We have indigenously developed a twenty-stage vertical structure type Marx generator. At a matched load of 90-100 , for 25 kV DC charging, an output voltage pulse of 230 kV, and duration 150 ns is obtained. This voltage pulse is applied to a relativistic electron beam (REB) planar diode. For a cathodeanode gap of 7•5 mm, an REB having beam voltage 160 kV and duration 150 ns is obtained. Brass as well as aluminum explosive electron emission-type cathodes have been used.

In this paper, a ramp generator with programmable slope is presented. It consists of a high voltage step generator, followed by integrator. The capacitor and inductor in the integrator are designed such that they can be varied by a microcontroller. This circuit generates two bipolar ramps with fastest speed <1 ns and provides continuous speed variation from 6 to 30 ns for a ramp of 500 V. This is being developed as a part of automated streak camera for deflection of electron beam.

In this paper, a high power relativistic backward wave oscillator (BWO) experiment is reported. A 230 keV, 2 kA, 150 ns relativistic electron beam is generated using a Marx generator. The beam is then injected into a hollow rippled wall metallic cylindrical tube that forms a slow wave structure. The beam is guided using an axial pulsed magnetic field having a peak value 1 T and duration 1 ms. The field is generated by the discharge of a capacitor bank into a solenoidal coil. A synchronization circuit ensures the generation of the electron beam at the instant when the axial magnetic field attains its peak value. The beam interacts with the SWS modes and generates microwaves due to Cherenkov interaction. Estimated power of 2 MW in TM01 mode is observed.

Dispersion relation is obtained for an axisymmetric periodic slow-wave structure having arbitrary radial profile driven by an electron beam that is confined by a finite axial magnetic field. The slow-wave structure wall profile is expressed by a finite Fourier series sum, and field theory is utilized for derivation of the dispersion relation. Numerical analysis is carried out to study Cerenkov and slow cyclotron instabilities.

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