A. A. Gurinovich

First lasing of a volume FEL (VFEL) at a wavelength range λ∼4–6 mm

First lasing of a volume free electron laser in the millimeter wavelength range is observed.

Progress of the volume FEL (VFEL) experiments in millimeter range

Use of non-one-dimensional distributed feedback in Volume Free Electron Laser gives possibility of frequency tuning in wide range. In present work, dependence of lasing process on the angle between resonant diffraction grating grooves and direction of electron beam velocity is discussed.

Experimental Study of an Axial Vircator With Resonant Cavity

Multicavity resonators for an axial vircator are developed and experimentally investigated. The frequency and radiation power are analyzed for different cathodes and anode meshes and varied cathode-anode gaps.

2-D Simulation and Experimental Investigation of an Axial Vircator

A method for 2-D simulation of an axial vircator with a resonance cavity is described. It uses a self-consistent solution of relativistic motion equations and Maxwell equations for scalar and vector potentials in the Coulomb gauge. The vector potential is represented as a superposition of resonator eigenmodes, where each eigenmode corresponds to a damping oscillator. Damping enables considering radiative energy losses from the open end of the resonator. Compliance of the simulation results with both published experimental studies and those performed by our team is demonstrated.

Time dependence of the intensity of parametric quasi-Cherenkov radiation produced by relativistic particles passing through electromagnetic (photonic) crystals

Abstract. Examining the temporal evolution of parametric quasi-Cherenkov terahertz radiation (PTR) produced by a relativistic charged particle passing through an electromagnetic crystal, we found that the duration of PTR pulses can be much longer than the particle flight time through the crystal. This enables a thorough experimental investigation of the time structure of parametric quasi-Cherenkov T-ray pulses generated by electron bunches available with modern accelerators. The complicated time structure of parametric radiation can also be observed in natural crystals in the x-ray range.

Generation of High-Current Electron Beams in Diodes With Large-Area Explosive Emission Cathodes

This paper reports the investigation of several types of large-area (20-40 cm2) explosive emission cathodes different in shape and emitting surface material. We concentrated on the cathodes with emitters made of dense fine-grained graphite and carbon-epoxy capillary arrays (multicapillary cathodes), but also considered a cathode with copper emitter. We experimented with planar and profiled (Ernst profile) emitters and a graphite ring-type cathode. The velocity of cathode plasma expansion, the stability of operation, and the homogeneity of generated beams are compared for different cathodes. The current density distribution over the beam cross section is examined using the beam imprint on the radiochromic film. The pepper pot method is used to find whether the beam is converging or diverging.

Cumulation of High-Current Electron Beams: Theory and Experiment

High-power electron beam cumulation in a relativistic vacuum diode with a ring-type cathode is considered. The term “electron beam cumulation” here means electron beam self-focusing accompanied with multifold beam current density increase on the beam axis compared to the average current density in the cathode-anode gap. Space-charge repulsion of electrons emitted by the explosive-emission plasma on the inner edge of the cathode is shown to be the origin of this cumulation mechanism. Current density in the vicinity of beam axis is evaluated for different cathode inner diameter values both numerically and experimentally. Cathode with eccentric apertures of different diameters is studied experimentally.

Experimental studies of Volume FELs with a photonic crystal

A Volume Free Electron Laser with a photonic crystal (crystal-like artificial periodic structure) formed by metallic threads (or foils) periodically strained inside a cylindrical waveguide is studied. Operation of Volume Free Electron Laser is discussed for different configurations of the photonic crystal.

Experimental Study of a Triode Reflex Geometry Vircator

A triode reflex geometry vircator operating within a 3.0–4.2 GHz range with efficiency up to 6% is developed and experimentally investigated. Shiftable reflectors are shown to enable frequency tuning and output power control. Radiation frequency and power are analyzed for different Cathode–anode gap values and varied reflector positions.

Magnetic Field Probe for Noninvasive Diagnostics of FCG Operation: Simulation and Experiment

2-D simulation of the flux compression generator (FCG) operation enables the calculation of the local magnetic field outside the FCG stator. The magnetic field strength at a certain point outside the FCG stator is shown to be dependent on the stator geometry, the electric current in the FCG circuit, and the snapshot of the armature position with respect to the observation point. The measurements made by the dedicated probe placed on the stator support shell confirm the simulation results. The distinguished points of the time-dependent magnetic field strength make it possible to place the magnetic field probe on the stator support shell for noninvasive diagnostics of the FCG operation.