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Measurements of the High Field Q-Drop in TE(sub 011)/TM(sub 010) Mode in a Single Cell Cavity.

DE2005834957

Publication Date	2005
Personal Author	Ciovati, G.; Kneisel, P.
Page Count	14
Abstract	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.
Keywords	Particle accelerators Niobium Quality factors Superconductivity Radio-frequency cavities Performance Superconducting cavity resonators Q-drop Cavity treatments
Source Agency	Technical Information Center Oak Ridge Tennessee
Corporate Authors	Thomas Jefferson National Accelerator Facility, Newport News, VA.; Old Dominion Univ., Norfolk, VA. Dept. of Physics.; Department of Energy, Washington, DC.
Supplemental Notes	Prepared in cooperation with Old Dominion Univ., Norfolk, VA. Dept. of Physics. Sponsored by Department of Energy, Washington, DC.
Document Type	Technical Report
NTIS Issue Number	200521

Measurements of the High Field Q-Drop in TE(sub 011)/TM(sub 010) Mode in a Single Cell Cavity.

Measurements of the High Field Q-Drop in TE(sub 011)/TM(sub 010) Mode in a Single Cell Cavity.
DE2005834957

Publication Date	2005
Personal Author	Ciovati, G.; Kneisel, P.
Page Count	14
Abstract	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.
Keywords	Particle accelerators Niobium Quality factors Superconductivity Radio-frequency cavities Performance Superconducting cavity resonators Q-drop Cavity treatments
Source Agency	Technical Information Center Oak Ridge Tennessee
Corporate Authors	Thomas Jefferson National Accelerator Facility, Newport News, VA.; Old Dominion Univ., Norfolk, VA. Dept. of Physics.; Department of Energy, Washington, DC.
Supplemental Notes	Prepared in cooperation with Old Dominion Univ., Norfolk, VA. Dept. of Physics. Sponsored by Department of Energy, Washington, DC.
Document Type	Technical Report
NTIS Issue Number	200521