Electron Cooling and Accumulation of 200-MeV Protons at Fermilab

Experimental measurements have been made of the cooling of 200-MeV protons by an electron beam of 1 to 3 A and an energy of 110 keV. These experiments are an extention of earlier measurements on the cooling of 115-MeV protons and were performed in the Fermilab experimental proton storage ring. At 200 MeV the proton beam lifetime in the storage ring is extended from 10 to 4000 sec with electron cooling. The cooling times with an electron beam current of 1 A were approximately 2 sec for momentum and 5 to 10 sec for transverse cooling of the proton beam. For proton intensities of approximately 2 × 106 particles, the six-dimensional phase-space density Qf the proton beam was increased by a factor of 2 × 105. These results and data on equilibrium proton distributions and frictional forces are in reasonable agreement with the theoretical predictions. In addition, the accumulation of successive "hot" batches of protons into a cold core, i.e. stacking, has been demonstrated.