The SNS linac wire scanner system

The linac wire scanner system for the Spallation Neutron Source (SNS) at Oak Ridge, TN, calls for 5 units in the medium energy beam transport (MEET), 5 in the drift tube linac (DTL), 8 in the coupled cavity linac (CCL), and 13 in the high energy beam transport (HEBT). The actuators are a custom design fabricated by Huntington Mechanical Laboratories. Four different strokes are required to cover the above areas. The electronics are designed and fabricated by Los Alamos National Laboratory (LANL). In this paper we will discuss the design of the actuators and the electronics, positioning accuracy tests of the actuators, and also show results from beam measurements taken during the MEET commissioning at Oak Ridge National Laboratory.

Overview

In the Spallation Neutron Source (SNS) facility, H beams will be accelerated to 2.5 MeV in an RFQ, to 87 MeV in a drift tube linac (DTL), to 186 MeV in a coupled cavity linac, and finally to 1000 MeV in a superconducting linac (SCL). The 60-Hz, 1-ms, 36-mA peak-current beam pulses are chopped into 690-ns long segments with a 1 µs period to give an average current of 1.4 mA and an average beam power of 1.4 MW.