Lithium beam energy-momentum correlations on PBFAII

Summary form only given. The correlation between the energy and canonical angular momentum of an Li beam generated with a 15-cm-radius applied-B-field ion diode on PBFAII is measured with a magnetic spectrometer for the purpose of determining the character of instabilities in the virtual cathode of the diode. The wave nature of instabilities expected in the virtual cathode of the diode should generate a correlation between the energy and transverse momentum of the beam. The data obtained typically show phase velocities of at least 3% of the speed of light. This is consistent with an ion mode instability in the virtual cathode. Various phase velocities, instability amplitudes, and divergences are used as input parameters for forward calculations with the PICDIAG beam transport program to compare with experimental results. Results show how source divergence can decrease the apparent phase velocity.