SRF2011 - List of Authors (Teichert, J.)

Paper

Title

Page

Modified SRF Photoinjector for the ELBE at HZDR

39

P. Murcek, A. Arnold, H. Büttig, D. Janssen, M. Justus, P. Michel, G.S. Staats, J. Teichert, R. Xiang
HZDR, Dresden, Germany
P. Kneisel
JLAB, Newport News, Virginia, USA

The superconducting radio frequency photoinjector (SRF photoinjector) with Cs2Te cathode has been successfully operated under the collaboration of BESSY, DESY, HZDR, and MBI. In order to improve the gradient of the gun cavity and the beam quality, a new modified SRF gun (SRF-gun2008) has been designed. The main updates of the new cavity design for the new injector was publisched before. (ID THPPO022 on the SRF09 Berlin.) This cavity is being fabricated in Jefferson Lab. In this paper the ideas of the redesign of the further parts of the SRF-gun2008 will be presented. The most important issue is the special design of half-cell and choke filter. The cathode cooler is also slightly changed, which simplifies the installation of the cathode cooler in the cavity. The next update is the separation of input and output of the liquid nitrogen supply, for the purpose of the stability of the N2 pressure as well as the better possibility of temperature measurement. Another key point is the implementation of the superconducting solenoid inside the cryomodule. The position of the solenoid can be accurately adjusted with two stepmotors, which is thermally isolated to the solenoid itself.

TUPO019

Fabrication, Tuning, Treatment and Testing of Two 3.5 Cell Photo-Injector Cavities for the ELBE Linac

405

A. Arnold, P. Murcek, J. Teichert, R. Xiang
HZDR, Dresden, Germany
G.V. Eremeev, P. Kneisel, M. Stirbet, L. Turlington
JLAB, Newport News, Virginia, USA

As part of a CRADA (Cooperative Research and Development Agreement) between Helmholtz-Zentrum Dresden-Rossendorf (HZDR) and Thomas Jefferson Lab National Accelerator Facility (TJNAF) we have fabricated and tested two 1.3 GHz 3.5 cell photo-injector cavities from polycrystalline RRR niobium and large grain RRR niobium, respectively. The cavity with the better performance will replace the presently used injector cavity in the ELBE linac*. The cavities have been fabricated and pre-tuned at TJNAF, while the more sophisticated final field tuning, the adjustment of the external couplings and the field profile measurement of transverse electric modes for RF focusing** was done at HZDR. The following standard surface treatment and the vertical test was carried out at TJNAF’s production facilities. A major challenge turned out to be the rinsing of the cathode cell, which has small opening (Ø10mm) to receive the cathode stalk. Another unexpected problem encountered after etching, since large visible defects appeared in the least accessible cathode cell. This contribution reports about our experiences, initial results and the on-going diagnostic work to understand and fix the problems.
* J. Teichert, et al., Proc. FEL 2010, Malmoe, Sweden, p. 453.
** V. Volkov, D. Janssen, Phys. Rev. ST Accel. Beams 11, 061302 (2008).

Poster TUPO019 [1.211 MB]

Paper	Title	Page
MOPO004	Modified SRF Photoinjector for the ELBE at HZDR	39
	P. Murcek, A. Arnold, H. Büttig, D. Janssen, M. Justus, P. Michel, G.S. Staats, J. Teichert, R. Xiang HZDR, Dresden, Germany P. Kneisel JLAB, Newport News, Virginia, USA
	The superconducting radio frequency photoinjector (SRF photoinjector) with Cs2Te cathode has been successfully operated under the collaboration of BESSY, DESY, HZDR, and MBI. In order to improve the gradient of the gun cavity and the beam quality, a new modified SRF gun (SRF-gun2008) has been designed. The main updates of the new cavity design for the new injector was publisched before. (ID THPPO022 on the SRF09 Berlin.) This cavity is being fabricated in Jefferson Lab. In this paper the ideas of the redesign of the further parts of the SRF-gun2008 will be presented. The most important issue is the special design of half-cell and choke filter. The cathode cooler is also slightly changed, which simplifies the installation of the cathode cooler in the cavity. The next update is the separation of input and output of the liquid nitrogen supply, for the purpose of the stability of the N2 pressure as well as the better possibility of temperature measurement. Another key point is the implementation of the superconducting solenoid inside the cryomodule. The position of the solenoid can be accurately adjusted with two stepmotors, which is thermally isolated to the solenoid itself.

TUPO019	Fabrication, Tuning, Treatment and Testing of Two 3.5 Cell Photo-Injector Cavities for the ELBE Linac	405
	A. Arnold, P. Murcek, J. Teichert, R. Xiang HZDR, Dresden, Germany G.V. Eremeev, P. Kneisel, M. Stirbet, L. Turlington JLAB, Newport News, Virginia, USA
	As part of a CRADA (Cooperative Research and Development Agreement) between Helmholtz-Zentrum Dresden-Rossendorf (HZDR) and Thomas Jefferson Lab National Accelerator Facility (TJNAF) we have fabricated and tested two 1.3 GHz 3.5 cell photo-injector cavities from polycrystalline RRR niobium and large grain RRR niobium, respectively. The cavity with the better performance will replace the presently used injector cavity in the ELBE linac. The cavities have been fabricated and pre-tuned at TJNAF, while the more sophisticated final field tuning, the adjustment of the external couplings and the field profile measurement of transverse electric modes for RF focusing* was done at HZDR. The following standard surface treatment and the vertical test was carried out at TJNAF’s production facilities. A major challenge turned out to be the rinsing of the cathode cell, which has small opening (Ø10mm) to receive the cathode stalk. Another unexpected problem encountered after etching, since large visible defects appeared in the least accessible cathode cell. This contribution reports about our experiences, initial results and the on-going diagnostic work to understand and fix the problems. * J. Teichert, et al., Proc. FEL 2010, Malmoe, Sweden, p. 453. ** V. Volkov, D. Janssen, Phys. Rev. ST Accel. Beams 11, 061302 (2008).
	Poster TUPO019 [1.211 MB]