LINAC2014 - List of Authors (Kaizer, B.)

Paper	Title	Page
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]

THPP132	Warming Rate Reduction of the SARAF RF Couplers by Application of a High Voltage Dc Bias	1168
SUPG024	use link to see paper's listing under its alternate paper code
	B. Kaizer, Y. Ben Aliz, I. Fishman, J. Rodnizki, L. Weissman Soreq NRC, Yavne, Israel
	Warming up of the coupler region of the SARAF Half Wave Resonator (HWR) cavities was one of the main limiting factors for long operation at high RF field values. The warming effect is, most likely, associated with multipacting in the coupler region. We have tried to suppress the multipacting discharge in the couplers by application a DC bias to their inner conductors. A bias-T, element that conducts up to 4 kW of 176 MHz RF power and provides DC insulation of the coupler inner conductor, was designed and built for this purpose. First on-line operation showed that the DC bias indeed reduces dramatically the warming rates of most of the cavities by an order of magnitude. Today, coupler warming is no longer the main factor hindering accelerator operation.

Paper

Title

Page

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]

THPP132

Warming Rate Reduction of the SARAF RF Couplers by Application of a High Voltage Dc Bias

1168

SUPG024

use link to see paper's listing under its alternate paper code

B. Kaizer, Y. Ben Aliz, I. Fishman, J. Rodnizki, L. Weissman
Soreq NRC, Yavne, Israel

Warming up of the coupler region of the SARAF Half Wave Resonator (HWR) cavities was one of the main limiting factors for long operation at high RF field values. The warming effect is, most likely, associated with multipacting in the coupler region. We have tried to suppress the multipacting discharge in the couplers by application a DC bias to their inner conductors. A bias-T, element that conducts up to 4 kW of 176 MHz RF power and provides DC insulation of the coupler inner conductor, was designed and built for this purpose. First on-line operation showed that the DC bias indeed reduces dramatically the warming rates of most of the cavities by an order of magnitude. Today, coupler warming is no longer the main factor hindering accelerator operation.