High-current-density subnanosecond electron beams formed in a gas-filled diode at low pressures

The formation of electron beams in a gas diode filled with various gases at low and medium pressures under the action of nanosecond voltage pulses has been studied. It is shown that subnanosecond pulses of the beam current in helium, hydrogen, neon, nitrogen, argon, methane, sulfur hexafluoride, krypton, and xenon can be obtained both at atmospheric pressure and at a pressure of several units or dozens of Torr. In particular, a beam current density above 2 kA/cm² behind the foil at a pulse duration (FWHM) of 250 ps has been obtained in helium-filled diode. On the passage from the regime of ultrashort avalanche electron beam formation to the vacuum diode regime, the beam current pulse amplitude decreases, while both the beam pulse duration (FWHM) and the pulse front width increase.     

A two-temperature model of pulse-periodic radiative discharge in high-pressure cesium vapor

A two-temperature model of pulse-periodic radiative discharge in high-pressure cesium vapor has been developed. Under high pressure and temperature conditions, a local thermodynamic equilibrium (LTE) in the discharge plasma is established at the electron temperature. Conditions in a nonequilibrium near-wall region are analyzed, where the state of plasma deviates from the LTE. The parameters of plasma during a discharge pulse and the radiation spectrum are calculated.     

Afterglow emission from xenon, krypton, and argon dimers in nanosecond volume discharge at elevated pressures

The emission characteristics of plasma of a volume discharge initiated by electron avalanche beams in heavy inert gases at pressures up to 1.5 bar have been studied. It is established that more than 90% of the energy radiated in the wavelength range from 120 to 850 nm is emitted from xenon, krypton, and argon dimers. In the case of excited xenon plasma, an output radiation power of ～300 kW and an energy of 45 mJ per cubic centimeter were obtained.     

Vibrational heat capacity of H<Subscript>2</Subscript> molecules in low-voltage discharge plasma with molecular hydrogen

We have studied the energy balance in weakly ionized plasma of a low-voltage discharge, which operates in immobile molecular hydrogen due to ionization of a small additive of cesium ions. The main components in the energy flux are determined, which are transferred by plasma electrons and due to the heat conductivity of H₂ molecules via the translational and rotational degrees of freedom, and (to the first approximation) an additional energy flux is evaluated that is transferred due to the vibrational heat conductivity. A criterion of smallness of the contribution due to vibrational heat conductivity to the energy balance of discharge plasma is formulated.     

Radiation characteristics of a dense cesium plasma in the visible range

Calculations are made of the radiation spectrum from a cesium plasma column. It is shown that this plasma may serve as a light source with a high proportion of visible radiation and an almost continuous spectrum. The visible spectrum is formed mainly by bright recombination 6P and 5D continua whose thresholds are shifted in the long-wavelength direction. Pis’ma Zh. Tekh. Fiz. 23, 40–45 (December 26, 1997)     

Efficient electric-discharge CO2 laser with a prepulse formed by a generator with an inductive energy storage device

Results are presented of experimental investigations of a CO₂ laser pumped by a self-sustained discharge from a generator with an inductive energy storage device and a semiconductor current chopper. It is shown that the energy stored in the inductance of the discharge circuit can form a prepulse capable of depositing most of the energy in the active mixture for nearoptimum values of the parameter E/p. A radiation energy of 3 J was achieved in an electricdischarge laser with a 0.181 liter active volume with a 17% efficiency relative to the energy stored in the capacitive storage device. Pis’ma Zh. Tekh. Fiz. 24, 57–61 (February 26, 1998)     

Increasing in the rate constant for dissociative attachment of electrons to hydrogen molecules by vibrational pumping during flow in a channel

An investigation is made of the electron-vibrational kinetics in a stream of vibrationally excited hydrogen flowing in a channel. It is shown that for suitably organized flow and a suitable choice of material for the channel walls, the rate constant 〈K _DA〉 for dissociative attachment of electrons to hydrogen molecules may be increased substantially. The effect is controlled by the mean vibrational energy 〈E _v ⁽⁰⁾ 〉 of the H₂ molecules entering the channel. Pis’ma Zh. Tekh. Fiz. 24, 69–75 (December 26, 1998)     

On the efficiency of emission from a plasma column in high-pressure pulse-periodic discharge in cesium

Spectral energy fluxes emerging from the surface of an axially symmetric column of inhomogeneous cesium high-pressure plasma have been calculated by direct integration of the radiation-transport equation. It is shown that, at a specified plasma temperature on the axis, irrespective of the radiation -formation mechanism and the radial distribution of the plasma parameters, the maximum energy fluxes arise when the radial optical thickness τ _R of the plasma column is close to unity. The asymptotic τ _R value, at which the discharge column radiation is the largest part of the Planck radiation, has been found.     

Recombination X-ray radiation from plasma liners

The possibility of creating a high-power X-ray source based on the recombination radiation mechanism has been studied and analyzed. The recombination X-ray radiation from neon, aluminum, and argon was obtained in experiments with plasma liners performed on the GIT-12 setup using a current pulse amplitude of ∼2.5 MA and a leading pulse front width of ∼300 ns. The obtained results show that the recombination mechanism of X-ray generation offers good prospects for the development of a high-power X-ray source with photon energies in the 7–20-keV range.