STATUS OF THE RAL FRONT END TEST STAND
The Front End Test Stand (FETS) under construction at RAL is a demonstrator for front end systems of a future high power proton linac. Possible applications include a linac upgrade for the ISIS spallation neutron source, new future neutron sources, accelerator driven sub-critical systems, a neutrino factory etc. Designed to deliver a 60mA H-minus beam at 3MeV with a 10% duty factor, FETS consists of a high brightness ion source, magnetic low energy beam transport (LEBT), 4-vane 324MHz radio frequency quadrupole, medium energy beam transport (MEBT) containing a high speed beam chopper plus comprehensive diagnostics. This paper describes the current status of the project and future plans.
INVESTIGATION OF SPACE CHARGE COMPENSATION AT FETS
In order to contribute to the development of high power proton accelerators in the MW range, and to prepare the way for an ISIS upgrade and to contribute to the UK design effort on neutrino factories, a front end test stand (FETS) is being constructed at the Rutherford Appleton Laboratory (RAL) in the UK [1]. The aim of the FETS is to demonstrate the production of a 60 mA, 2 ms, 50 pps chopped beam at 3 MeV with sufficient beam quality. The ion source and LEBT are operational [2] with the RFQ under manufacture. In the LEBT a high degree of space charge compensation (above 90%) and a rise time of space charge compensation around ~50 sec could be concluded indirectly from measurements. The FETS LEBT was updated to perform a detailed experimental analysis of space charge compensation as a more detailed knowledge is of interest for other high power proton projects. In this paper the results of the experimental work will be presented together with discussion of the findings in respect to beam transport.
Design and operation of a gas scattering energy spectrometer for the ISIS RFQ accelerator test stand
Abstract The design and operation of an apparatus to measure the beam energy of a radio frequency quadrupole (RFQ) particle accelerator, based on multiple scattering of H− ions in xenon gas, is described. The purpose of the apparatus is to confirm the mean energy and energy spread of the nominal 665 keV beam of H− ions from the ISIS RFQ. This RFQ, after comprehensive testing, is intended to replace the existing Cockcroft–Walton pre-injector on the ISIS spallation neutron source at the Rutherford Appleton Laboratory (RAL). The basis of the apparatus is a set of two cascaded assemblies each consisting of a gas scattering cell, a drift length and three small apertures, which together reduce the peak intensity of the beam current sufficiently to allow a semiconductor charged particle detector to be used to detect individual H− ions and measure their energies.