Abstract
The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory is an accelerator based neutron scattering facility. The SNS uses the large scale high energy superconducting linac (SCL) to provide high beam power utilizing hydrogen ion (H-) beams. For the diagnostics of high-brightness H- beam in the SCL, nonintrusive methods have to be developed. This paper describes design, implementation, theoretical analysis and experimental demonstration of a nonintrusive profile monitor system based on photodetachment, also known as laser wire, installed in the SNS-SCL. The SNS laser wire system is the largest of its kind with a capability of measuring both horizontal and vertical profiles of an operational H- beam at each of the 23 cryomodule stations along the SCL beam line by employing a single light source. Presently 9 laser wire stations have been commissioned which measures H- beam profiles at 9 different locations corresponding to energy levels of 200 MeV to 1 GeV. The laser wire diagnostics has no moving parts inside the beam pipe, causes no contamination on the superconducting surface, and can be run parasitically on an operational neutron production H- beam.
