Cherenkov Maser Research Articles

Operation of an X-band dielectric Cherenkov maser amplifier

A dielectric Cherenkov maser has operated as an amplifier at a frequency of 9.8 GHz. The amplifier consisted of an electron beam interacting with the TM01 mode of a cylindrical, dielectric lined waveguide with the rf input provided by a tunable (9–10 GHz), 10 kW magnetron. The dielectric constant of the liner was 10 with inner and outer radii of 1.0 and 1.27 cm, respectively. At electron beam voltage and current of 190 kV and 90 A, respectively, the measured power gain of the amplifier was 11 dB over a 21 cm interaction length with a pulse length of approximately 1 μs.

Plasma-filled dielectric Cherenkov maser

The effect of a background plasma on a dielectric Cherenkov maser is examined by solving the linearized, beam-plasma, dielectric-lined waveguide dispersion relation. The results indicate that introduction of the background plasma can produce a higher spatial growth rate for the beam-waveguide instability and can reduce the electric field at the dielectric surface when compared to the system with no background plasma present. It is also found that for some sets of waveguide parameters, the TM/sub 0n/ electromagnetic modes can propagate frequencies that are below the background plasma frequency in the system. These modes have a finite off frequency and are different from the Trivelpiece-Gould modes for the system.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Coaxial configuration of the dielectric Cherenkov maser

The linearized Lorentz force, continuity equation, and Maxwell's equations are used to calculate the system dispersion relation for a coaxial configuration of the dielectric Cherenkov maser. The system consists of two coaxial conductors lined with dielectric and an annular relativistic electron beam, which propagates between the two liners. The dispersion relation for the beam and dielectric-lined coaxial waveguide structure and the no-beam system that describes the dependence of the generated frequency on the coaxial waveguide parameters are presented. Using the linearized dispersion relation, the growth rate for the beam-TM/sub 0n/ waveguide mode instability is calculated in the strong-coupling tenuous beam limit.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Linear and nonlinear theory of Cherenkov maser operation in the intense relativistic beam regime.

The linear dispersion relation for axisymmetric TM modes in a cylindrical waveguide lined with a dielectric material and enclosing a thin annular electron beam is derived and solved. Approximate analytic solutions are obtained for both weak and moderate beam regimes. A model of nonlinear saturation is developed. This model, combined with the linear theory in the moderate beam regime, defines the most efficient and compact Cherenkov maser.