Transmission experiment for measuring total positron–atom collision cross sections in a curved, axial magnetic field

1977 ◽  
Vol 48 (7) ◽  
pp. 822-828 ◽  
Author(s):  
W. E. Kauppila ◽  
T. S. Stein ◽  
G. Jesion ◽  
M. S. Dababneh ◽  
V. Pol
Keyword(s):  
Magnetic Field ◽  
Cross Sections ◽  
Axial Magnetic Field ◽  
Transmission Experiment ◽  
Collision Cross Sections ◽  
Atom Collision

Zero-Field Level Crossing in the Helium Atom

1972 ◽  
Vol 50 (2) ◽  
pp. 116-118 ◽  
Author(s):  
C. W. T. