Use of a wire scanner for monitoring residual gas ionization in Soreq Applied Research Accelerator Facility 20 keV∕u proton∕deuteron low energy beam transport beam line

B Vainas; I Eliyahu; L Weissman; D Berkovits

doi:10.1063/1.3670348

Use of a wire scanner for monitoring residual gas ionization in Soreq Applied Research Accelerator Facility 20 keV∕u proton∕deuteron low energy beam transport beam line

Rev Sci Instrum. 2012 Feb;83(2):02B712. doi: 10.1063/1.3670348.

Authors

B Vainas¹, I Eliyahu, L Weissman, D Berkovits

Affiliation

¹ SARAF, Soreq Nuclear Research Center, Yavne 81800, Israel.

PMID: 22380317
DOI: 10.1063/1.3670348

Abstract

The ion source end of the Soreq Applied Research Accelerator Facility accelerator consists of a proton∕deuteron ECR ion source and a low energy beam transport (LEBT) beam line. An observed reduction of the radio frequency quadrupole transmission with increase of the LEBT current prompted additional study of the LEBT beam properties. Numerous measurements have been made with the LEBT bream profiler wire biased by a variable voltage. Current-voltage characteristics in presence of the proton beam were measured even when the wire was far out of the beam. The current-voltage characteristic in this case strongly resembles an asymmetric diodelike characteristic, which is typical of Langmuir probes monitoring plasma. The measurement of biased wire currents, outside the beam, enables us to estimate the effective charge density in vacuum.