SRF2013 - List of Keywords (scattering)

Paper	Title	Other Keywords	Page
TUP052	Study on Vertical Electro-Polishing by Cathode With Variable-Geometry Wings	cavity, experiment, cathode, niobium	530
	Y.I. Ida, K.N. Nii MGH, Hyogo-ken, Japan H. Hayano, S. Kato, H. Monjushiro, T. Saeki, M. Sawabe KEK, Ibaraki, Japan K. Ishimi, Y.B. Iwabuchi MGI, Chiba, Japan
	We have been studying on Vertical Electro-Polishing (VEP) of Nb superconducting accelerator cavity for about one year with a view to the mass-production and cost-reduction of Electro-Polishing (EP) process. Marui Galvanizing Co. Ltd. has been in the EP business of various metals for long time and we have matured experience on EP processes. With being based on the experience, we thought that uniform electric-current on the surface of cavity and effective flow of electrolyte in the cavity are important factors. Moreover, we thought the most important effect is given if the cathode and the cavity surface (anode) are kept in a constant distance. Following these considerations, we invented VEP process by a cathode with variable-geometry wings. Using this cathode, we performed several experiments of VEP Nb single-cell cavities as well as fluid circulation test by plastic 9-cell mock-up. In this article, we will report this unique VEP process, which might be applicable to the mass-production process of International Linear Collider (ILC).

TUP106	Second-Sound Measurements on a 3 GHz SRF Cavity at Low Acceleration Fields*	cavity, electron, operation, acceleration	728
	S.T. Sievers, U. Bonnes, C. Burandt, F. Hug, T. Kürzeder, N. Pietralla, A. Richter TU Darmstadt, Darmstadt, Germany
	Funding: *This work is supported by the DFG through the Collaborative Research Center SFB 634. The superconducting Darmstadt electron linear accelerator S-DALINAC uses 20-cell niobium cavities that are operated at a microwave frequency of 3 GHz in liquid helium at a temperature of 2 K. This operation temperature is well below TC = 9.25 K of niobium and guarantees superconducting condition in routine operation. Occasional surface impurities, in particular after venting the beamline following maintenance work, can lead to local quenches which destroy superconductivity of the cavity. In such events it is desirable to have a method for locating and eliminating these surface impurities. In order to locate quench sites in the superconducting cavities during operation in liquid helium a set-up of oscillating superleak transducers (OSTs) was tested in a vertical bath cryostat on a cavity known to quench at very small accelerating fields. Despite the low rf power of approximately 4 W needed to quench the cavity, we were able to identify the quench sites with the OST set-up. Subsequent optical inspection clearly showed surface damages at the determined positions. We will report on our set-up and the procedure.

Paper

Title

Other Keywords

Page

TUP052

Study on Vertical Electro-Polishing by Cathode With Variable-Geometry Wings

cavity, experiment, cathode, niobium

530

Y.I. Ida, K.N. Nii
MGH, Hyogo-ken, Japan
H. Hayano, S. Kato, H. Monjushiro, T. Saeki, M. Sawabe
KEK, Ibaraki, Japan
K. Ishimi, Y.B. Iwabuchi
MGI, Chiba, Japan

We have been studying on Vertical Electro-Polishing (VEP) of Nb superconducting accelerator cavity for about one year with a view to the mass-production and cost-reduction of Electro-Polishing (EP) process. Marui Galvanizing Co. Ltd. has been in the EP business of various metals for long time and we have matured experience on EP processes. With being based on the experience, we thought that uniform electric-current on the surface of cavity and effective flow of electrolyte in the cavity are important factors. Moreover, we thought the most important effect is given if the cathode and the cavity surface (anode) are kept in a constant distance. Following these considerations, we invented VEP process by a cathode with variable-geometry wings. Using this cathode, we performed several experiments of VEP Nb single-cell cavities as well as fluid circulation test by plastic 9-cell mock-up. In this article, we will report this unique VEP process, which might be applicable to the mass-production process of International Linear Collider (ILC).

TUP106

Second-Sound Measurements on a 3 GHz SRF Cavity at Low Acceleration Fields*

cavity, electron, operation, acceleration

728

S.T. Sievers, U. Bonnes, C. Burandt, F. Hug, T. Kürzeder, N. Pietralla, A. Richter
TU Darmstadt, Darmstadt, Germany

Funding: *This work is supported by the DFG through the Collaborative Research Center SFB 634.
The superconducting Darmstadt electron linear accelerator S-DALINAC uses 20-cell niobium cavities that are operated at a microwave frequency of 3 GHz in liquid helium at a temperature of 2 K. This operation temperature is well below TC = 9.25 K of niobium and guarantees superconducting condition in routine operation. Occasional surface impurities, in particular after venting the beamline following maintenance work, can lead to local quenches which destroy superconductivity of the cavity. In such events it is desirable to have a method for locating and eliminating these surface impurities. In order to locate quench sites in the superconducting cavities during operation in liquid helium a set-up of oscillating superleak transducers (OSTs) was tested in a vertical bath cryostat on a cavity known to quench at very small accelerating fields. Despite the low rf power of approximately 4 W needed to quench the cavity, we were able to identify the quench sites with the OST set-up. Subsequent optical inspection clearly showed surface damages at the determined positions. We will report on our set-up and the procedure.