Single-component plasma of photoelectrons

Ten-nanosecond pulses of photoelectrons liberated by intense UV laser pulses from a thin gold layer are captured into a single-component plasma that is ideally suited to cool antiprotons (p¯) for antihydrogen (H¯) production. Up to a billion electrons are accumulated using a series of laser pulses, more than are needed for efficient p¯ cooling in the large traps now being used for loading p¯ for H¯ production. The method is demonstrated within an enclosed vacuum space that is entirely at 4 K, and is thus compatible with the exceptional cryogenic vacuum that is desirable for the long-term storage of antihydrogen. The pitfalls of other electron accumulation methods are entirely avoided, including the particle heating and declining efficiency of field emission point loading, and the heat load and contamination of thermionic emission methods.