniques; particle beam dynamics; superconducting cavity resonators; 2.5 K; 2.5 m; 200 MHz; 4.2 K; 5 m; Q-drop; Q-slope; accelerating gradients; field emission; first rf test; helium processing; multipacting barriers; radiation shielded pit; single cell elliptical Nb-Cu cavity; superconducting Nb-Cu cavity; Acceleration; Copper; Niobium; Prototypes; Radio frequency; Shape; Sputtering; Superconducting films; Testing; Welding;
Conference_Titel :
Particle Accelerator Conference, 2003. PAC 2003. Proceedings of the
Print_ISBN :
0-7803-7738-9
DOI :
10.1109/PAC.2003.1289688
