The Vacuum-System Of The Amsterdam Pulse Stretcher Ring, Amps

The construction of a combined electron stretcher and storage ring operating at energies up to 0.9 GeV has recently started in Amsterdam. The ring will improve the specifications of the existing Medium Energy Accelerator (MEA) Facility of the Institute for Nuclear Physics and High Energy Physics Research (NIKHEF). This manuscript presents a summary of the vacuum system design of the ring. In order to achieve a 1 h beam life-time the vacuum pressure with a stored beam will have to be in the low 10(-8) mbar range. The major gas source is due to synchrotron radiation causing desorption from the stainless steel vacuum chamber walls. Because of the beam induced r.f. fields smoothness of the magnet vessels, monitors, beampipes and bellows is essential. Clearing electrodes are foreseen in order to avoid instabilities caused by ions produced by the beam in the residual gas.