Phase Displacement Acceleration of High Intensity Stacks in the CERN ISR

In the ISR high intensity stacks of more than 25 A are accelerated by phase displacement from 26.6 to 31.4 GeV/c. Phase displacement is the only known means of accelerating stacks of such large momentum spread (Δp/p = 3%) with the existing low power RF system. Acceleration in this way may produce loss of intensity due to RF and power supply magnet noise, momentum blowup of the stack, closed orbit and working line variations, and changes in the RF bucket size while traversing the stack. The existing instrumentation allows close control of all relevant parameters during acceleration and has resulted in reducing the intensity losses to as little as 10%. In this way, luminosities significantly in excess of the ISR design luminosity are achieved in an operational way, making 31.4 GeV/c one of the standard ISR momenta for physics data taking and giving an equivalent nomentum of greater than 2,000 GeV/c when related to stationary target machines.