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

Volume

2

fYear

2003

fDate

12-16 May 2003

Firstpage

1309

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 E_acc = 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. E_acc 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;

fLanguage

English

Publisher

ieee

Conference_Titel

Particle Accelerator Conference, 2003. PAC 2003. Proceedings of the

ISSN

1063-3928

Print_ISBN

0-7803-7738-9

Type

conf

DOI

10.1109/PAC.2003.1289688

Filename

1289688