Numerical Simulation And experimental Measurement Of pulse generation in coaxial Forming lines

In the SINUS family of pulsed, high current electron beam accelerators, the energy stored within a coaxial forming line (usually oil-insulated) is delivered to a load by means of a high voltage pressurized spark gap switch. For better matching to the load, a transmission line having a nonuniform wave impedance may be included between the switch and the load. Numerical simulation of the system described above has been performed with the use of 2.5D version of 2.5 and 3D, fully electromagnetic PIC-code KARAT. Geometrical parameters of several SINUS accelerators were used. Actual spatial configurations of the gas switch were considered, but the time dependence spark resistance between the electrodes was included as a variable. The obtained results are compared with actual pulse shapes from experiments. Conclusions are drawn about how the spark resistance as the function of time effects the pulse observed.