Helium-neon Mixture Research Articles

The electron temperature dependence of the effective recombination coefficient in an afterglow of a neon-helium mixture: P Lukac et al,Proc of 11th Internat Conf on Phenom in Ioniz Gases, Prague 1973, 33

The electron temperature dependence of the effective recombination coefficient in an afterglow of a neon-helium mixture: P Lukac et al,Proc of 11th Internat Conf on Phenom in Ioniz Gases, Prague 1973, 33

Experimental determination of the zero value of the phase characteristic of an active medium in a ring laser emitting at λ = 3.39 μ

An investigation was made of a resonance effect in a gas ring laser, which gave rise to a power peak in the opposite waves. The center of the peak corresponded to the zero value of the phase characteristic associated with the nonlinear dispersion of the medium. The theory of the effect and the results of the experiments carried out at λ = 3.39 μ were analyzed. A methane peak was used to measure the frequency shift of the center of the power peak relative to the center of the methane transition as a function of pressure in a helium-neon mixture.

On field adsorption, ionization rates and gas supply

The field ionization of a helium-neon mixture is analyzed to gain information about the imaging process in a field ion microscope. Quantitative measurements are performed on ionization rates, the number of jumps a helium atom performs before ionization and the fraction of helium atoms that escape ionization.

Clearing field effects in sealed glass spark chambers

The efficiency of spark chambers, consisting of sealed glass boxes filled with neon-helium mixture and having external metal electrodes, has been found to depend upon the rate of pulsing of the chambers. This effect is due to internal clearing fields, produced by the discharges themselves, which influence the whole chamber and not just the area around the spark. The fields are small, of the order of 1 V/cm, and are most likely to be caused by charge movement over the glass surface from the position of the originating discharge.

Measurements on field adsorption of neon and helium and the field ionization of a helium-neon mixture

The field ionization of a helium-neon mixture is investigated. The behavior can be explained in terms of field adsorption of neon. Experimental values for the binding energy, the adsorption rate and desorption rate are obtained. At high fields, field desorption of neon is observed. The enhancement of field ionization due to the rare-gas adsorption is measured.

Spectral method of measuring the concentrations of the components of a helium-neon gas mixture in a sealed tube

Spectral method of measuring the concentrations of the components of a helium-neon gas mixture in a sealed tube

High resolution optical spark chamber

An optical spark chamber was constructed with 3 mm gaps capable of operation at high pressures. With twenty atmospheres of a neon helium mixture, a resolution of about 70 μm was achieved, a considerable improvement over conventional chambers.

High resolution wire spark chamber

A wire spark chamber has been constructed with a wire spacing of eight wires per mm and a 1.2 mm gap. Operated at a pressure of 15 atm of a neon-helium mixture, it has been found to give a track position accuracy of better than 75 μm.

Pulsed generation in neon and neon-helium mixture

Pulsed generation in neon and neon-helium mixture

Direct measurement of the gain profile of a helium-neon mixture

The probe l ase r is a H e N e lase r operating at 1 = 0.63 g. The resona to r length is L = 120 ram. The resona tor is mounted on g l a s sce ramic p r i sms . The instability of this laser is less than 10 -8 per minute. The axial mode spacing of the resona tor is 1250 MHz. One of the resona tor m i r r o r s is cemented on a p iezoce ramic , which allows the resona to r length to be var ied by severa l wavelengths, The oscillation frequency at X = 0.63 # changes correspondingly by 1250 MHz. The scanning in te r fe romete r (Fig. 1) is used to control

Equipment for producing pure neon from a neon-helium mixture

Equipment for producing pure neon from a neon-helium mixture

Measurement of coherent-amplification coefficients of neon lines in a helium-neon mixture

Measurement of coherent-amplification coefficients of neon lines in a helium-neon mixture

Neon-helium mixture separation plant

Neon-helium mixture separation plant

Studies of decaying plasmas produced in neon and helium-neon mixtures

This paper reports simultaneous measurements of the time dependence of the intensities of spectral lines and that of the number density of atomic and molecular ions in decaying plasmas produced in neon and helium-neon mixtures. The measurements in neon resulting in the mobility value, μ o(Ne +) = 4.0 cm 2/V.s, at a gas temperature of 335°K, while the frequency of conversion of Ne + into Ne + 2 was found to be ν conv = 52 P 2 0 s −1. A study of the time dependences, during the neon afterglow, of the intensity of spectral lines originating from transitions from the 4 d levels strongly indicates that these levels are mainly populated by a recombination process involving Ne +. Analogous studies of the behavior of spectral lines originating from transitions from the 2 P and 3 P levels show that these energy levels are mainly populated by the dissociative recombination process Ne + 2 + e → Ne ∗ + Ne → 2Ne + hv. Preliminary studies on decaying plasmas produced in a helium-neon mixture confirmed the occurence of the processes He + 2 + Ne → Ne + + 2He and Ne + + 2He → (HeNe) + + He as previously postulated by Oskam. Moreover, these studies indicated the occurrence of the conversion process (HeNe) + + Ne + He → Ne + 2 + 2He.

