Simulation-based design of a pulse modulator for a 6 MeV medical LINAC using LTspice

This study presents the design and LTspice-based simulation of a pulse modulator for a 6 MeV medical linear accelerator (LINAC). The proposed circuit model integrates the key subsystems of the modulator, including the pulse forming network (PFN), switching stage, pulse transformer, and a simplified klystron load representation, enabling circuit-level evaluation of the pulse generation process. Simulation results show that the modulator can generate high-voltage pulses with a peak voltage of approximately 125 kV and a peak current of about 85 A. The resulting waveform exhibits rise and fall times of 1.1 µs and 1.6 µs, respectively, with a flat-top duration of approximately 5.05 µs at a repetition rate of 200 Hz. These pulse characteristics are consistent with the operational requirements of a 6 MeV medical LINAC. The results demonstrate the feasibility of the proposed modulator configuration at the circuit-simulation level and provide insight into the transient behavior of the integrated pulsed power system under simulated operating conditions, offering a useful reference for the preliminary design and analysis of high-voltage modulators for medical LINAC applications.