Efficiency of the Fermilab Electron Cooler's Collector

The newly installed Recycler Electron Cooling system (REC) at Fermilab [1] will work at an electron energy of 4.34 MeV and a DC beam current of 0.5 A in an energy recovery scheme. As a part of the Electron cooling project, the efficiency of the collector for the REC was optimized at a dedicated test bench to the level of relative current losses of 5·10^-6. The paper discusses the test bench measurements for several distributions of a transverse magnetic field in the collector cavity.