scholarly journals The Momentum Transfer Cross Section for Electrons in Helium

1967 ◽  
Vol 20 (4) ◽  
pp. 369 ◽  
Author(s):  
RW Crompton ◽  
MT Elford ◽  
RL Jory
Keyword(s):  
Energy Range ◽  
Momentum Transfer ◽  
Cross Section ◽  
Drift Velocity ◽  
Low Energy ◽  
Theoretical Cross Section ◽  
Velocity Data ◽  
The Cross ◽  
Energy Dependent ◽  
Momentum Transfer Cross Section

Measurements of the drift velocity, the ratio of diffusion coefficient to mobility, and the "magnetic drift velocity" for electrons in helium have been made at 293�K in the range 1.8 X 10−19 E/N −17 V cm2. From an analysis of the drift velocity data, an energy-dependent momentum transfer cross section has been derived for which an error of less than � 2 % is claimed over the central portion of the energy range. The cross section agrees with the theoretical cross section of La Bahn and Callaway to within 2% over the whole energy range. The agreement with the cross section derived by a number of procedures from the total elastic scattering cross section measured by Golden and Bandel is less satisfactory. The drift data are sufficiently accurate to enable a search to be made for the effects of fine structure in the cross section at low energy. The results do not support the existence of such structure.

scholarly journals Momentum Transfer Cross Section for Electrons in Krypton Derived from Measurements of the Drift Velocity in H2?Kr Mixtures

1988 ◽  
Vol 41 (5) ◽  
pp. 701 ◽  
Author(s):  
JP England ◽  
MT Elford
Keyword(s):  
Momentum Transfer ◽  
Cross Section ◽  
Drift Velocity ◽  
Cross Sections ◽  
Personal Communication ◽  
Electron Drift ◽  
Velocity Data ◽  
The Cross ◽  
Momentum Transfer Cross Section ◽  
Made In

Measurements of electron drift velocities have been made in 0�4673% and 1�686% hydrogenkrypton mixtures at 293 K and values of E/ N from 0�08 to 2�5 Td with an estimated uncertainty of <�0�7%. The data have been used in conjunction with the H2 cross sections of England et aL (1988) to derive the momentum transfer cross section for krypton over the energy range 0�05 to 6�0 eV. The drift velocity data have also been used to test the Kr momentum transfer cross sections of Koizumi et aL (1986) and Hunter (personal communication 1988). The cross section of Koizumi et aL is clearly incompatible with the present measurements while the cross section of Hunter has been used to predict these measurements to within 1% to 3%.

scholarly journals The Momentum Transfer Cross Section for Electrons in Mercury Vapour from 0·1 to 5 eV

1980 ◽  
Vol 33 (2) ◽  
pp. 259 ◽  
Author(s):  
MT Elford
Keyword(s):  
Experimental Data ◽  
Energy Range ◽  
Momentum Transfer ◽  
Cross Section ◽  
Drift Velocity ◽  
Cross Sections ◽  
Mercury Vapour ◽  
Velocity Data ◽  
Maximum Value ◽  
Momentum Transfer Cross Section

The momentum transfer cross section for electrons in mercury vapour has been derived over the energy range 0�1-5 eV from the drift velocity data of Elford (1980). The cross section has a resonance at 0�5 eV with a maximum value of 180 A 2 (1� 8 x 10-18 m2). It is shown that previous cross sections derived either from experimental data or obtained by ab initio calculations are incompatible with the drift velocity data.

scholarly journals Momentum Transfer Cross Section for e??Kr Scattering

1993 ◽  
Vol 46 (2) ◽  
pp. 249 ◽  
Author(s):  
MJ Brennan ◽  
KF Ness
Keyword(s):  
Energy Range ◽  
Momentum Transfer ◽  
Cross Section ◽  
Drift Velocity ◽  
Cross Sections ◽  
Theoretical Calculations ◽  
Transport Coefficients ◽  
Velocity Data ◽  
Experimental Errors ◽  
Momentum Transfer Cross Section

The momentum transfer cross section for electrons in krypton has been derived over the energy range Q-4 eV from an analysis of drift velocity and DT/I-' data for hydrogen-krypton mixtures. At energies in the vicinity of the Ramsauer-Townsend minimum, the present work differs significantly from derivations based on analyses of drift velocity data alone. The overall uncertainty in the derived cross section reflects the experimental errors in the transport coefficients, the uncertainty in the cross sections used to represent the hydrogen component in the mixtures, and the uncertainty associated with the X2 minimisation. The present cross section is compared with recent theoretical calculations and other experimental derivations.

