Accurate values of the electron-impact ionization cross sections for the rare gases are needed in a variety of contexts. However, despite numerous investigations over many decades, uncertainty as to the correct values has persisted. The pioneering total-cross-section measurements of Rapp and Englander-Golden are generally regarded as the most reliable but no comprehensive study has independently verified their correctness. In this paper, measurements of electron-impact ionization cross sections of helium, neon, argon, krypton, and xenon are reported for energies ranging from the first ionization threshold to 1000 eV. These data confirm the essential correctness of Rapp and Englander-Golden's total measurements and at the same time provide a complete set of consistent absolute partial cross sections.

Determination of the absolute partial and total cross sections for electron-impact ionization of the rare gases

An overview is presented of experimental and theoretical research in the field of physics and engineering of singlet delta oxygen (SDO) production in low-temperature plasma of various electric discharges. Attention is paid mainly to the SDO production with SDO yield adequate for the development of an electric discharge oxygen–iodine laser (DOIL). The review comprises a historical sketch describing the main experimental results on SDO physics in low-temperature plasma obtained since the first detection of SDO in electric discharge in the 1950s and the first attempt to launch a DOIL in the 1970s up to the mid-1980s when several research groups started their activity aimed at DOIL development, stimulated by success in the development of a chemical oxygen–iodine laser (COIL). A detailed analysis of theoretical and experimental research on SDO production in electric discharge from the mid-1980s to the present, when the first DOIL has been launched, is given. Different kinetic models of oxygen low-temperature plasma are compared with the model developed by the authors. The latter comprises electron kinetics based on the accompanying solution of the electron Boltzmann equation, plasma chemistry including reactions of excited molecules and numerous ion–molecular reactions, thermal energy balance and electric circuit equation. The experimental part of the overview is focused on the experimental methods of SDO detection including experiments on the measurements of the Einstein coefficient for SDO transition and experimental procedures of SDO production in self-sustained and non-self-sustained discharges and analysis of different plasma-chemical processes occurring in oxygen low-temperature plasma which brings limitation to the maximum SDO yield and to the lifetime of the SDO in an electric discharge and its afterglow. Quite recently obtained results on gain and output characteristics of DOIL and some projects aimed at the development of high-power DOIL are discussed.

https://iopscience.iop.org/article/10.1088/0022-3727/40/2/R01/pdf

Physics and engineering of singlet delta oxygen production in low-temperature plasma

A pulsed electron beam and ion extraction method is used to measure normalized values of partial ionization cross sections for rare gases from threshold to 1000 eV. Cross sections obtained for singly ionized species are used to calibrate the mass transmission efficiency of the ion extraction/analyzer/detection system by the relative flow technique, and this mass transmission curve is then used to determine the absolute cross sections of the multiply ionized species. Total ion cross sections are found by summation of the individual partial cross sections with proper weighting for charge.

https://iopscience.iop.org/article/10.1088/0953-4075/21/6/014/pdf

Ionisation cross sections of rare-gas atoms by electron impact

A set of total cross sections for scattering of electrons by Ne, Ar, Kr and Xe has been evaluated over the energy range of about 20 to 3000 eV by means of the analysis of experiments and theories on total cross sections for elastic scattering, ionisation and excitation, and on differential cross sections for elastic and inelastic scattering. The total cross sections for scattering of electrons are evaluated by adding those for ionisation, excitation and elastic scattering and they are accurate to about 5-10%. They appear to be in very good agreement with the recent experimental results on total electron scattering of Wagenaar et al. (1978).

https://iopscience.iop.org/article/10.1088/0022-3700/12/6/016/pdf

Total cross sections for electron scattering by Ne, Ar, Kr and Xe

The negative‐ion species produced in O2 and some gases containing oxygen have been surveyed for various pressure and E/p conditions using an rf mass spectrometer coupled to an electron drift tube operating at pressures up to 5 torr. The gases studied include O2, CO2, H2O, and CO as well as the mixtures CO2–O2, H2O–O2, CO–O2 at moderate and high E/p. When CO2 is present, O2− and O− are converted to CO4− and CO3−, respectively. The rate coefficients for these reactions at 300°K are approximately 1.3×10−29 and 8×10−29 cm6/sec, respectively. When H2O is present, complex ions such as (H2O)n·O2−, (H2O)n·O− and (H2O)n·OH− are formed with n≤5. In CO–O2 and H2–O2 mixtures, ion destruction, consistent with associative detachment of O−, has been observed to proceed with rate coefficients of about 10−9 cm3 sec−1.

Survey of Negative‐Ion—Molecule Reactions in O2, CO2, H2O, CO, and Mixtures of These Gases at High Pressures

Measurements of the total cross sections for ionization of the rare gases argon, krypton and xenon under electron impact over the electron energy range up to 100 ev have been made with a Lozier apparatus. Measurements in argon show close agreement with those of Tate and Smith except in the low energy region, i.e. below about 2.5 ev.

Cross Sections for Ionization of the Inert Gases by Electron Impact

This paper describes a technique for the measurement of reignition voltage characteristics of spark gaps after the passage of a high current discharge. The initial discharge current is varied from 100 to 235 kA, and recovery-measurements in air at atmospheric pressure are given for 6 4 and 16 mm diameter tungsten electrodes and for 16, 19 and 76 mm diameter copper electrodes. The effects of gap length, current amplitude and electrode size and material are discussed, and it is observed that electrode size has a powerful influence upon the recovery process Gas temperatures are derived on the assumption that Paschen's law holds during the final recovery period.

Measurement of Reignition Voltage Characteristics for High Current Spark Gaps in Air

Measurements of attachment coeflficionte made with a Bradbury electron filter in oxygen for X/p varying between 4 and 30 volts/em/mm Hg show good agreement with recent data obtained with other techniques. Data on three-body coefficients were also obtained.

Measurements of Attachment Coefficients in Oxygen using an Electron Filter Technique

Spark discharges, in hydrogen, helium and He-H mixtures at atmospheric pressure, carrying 215 A rectangular wave current pulses or 3·5, 0·8 and 0·5 μsec durations, were studied with a photomultiplier technique. Using a photomultiplier-amplifier-CRO equipment in conjunction, with a spectrometer, the relative intensities, and their time variations, of some of the prominent lines in the visible spectra emitted from the sparks were observed. The possible mechanisms of light emission in spark afterglow were discussed, and some tentative estimations of excitation temperatures in the spark channels were made.

Measurements of Relative Intensities of Spectral Lines in the Emission from Hydrogen and Helium Spark Channels

Using discharge peak currents of about 200 kA measurements of voltage drop, expansion rates, etc. were made in spark channels in various gases, but principally in hydrogen, at atmospheric ...

J. D. Craggs

Papers

Cross Sections for Ionization of the Inert Gases by Electron Impact

Measurement of Reignition Voltage Characteristics for High Current Spark Gaps in Air

Measurements of Attachment Coefficients in Oxygen using an Electron Filter Technique

Measurements of Relative Intensities of Spectral Lines in the Emission from Hydrogen and Helium Spark Channels

Some Properties of High Current Spark Channels