Electron energy spectra in neon, xenon, and helium-neon laser discharges

Absolute measurements of the electron energy spectrum in a helium-neon mixture and in pure neon and xenon have been obtained by an energy analysis of a sample of electrons extracted through a small hole in the anode. The spectrum appears to be nearly Maxwellian for the lower pressures but deviates markedly from a Maxwellian at higher pressures. At higher pressures, the energetic part of the spectrum drops off faster, and one can describe this part by a Maxwellian of lower temperature than that for the bulk of the distribution. The average energies agree with those obtained from microwave measurements of the radiation temperature of the electrons if corrections are made for nonthermal distribution. Several production rates are computed with the help of the measured spectra, and they are related to the wall current, the power dissipation, and the possible electron depopulation of helium metastables. The production and destruction rates for the different parts of the energy spectrum have been formulated mathematically. A theoretical formula, which describes the actual spectra, has been derived for the faster part of the spectrum. For the helium-neon laser discharge we can say definitely that the de-excitation of helium metastables by electrons is negligible.

Collision-Induced Transitions within Excited Levels of Neon

The interaction of an intense optical-maser field with excited atoms in a gas discharge leads to a considerable change in the population of those levels which are resonant at the maser frequency. This will cause a change in the population of other levels that are connected to the maser levels through collision-induced nonradiative as well as radiative transitions. Using the 1.15-\ensuremath{\mu} optical maser, these effects have been studied in detail for the $2s$ levels of neon where the changes are completely due to collisions. By analyzing the intensity changes in spontaneous emission originating from a gas-discharge cell placed within the maser resonator, we have observed the approach to a partial thermalization of two closely spaced levels. In this way we have been able to obtain the atomic-collision cross section for excitation transfer between the $2{s}_{2}$ and $2{s}_{3}$ levels. In pure neon this has been found to be ${\ensuremath{\sigma}}_{23}=(2.3\ifmmode\pm\else\textpm\fi{}0.3)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}16}$ ${\mathrm{cm}}^{2}$. For a helium-neon mixture the measured cross section is ${\ensuremath{\sigma}}_{23}=(1.8\ifmmode\pm\else\textpm\fi{}0.3)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}16}$ ${\mathrm{cm}}^{2}$. The experimental method used to determine these cross sections eliminates the uncertainties caused by the effects of electron-atom collisions and radiative cascade. These techniques also yield the ratio of the Einstein coefficients for the transitions $2{s}_{2}\ensuremath{\rightarrow}2{p}_{10}$ and $2{s}_{3}\ensuremath{\rightarrow}2{p}_{10}$. The measured ratio is $\frac{{A}_{2}}{{A}_{3}}=3.0\ifmmode\pm\else\textpm\fi{}0.4$.

Spectroscopic Investigation of the Helium—Neon Molecule

When a discharge is excited in a helium—neon mixture a band spectrum appears that is absent in the spectra of the separate gases. This spectrum has been attributed to the HeNe molecule. Although investigated here under fairly high resolution, the spectrum was not completely analyzed. However, substitution of 3He for 4He resulted in isotopic shifts in agreement with those calculated for the rotational structure of a diatomic HeNe molecule. Investigation of the spatial distribution of intensity of the atomic and molecular radiation in the cathode region of a dc discharge in a helium—neon mixture and of its behavior under a superimposed microwave field yielded an indication of the origin of the molecular spectrum. The molecular ion HeNe+ is evidently formed by the reaction He++Ne+X→HeNe++X and then recombines partially into bound states. The molecular radiation observed is thus attributed to transitions between weakly bound states of the neutral molecule HeNe populated from above by electron—ion recombination.

Decay Rates of Metastable Helium Atoms and Laser Enhancements in Afterglow Period

The decay rates of the singlet and the triplet metastable atoms of helium and those of the helium-neon mixture are measured by an absorption method. The absorption tube is excited by the pulsed r.f. which is the same as the pulse operation of the laser. The afterglow of the neon line corresponding to the 2p4–1s4 transition is measured simultaneously. From the decay of the triplet metastable helium atoms and the decay of neon line in the afterglow, the enhancement of the 1.153µ laser oscillation in the afterglow period is investigated. Because the decay of the singlet metastable helium atoms is faster than that of the triplet metastable helium atoms, the visible laser oscillation at 6328Å is not enhanced in the afterglow period.

The quenching of light by microwaves incident on a negative glow plasma in a cold cathode glow discharge in a helium-neon mixture

We study non-equilibrium quantum dynamics of the single-component scalar field theory in 1+1 space–time dimensions on the basis of the Kadanoff–Baym equation including the next-to-leading-order (NLO) skeleton diagrams. As an extension of the non-relativistic case, we derive relativistic kinetic entropy at the first order in the gradient expansion of the Kadanoff–Baym equations. The derived entropy satisfies the H-theorem. Next we perform numerical simulations in spatially homogeneous configurations to investigate thermalization properties of the system by evaluating the system entropy. We find that at later times the kinetic entropy increases approaching the equilibrium value, although the limited time interval in the early stage invalidates the use of it.

Steady-State Output Power of a Laser as a Function of the Single-Pass Gain

An expression for the output power of a laser in terms of the measured single-pass gain is discussed for two cases: homogeneously and inhomogeneously broadened spectral lines. The results are applied to the 6328-Å laser line in the helium-neon mixture, but only an order-of-magnitude calculation is possible because of the lack of data. Finally, several of the assumptions made during the derivation are discussed.