Momentum transfer cross section of argon deduced from electron drift velocity data

1990 ◽  
Vol 23 (7) ◽  
pp. 842-850 ◽  
Author(s):  
M Suzuki ◽  
T Taniguchi ◽  
H Tagashira
Keyword(s):  
Momentum Transfer ◽  
Cross Section ◽  
Drift Velocity ◽  
Electron Drift Velocity ◽  
Electron Drift ◽  
Velocity Data ◽  
Momentum Transfer Cross Section

Momentum transfer cross section of xenon deducted from electron drift velocity data

1992 ◽  
Vol 25 (1) ◽  
pp. 50-56 ◽  
Author(s):  
M Suzuki ◽  
T Taniguchi ◽  
N Yoshimura ◽  
H Tagashira
Keyword(s):  
Momentum Transfer ◽  
Cross Section ◽  
Drift Velocity ◽  
Electron Drift Velocity ◽  
Electron Drift ◽  
Velocity Data ◽  
Momentum Transfer Cross Section

scholarly journals The Momentum Transfer Cross Section for Electrons in Helium Derived from Drift Velocities at 77°K

1970 ◽  
Vol 23 (5) ◽  
pp. 667 ◽  
Author(s):  
RW Crompton ◽  
MT Elford ◽  
AG Robertson
Keyword(s):  
Energy Range ◽  
Momentum Transfer ◽  
Cross Section ◽  
Scattering Length ◽  
Direct Determination ◽  
A Value ◽  
Energy Dependent ◽  
Momentum Transfer Cross Section

Drift velocities of electrons in helium at 76.8�K have been measured for 8 X lO−20 ≤ E/N ≤ 2 X lO−17 V cm2. From these data, and the earlier measurements of Crompton, Elford, and Jory made at 293�K, the energy-dependent momentum transfer cross section has been determined for electrons with energies between 0.008 and 6 eV. The present cross section agrees with that of Crompton, Elford, and Jory to within 1 %. The extension of the energy range to 8 meV permits a direct determination of the scattering length, for which a value of 1.19 ao is obtained.

scholarly journals The Momentum Transfer Cross Section for Krypton

1990 ◽  
Vol 43 (1) ◽  
pp. 19 ◽  
Author(s):  
Jim Mitroy
Keyword(s):  
Momentum Transfer ◽  
Cross Section ◽  
Drift Velocity ◽  
Molecular Hydrogen ◽  
Effective Range ◽  
Velocity Data ◽  
Range Theory ◽  
Effective Range Theory ◽  
Momentum Transfer Cross Section

A form of modified effective range theory (MERT) has been used to analyse drift velocity data for both pure krypton and molecular hydrogen-krypton mixtures. The present momentum transfer cross section reproduces the data to within 4% for pure krypton and to within 1 �0% for the H2-Kr mixtures.

Momentum transfer cross section of krypton deduced from electron drift velocity data

1989 ◽  
Vol 22 (12) ◽  
pp. 1848-1855 ◽  
Author(s):  
M Suzuki ◽  
T Taniguchi ◽  
H Tagashira
Keyword(s):  
Momentum Transfer ◽  
Cross Section ◽  
Drift Velocity ◽  
Electron Drift Velocity ◽  
Electron Drift ◽  
Velocity Data ◽  
Momentum Transfer Cross Section

scholarly journals The Cross Section for the J = 0 → 2 Rotational Excitation of Hydrogen by Slow Electrons

1969 ◽  
Vol 22 (6) ◽  
pp. 715 ◽  
Author(s):  
RW Crompton ◽  
DK Gibson ◽  
AI McIntosh
Keyword(s):  
Momentum Transfer ◽  
Cross Section ◽  
Cross Sections ◽  
Vibrational Excitation ◽  
The Cross ◽  
Excitation Processes ◽  
Slow Electrons ◽  
And Diffusion ◽  
Momentum Transfer Cross Section ◽  
Section Analysis

The results of electron drift and diffusion measurements in parahydrogen have been analysed to determine the cross sections for momentum transfer and for rotational and vibrational excitation. The limited number of possible excitation processes in parahydrogen and the wide separation of the thresholds for these processes make it possible to determine uniquely the J = 0 → 2 rotational cross section from threshold to 0.3 eV. In addition, the momentum transfer cross section has been determined for energies less than 2 eV and it is shown that, near threshold, a vibrational cross section compatible with the data must lie within relatively narrow limits. The problems of uniqueness and accuracy inherent in the swarm method of cross section analysis are discussed. The present results are compared with other recent theoretical and experimental determinations; the agreement with the most recent calculations of Henry and Lane is excellent.

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