PICO SECOND RISE TIME PULSE GENERATION USING MARX GENERATOR WITH PEAKING CIRCUIT

Abstract

The work of picosecond rise time pulse generation using Marx generator with peaking circuit is presented. The 10 stage Marx generator is used to generate high voltage (140KV) 2nanosecond rise time pulse. The characteristics impedance of the Marx generator is 70ohm The peaking capacitor is developed in our laboratory to achieve the lower capacitance and also withstand higher voltage. The peaking capacitor is made using mixture of barium titanate and neoprene rubber in the ratio of 1:10 respectively. Barium titanate is piezoelectric material so it cracks during high voltages discharges due to stresses developed in it. Barium titanate is mixed with neoprene rubber which absorbs the piezoelectric stresses and prevents damaging of the capacitor. The peaking switch also developed which is used to sharpen the rise time of the pulse. The 50ohm resistor is used as load impedance. Simple 600mm length dipole antenna is used to radiate the picosecond rise time pulse. The radiated pulse is received by the D dot probe at 5 metre distance. The radiated frequency measured is 700MHz in the FFT spectrum. The rise time of 500 picosecond is calculated from the FFT peak frequency.