LSP simulations of the paraxial diode and comparisons with experimental data

The standard paraxial diode is used extensively at AWE to field of variety of hydrodynamic experiments. This diode will also be used in the short term on IVA machines currently being developed for use in the forthcoming HRF. The short term goal for the HRF is to produce 600 R @ 1 m in a 5 mm spot on a 14 MVolt IVA machine. In support of this HRF proposal 2-D PIC simulations using the code LSP have been undertaken to understand the physics of electron beam propagation in the diode. Currently the code is being benchmarked against experimental data from two machines: E-minor and Mogul-E. Some preliminary comparisons will be made in terms of X-ray dose and radiographic spot size. Another important benchmarking parameter is the net current has an important effect upon the behavior of the electron beam. The beam electrons oscillate about the beam axis according to the betatron wavelength with the first focal point of the beam dependent upon the net current established within the gas cell. In this paper we discuss LSP predictions for diodes fielded at voltages up to 10 MV and compare findings with currently available experimental data.