Measurements of the high field Q-drop in TE011/TM010 mode in a single cell cavity

Conference · Wed Sep 01 04:00:00 EDT 2004

OSTI ID:834957

Ciovati, Gianluigi; Kneisel, Peter

In the last few years superconducting radio-frequency cavities made of high purity (RRR>200) niobium achieved accelerating gradients close to the theoretical limits. An obstacle towards reproducibly achieve higher fields is represented by some ''anomalous'' losses causing a sharp degradation of the cavity quality factor when the peak surface magnetic field is above about 90 mT, in the absence of field emission. This effect, called ''Q-drop'' has been measured in many laboratories on single- and multi-cell cavities mainly in the gigahertz range. In order to gain some understanding of the nature of these losses, a CEBAF single cell cavity has been tested in the TM010 and TE011 modes at 2 K. The feature of the TE011 mode is to have zero electric field on the cavity surface, allowing to exclude any electric field effect on the Q-drop. This paper will present some of the experimental results for different cavity treatments and will compare them with existing models for the Q-drop.

• Research Organization: Thomas Jefferson National Accelerator Facility, Newport News, VA (US)
• Sponsoring Organization: USDOE Office of Energy Research (ER) (US)
• DOE Contract Number: AC05-84ER40150
• OSTI ID: 834957
• Report Number(s): JLAB-ACC-04-304; DOE/ER/40150-3021
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
NIOBIUM
PERFORMANCE
QUALITY FACTOR
SUPERCONDUCTING CAVITY RESONATORS
SUPERCONDUCTIVITY