Beam Extraction System of the Synchrophasotron

Abstract

The creation of a beam extraction system of the Synchrophasotron (SPT) began in the seventies. The high efficiency of the extraction system met the usual requirements - receiving an intense beam and lowering the induced radiation of accelerator parts. But besides that we had to have high efficiency because the radiation around the SPT had to be reduced as there is no biological shield and experiments with internal beam was limited to 10 ppp. The alternative of an intricate and high cost radiation shield was to extract the beam with an efficiency of more than 90% and to transport it into the external experimental halls with suitable beam stoppers, which allowed the accelerator beam intensity to be increased at least by a factor of ten. A large transverse size of the SPT vacuum chamber permitted the extraction system to be constructed with such a high coefficient of extraction, in principle, without great complications. On the other hand, such a large volume of the magnetic field complicates considerably its stabilization at a level of 10 Wdivided10 X which is necessary for uniform beam extraction. As the power consumption of the SPT magnet during a flat top exceeds 10 MW, the problemmore » of suppression of guide field ripples to the above level has not been solved completely until now.« less