LINAC2014 - List of Authors (Horvitz, Z.)

Paper

Title

Page

Superconducting Accelerating Cavity Pressure Sensitivity Analysis and Stiffening

373

J. Rodnizki, Y. Ben Aliz, A. Grin, Z. Horvitz, A. Perry, L. Weissman
Soreq NRC, Yavne, Israel
G.K. Davis
JLab, Newport News, Virginia, USA
J.R. Delayen
ODU, Norfolk, Virginia, USA

The SARAF Prototype Superconducting Module (PSM) houses six 176 MHz Half Wave Resonators(HWR). The PSM accelerates protons and deuterons from 1.5 MeV/u to 4 and 5.6 MeV. The HWRs are highly sensitive to the coolant liquid Helium pressure fluctuations which limit the available beam power to 2kW per cavity out of 4kW RF amplifier and coupler and so might limit the available beam current to 2mA depending on the output energy. The flat shape of the cavity along the beam line in the area of the high electric field generates the high sensitivity of the Eigen mode frequency to helium pressure. The evaluated cavity sensitivity is full consistent with the measured values. It was explored that the tuning system (the fog structure) has a significant contribution to the cavity sensitivity. By using ribs or by modifying the rigidity of the fog we may reduce the HWR sensitivity by a factor of 3. This analysis is applied to study the stresses on the cavity during cool down and warm up to avoid plastic deformation as the Niobium yield is an order of magnitude lower in room temperature.

WEIOB02

SARAF Phase-I Proton / Deuteron Linac Beam Operation Status

770

A. Kreisel, A. Arenshtam, Y. Ben Aliz, D. Berkovits, Y. Buzaglo, O. Dudovich, Y. Eisen, I. Eliyahu, G. Feinberg, I. Fishman, I.G. Gertz, A. Grin, S. Halfon, Y.F. Haruvy, T. Hirsch, D. Hirschmann, Z. Horvitz, B. Kaizer, D. Kijel, J. Luner, I. Mor, J. Rodnizki, G. Shimel, A. Shor, I. Silverman, D. Vartsky, L. Weissman, E. Zemach
Soreq NRC, Yavne, Israel

SARAF Phase-I linac is the first accelerator to demonstrate acceleration of variable energy 2 mA CW proton beam. Such intense beam is used in SARAF Phase-I to irradiate a liquid lithium jet target for nuclear astrophysics studies. Several improvements were necessary to allow beam operation with such high current. The improvements include a DC bias that was introduced on the cavity RF coupler to reduce coupler heating. A new slow chopper was commissioned to enable increase the current by increasing the duty cycle with fewer changes in the beam optics. A beam dump was developed to allow beam studies of a 2 mA CW proton beam. The beam dump is based on tungsten pins which distributes, by radiation, the high beam power over a large area which is then easily water cooled. While most of beam tuning is done using a low intensity pilot beam, some nondestructive methods were studied to monitor the high intensity beam. These include a current transformer and a residual gas monitor (RGM) to monitor beam transverse distribution. Additional valuable information about the beam current and energy is gained from measurements of the nuclear reaction products of the proton on lithium targets.

Slides WEIOB02 [3.027 MB]

Paper	Title	Page
MOPP134	Superconducting Accelerating Cavity Pressure Sensitivity Analysis and Stiffening	373
	J. Rodnizki, Y. Ben Aliz, A. Grin, Z. Horvitz, A. Perry, L. Weissman Soreq NRC, Yavne, Israel G.K. Davis JLab, Newport News, Virginia, USA J.R. Delayen ODU, Norfolk, Virginia, USA
	The SARAF Prototype Superconducting Module (PSM) houses six 176 MHz Half Wave Resonators(HWR). The PSM accelerates protons and deuterons from 1.5 MeV/u to 4 and 5.6 MeV. The HWRs are highly sensitive to the coolant liquid Helium pressure fluctuations which limit the available beam power to 2kW per cavity out of 4kW RF amplifier and coupler and so might limit the available beam current to 2mA depending on the output energy. The flat shape of the cavity along the beam line in the area of the high electric field generates the high sensitivity of the Eigen mode frequency to helium pressure. The evaluated cavity sensitivity is full consistent with the measured values. It was explored that the tuning system (the fog structure) has a significant contribution to the cavity sensitivity. By using ribs or by modifying the rigidity of the fog we may reduce the HWR sensitivity by a factor of 3. This analysis is applied to study the stresses on the cavity during cool down and warm up to avoid plastic deformation as the Niobium yield is an order of magnitude lower in room temperature.

WEIOB02	SARAF Phase-I Proton / Deuteron Linac Beam Operation Status	770
	A. Kreisel, A. Arenshtam, Y. Ben Aliz, D. Berkovits, Y. Buzaglo, O. Dudovich, Y. Eisen, I. Eliyahu, G. Feinberg, I. Fishman, I.G. Gertz, A. Grin, S. Halfon, Y.F. Haruvy, T. Hirsch, D. Hirschmann, Z. Horvitz, B. Kaizer, D. Kijel, J. Luner, I. Mor, J. Rodnizki, G. Shimel, A. Shor, I. Silverman, D. Vartsky, L. Weissman, E. Zemach Soreq NRC, Yavne, Israel
	SARAF Phase-I linac is the first accelerator to demonstrate acceleration of variable energy 2 mA CW proton beam. Such intense beam is used in SARAF Phase-I to irradiate a liquid lithium jet target for nuclear astrophysics studies. Several improvements were necessary to allow beam operation with such high current. The improvements include a DC bias that was introduced on the cavity RF coupler to reduce coupler heating. A new slow chopper was commissioned to enable increase the current by increasing the duty cycle with fewer changes in the beam optics. A beam dump was developed to allow beam studies of a 2 mA CW proton beam. The beam dump is based on tungsten pins which distributes, by radiation, the high beam power over a large area which is then easily water cooled. While most of beam tuning is done using a low intensity pilot beam, some nondestructive methods were studied to monitor the high intensity beam. These include a current transformer and a residual gas monitor (RGM) to monitor beam transverse distribution. Additional valuable information about the beam current and energy is gained from measurements of the nuclear reaction products of the proton on lithium targets.
	Slides WEIOB02 [3.027 MB]