European Organization for Nuclear Research Cern - Sl Division Cern-sl-2000-033 Bt a Novel Eddy Current Septum Magnet for Sps Extraction towards Lhc and Cngs

A new East Fast-Extraction System is under construction in the SPS, to supply particles with a maximum batch length of 7.8 μs and 10.5 μs to the LHC and to CNGS (CERN Neutrino to Gran Sasso), respectively. The extraction septum magnets actually used at the SPS have been designed for slow extraction over several seconds and have large cooling and electrical power demands. A fast system of only 250 μs pulse duration has therefore been developed, using a half-sine excitation pulse with a superimposed third harmonic. The short pulse duration requires very thin magnetic yoke laminations, which can not easily be stamped and stacked. Profiting from a development for the LHC beam dump kicker magnets, the yoke is therefore built-up from tapewound cylindrical cores, employing 50 μm thick Si-steel tape. Thirty two cores are stacked longitudinally to produce a yoke of 3.2 meter length. The aperture is cut in radial direction into each cylinder. The cores are radial compressed by spring-loaded pistons inserted in strong stainless-steel frames to provide mechanical stability. The 5+1 mm-thick copper/iron septum is separated from the excitation current loop and acts as a passive eddy current screen. This allows separating the vacuum of the magnet from that of the circulating-beam channel, avoiding the need of using UHV material. This paper presents the magnet and generator prototype design as well as simulation and measurement results. Presented at EPAC2000, 26-30 June 2000, Vienna, Austria Geneva, Switzerland July 2000 A NOVEL EDDY CURRENT SEPTUM MAGNET FOR SPS EXTRACTION TOWARDS LHC AND CNGS . G.H. Schröder, W. Weisser, E. Carlier, J.H. Dieperink, L. Ducimetière, B. Goddard, C. Lazar, M. Mayer, E.B. Vossenberg and W. Weterings CERN, Geneva, Switzerland