A plasma thruster operating at high specific impulse ({ge} 3500 s) has been proposed to be based on electron-cyclotron resonance heating of whistler waves propagating on a plasma column on a magnetic hill. Calculations using a particle-in-cell code demonstrate that the distortion of the electron velocity distribution by the heating significantly reduces the flow of plasma up the field, greatly improving efficiency and reducing material interactions relative to a thermal plasma. These and other calculations are presented together with initial experiments on the plasma generated in the proposed device. The experiments are conducted in a magnetic field (3.3 {times} 10{sup {minus}2} T at resonance) and a magnetic mirror ratio of 5. Microwaves (0.915 GHz, <20 kW) are coupled to the plasma with a helical antenna. Vacuum field measurements are in good agreement with prediction. The desired plasma spatial distribution has not yet been achieved.

MGA is a gamma-ray spectrum analysis program for determining relative plutonium isotopic abundances. The isotopic composition of a plutonium sample is needed to calculate {sup 240}Pu{sub eff} that is used to interpret passive neutron coincidence measurements in units of absolute plutonium mass. MGA can determine plutonium isotopic abundances with accuracies better than 1% using a high-resolution, low-energy, planar germanium detector and measurement times ten minutes or less. MGA can include analysis of a second spectrum of the high-energy (300--600 keV) plutonium gamma rays that significantly improves the determination of {sup 240}P{sub eff} in high-burnup plutonium. For the high-energy gamma-ray measurements we have devised a new hardware configuration, so that both the low- and high-energy gamma-ray detectors are mounted in a single cryostat thereby reducing weight and volume of the detector systems. We describe the detector configuration and our experience with it using a combined neutron-gamma measurement system and the two-detector version of MGA. We discuss the sources of uncertainty in the determination of {sup 240}Pu{sub eff} and propose a new correlation for the determination of {sup 242}Pu.