Hauri, C. P.

Paper	Title	Page
MOPPH055	Low Thermal Emittance Measurements at the PSI-XFEL Low Emittance Gun Test Facility	110
	Y. Kim, Å. Andersson, M. Dach, R. Ganter, C. Gough, C. P. Hauri, R. Ischebeck, F. Le Pimpec, M. Paraliev, M. Pedrozzi, T. Schietinger, B. Steffen, A. F. Wrulich PSI, Villigen
	To check performance of a planned low emittance gun (LEG) for the PSI XFEL project, a 500 kV pulsed diode based gun test facility was constructed at PSI in 2007. The gun was specially designed to have an adjustable gap between the cathode and the anode, and to allow extensive high gradient tests. Since the electron temperature at the cathode determines the minimum achievable slice emittance, we concentrated our efforts to measure the thermal emittance of a diamond turned copper cathode and stainless steel ones. To minimize emittance growth due to space charge effects, a single bunch with a charge of about 0.6 pC was used to characterize the beam. Since the experimental setup does not include an RF cavity, there was no dilution effects due to the non-linearity of the RF field. After optimizing the pulser to get a stable operation at 40 MV/m with the copper cathode, we could get about 0.2 mm.mrad range thermal emittance for a laser spotsize at the cathode of about 0.330 mm (RMS). In this paper, we report on our realistic thermal emittance measurements with copper and stainless steel cathodes at the LEG facility, which are much smaller than measured results by other laboratories.
	Slides
TUPPH001	Comparison of High Gradient Achievement for Different Metals in DC and Pulsed DC Mode	227
	F. Le Pimpec, R. Ganter, C. Gough, C. P. Hauri, M. Paraliev PSI, Villigen
	For the PSI XFEL project, an advanced high gradient low emission gun is under development. Reliable operation with an electric field preferably above 125MV/m at a 4mm gap, and in presence of an UV laser beam, has to be achieved in a diode configuration in order to minimize the emittance dilution due to space charge effects. In the first phase, a DC breakdown test stand was used to test different materials with different preparation methods at voltages up to 100kV. In addition high gradient stability tests were also carried out over days in order to prove reliable spark-free operation with a minimum dark current. In the second phase, electrodes with selected materials were installed in the 250ns FWHM, 500kV electron gun and tested for high gradient breakdown and for quantum efficiency using a 266nm UV laser