## 4 Discussion  
In order to verify the simulation results, an experimental setup has been made. The results obtained in the simulations have been compared to measurements at an 8-stage Marx generator with similar parameters, as shown in the circuit in Figure 3. Likewise, it features a damping resistor \(\mathrm{R_{D}}\)[10]. Figure 24 shows the charging current and the charging voltage at the charging input terminal of an 8-stage Marx generator. The on-time of the solid-state switches is 22 \(\mathrm{\SIUnitSymbolMicro s}\). The measurement results fit very well with the simulation results shown in Figure 13 with respect to the charging voltage and charging time and as well as the ringing after charging. Simulation and measurements differ slightly with respect to damping. However, an exact fit of the simulations to measurements was not the goal of the investigations. Figure 23: Equivalent circuit showing current paths. Figure 25 shows the measured charging voltage after inserting a diode in series to the charging coil L15. It suppresses the ringing as expected. The measured voltage across the damping resistor exhibits a similar shape as the current in Figures 20 and 21 and shows very well the change of the current path of the common-mode current during charging and the finding that damping of the common-mode current occurs mainly after charging of the generator. For the eight-stage Marx generator, the power dissipation in the damping resistor in the order of 50 W is small compared to the average power which the generator delivers to the load. This power is, on average, 12 kW when operating the generator at a charging voltage of 1 kV per stage and 500 Hz pulse repetition rate. However, the total power of the Marx generator and the energy stored in the cores of the current compensated chokes both scales with the number of stages. The energy that is dissipated in the damping resistor scales with the number of current-compensated chokes, which is one less than the number of stages. Hence, the ratio of average power dissipated in and the total average power of the generator scales with. For a large number of stages, the ratio can be approximated as a linear dependency of the number of stages. Especially for a Marx generator with a larger number of stages, the heat dissipation at the damping resistor needs  
Figure 24: Measured charging voltage and the charging current at the charging input terminal of an 8-stage Marx generator, on-time of the solid-state switches: 22 μs [10]. Figure 25: Measured charging voltage and the charging current at the charging input terminal of an 8-stage Marx generator with a diode in series to, voltage across the damping resistor, on-time of the solid-state switches: 22 μs [10]. to be considered. Moreover, with a damping resistor of \(\mathrm{R_{D}}=20\) Ohm, the amplitude of the common-mode current is significantly higher than for the case without a damping resistor. In the presented simulations, the peak value of the common-mode current with \(\mathrm{R_{D}}=20\) Ohm is 3.2 A under steady-state conditions, and without a damping resistor, only 1.8 A. In the latter case, the current through the current-compensated chokes decays to zero right after charging the capacitors. As a consequence, the cores of the current-compensated chokes in the charging path can be designed smaller. For a design omitting the damping resistor \(\mathrm{R_{D}}\), the power supply needs to be designed in such a way that it can cope with a floating potential at its ground-side terminal. This can be accomplished either by static or transient insulation of the power supply versus ground. Static insulation may comprise a transformer as an insulating element. Dynamic insulation may be achieved by adding a second charging coil \(\mathrm{L_{Res}}\) also to the ground-side current path between the voltage source V1 and the pulse generator and distributing the total inductance equally among both coils.