Background-electron Multiplication Research Articles

Penning neon laser with excitation by background-electron multiplication wave

The Penning neon laser was studied in a Ne-H2 mixture excited by a transverse discharge. Theoretical modeling allowed the conclusion that the laser active medium was excited due to the background-electron multiplication wave passed through the discharge gap.

Pumping of lasers and lamps by discharges based on the background-electron multiplication waves

Experimental realization of a new discharge type, i.e., the discharge representing a background-electron multiplication wave, is considered. Experimental and theoretical data illustrating the applicability of this discharge type to excitation of laser and lamp radiation sources are presented.

Penning neon laser excited by background-electron multiplication wave

The Penning neon laser was studied in a Ne-H2 mixture excited by a transverse discharge. Theoretical modeling allowed the conclusion that the laser active medium was excited due to the background-electron multiplication wave passed through the discharge gap.

On the initial stage of a subnanosecond pulsed breakdown of high-pressure gas discharge gaps

The model of background electron multiplication is used for deriving the time dependence of ionization, which correctly describes experiments on initiation of a homogeneous high-voltage subnanosecond pulsed breakdown under a gas pressure on the order of ten atmospheres in a discharge gap ∼1 mm.

Possibility of lasing on the Ne transitions in the afterglow of a background electron multiplication wave

The possibility of lasing with the Ne + H2 Penning mixture in the afterglow of a background electron multiplication wave that emerges in the presence of a nanosecond high-voltage pulse with the subnanosecond leading edge across the discharge gap filled with the atmospheric-pressure gas is considered. The needed nonuniformity of the field is created with small-curvature-radius electrodes. It is demonstrated that lasing is possible at a relatively small (several centimeters) length of the active medium.

On the possibility of pumping Xe2* lasers and VUV lamps in the afterglow of a background-electron multiplication wave

It was shown earlier that the ionisation propagation in a gas at about the atmospheric pressure may proceed due to the multiplication of the existing electrons with a low background density rather than the transfer of electrons or photons. We consider the feasibility of using the plasma produced in the afterglow of this background-electron multiplication wave for pumping plasma lasers (in particular, Xe2* xenon excimer lasers) as well as excilamps. Simulations show that it is possible to achieve the laser effect at λ≈172 nm as well as to substantially improve the peak specific power of the spontaneous radiation of xenon lamps.

Simulation of the time of transit of a discharge gap by a background electron multiplication wave

Two-dimensional simulation of plasma spread via multiplication of low-density background electrons is performed. It is shown that the velocity of the wave grows as it approaches the opposite electrode. The time taken for the multiplication wave to cross the helium-, nitrogen-, or xenon-filled gap between the capacitor plates is calculated as a function of the field strength. As follows from estimates, the recently found fact that the beam current in gas media peaks earlier than in a vacuum may be explained by a rapid travel of the electron multiplication wave through the background ionized by the precursor pulse.

Energy distribution of runaway and fast electrons upon nanosecond volume discharge in atmospheric-pressure air

Nanosecond space discharge in a gas-filled diode is promising for pumping of lasers and high-power lamps. The space charge formed in the absence of an additional preionization source has a few advantages. The energy distributions of the beam electrons and the X-ray spectrum are determined. It is demonstrated that several high-energy electron bunches are formed in such a discharge. The main contribution to the beam current measured behind the foil is related to the runaway electrons, which have energies of tens or hundreds of kiloelectronvolts (supershort avalanche electron beam (SAEB)). Fast electrons with energies of several or tens of kiloelectronvolts are responsible for the generation of the soft X rays in the discharge gap. Anomalous electrons whose energy is higher than the voltage across the gap provide for a minor (less than 5%) contribution to the beam current. The generation time of these electrons is equal to the SAEB generation time accurate to 0.1 ns. It is demonstrated that the anomalous electrons can be generated owing to the acceleration in the presence of the field in front of the moving background-electron multiplication wave. The spectra of the X-ray radiation generated by the fast electrons in the volume are calculated.

Escaping electrons and discharges based on the background-electron multiplication wave for the pumping of lasers and lamps

A review of the recent papers devoted to the phenomena realized upon nanosecond discharges in dense gases pumped with high-voltage pulses with subnanosecond edges is presented. The following problems are considered: (i) the dynamics of the fast (including escaping) electrons that provide for the background ionization of the dense gas, (ii) the propagation of the background-electron multiplication wave, and (iii) the discharges based on the background-electron multiplication wave. It is demonstrated that discharges based on the background-electron multiplication wave are promising for lasing at transitions that were shown to be involved in lasing in dense gas upon electron-beam pumping and in the afterglow of a pulsed discharge. In particular, they are promising for pumping excimer and exciplex lasers. In addition, such discharges can be used in excilamps that generate high-power spontaneous pulsed radiation.

Instability of the Background Electron Multiplication Wave Front

The initial stage of the development of instability in the front of an ionization wave, which is related to the multiplication of electrons at their small background density, is theoretically described. An analytical expression is obtained for the growth rate of small perturbations as a function (universal for the given gas) of the reduced field strength E/p (where E is the electric field strength and p is the gas pressure). The rate of instability development is calculated for helium, xenon, nitrogen, and sulfur hexafluoride. A new criterion of streamer formation is found.

Mechanism for the streamer propagation toward the anode and cathode due to background electron multiplication

A simple mechanism for the propagation of an ionization wave in a dense gas due to the multiplication of background electrons in a nonuniform electric field is proposed. The mechanism does not depend on the sign of the field projection onto the streamer propagation direction. The streamer propagation is caused by the enhancement of the electric field at the streamer head. It is shown that, in a prebreakdown field, the intense multiplication of electrons takes place in both electropositive and electronegative gases. The prebreakdown multiplication can provide a fairly high density of background electrons; this allows one to treat the background as a continuous medium when considering streamer propagation as a multiplication wave. The initial ionization is enabled by the natural background of ionizing radiation and cosmic rays. An analytical expression for the velocity of the ionization front is obtained based on a simple equation for the multiplication of background electrons. This expression is in good agreement with numerical simulations performed within both a simple model of background electron multiplication and a more comprehensive drift-diffusion model. In particular, the drift-diffusion model predicts the propagation of the ionization front from a small-radius anode to the cathode due to the multiplication of background electrons. The velocity of the ionization wave front is calculated as a function of the electric field at the streamer head for helium, xenon, nitrogen, and sulfur hexafluoride. It is shown that some features of streamer propagation (e.g., its jerky motion) can be related to the recently found nonmonotonic dependence of ionization frequency on the electric field.

The velocity of streamer propagation toward anode and cathode in He, Xe, N2, and SF6

A simple mechanism of ionization spreading in a dense gas, based on the background electron multiplication wave in an inhomogeneous electric field, is considered. This process is independent of the sign of the field projection onto the direction of propagation. An analytical expression for the velocity of the ionization front propagation is obtained, which agrees well with the results of numerical calculations performed using both the simple background electron multiplication model and a detailed diffusion-drift theory. The ionization wave front velocity as a function of the field strength at the streamer boundary has been tabulated for He, Xe, N2, and SF6. Some peculiarities observed in the motion of streamers, such as the velocity jerks, can be related to the recently discovered nonmonotonic dependence of the ionization rate on the field strength.