Characterization and Optimization of Bremsstrahlung X-ray Diodes

Investigations are underway at Sandia National Laboratories looking into characterization and optimization of bremsstrahlung x-ray diodes operating in the >10 MeV regime using the CHICAGO particle-in-cell code. These diodes typically use a hollowed-cathode geometry to form a circular beam on a high Z metal target. This paper will discuss driver target impedance matching, look at beam uniformity on target, estimate anode surface temperatures, and examine near and far-field dose predictions. Other cathode geometries such as a solid hemispherical ball will be considered as well. All geometries are designed to keep the anode surface temperature below 400^o C to prevent ion formation and beam pinching to the axis. Anode target geometry will be discussed including the advantages and disadvantages of specific materials such as titanium and tantalum. Comparisons will be made to previous Hermes III and RITS-6 experimental bremsstrahlung diodes data.