CRYOGENIC CONTROLS AT HERA

The 6.3 k;it proton Storage ring of the EERA project at DEW,wl I! contain 422 superconduct-in3 dipole and 224 quadru.x,lo rlsqcets. 'Three refrigerators produce supercrltizal hcli~m, which is fed into two transfer-1 in<%:; t h:ji:;ul~ply t-he superconduct.;ng nagr,ets in Che indiv~dusl sections of the ring through 16 cryogenic kxx<(~>;. R2frl.3"rators and boxes are control led by Idhe distrl?nte3 cryogenic control system. Ir: addition, the maqnPt test fiic 11 lty, the supcrcondticting cavities of the elect-rnn ring and the superconductlcg coil of the ZElJS cxperinent al IIERP, arc all fed by the central rcyfr i gt?r3tor ill? d controlled by the coxmon cryogenic c<>:11 t-01 s. This paper will. describe the principles of thrs,cunt r,li syt,t em and show spcxzia: s:ili:tion:; for the ind:~.iZuai tasks. I~roce~s c‘oriC:-01 for Cryogenlz Svslrmi; al. DF.SY--tlistnrical Backqround in Pi’/ ( i kt: ilqv of cryoyenic~; bc;an a! IXSY wit.:? the installatl3n (,! t hc PJITO experinont. As one of the first. txpr!rlm<:nt:; worldwide PI.UTO was equipped with a r;llilr,rc:l~rlductinq coi 1. The controls for the cryogenic eqr ~.zmi-nt wart; ' iairly simple. Many valves had to be opcri~i cd n~arr~:~il ly and 071-y a f.ex cor.irol loops were, nst a i 1 Pd. r!lc r:r>xi ~xper-imexlt witn a superconduc!ing coil at