Magnetic compression and electrostatic reflection of very high /spl upsi/ γ electron beams

High current sub-ohm electron-ion diodes are produced in the highly converging fringe fields at one end of a magnetic solenoid. With these diodes, the magnetic compression of a very high /spl upsi/γ electron beam is investigated with and without the formation of a virtual cathode at the peak magnetic field. The magnetically focused beam transmission efficiency, area compression, and fluence gain are documented for up to 10:1 mirror ratios. When a virtual cathode is formed at the mirror peak, efficient electron beam reflexing is induced - thereby increasing the effective fluence through thin foils by a factor of six (or twice the optimum gain with conventional magnetic compression). Up to 3 MJ/g deposition in 0.1 mil copper foil is deduced from this data.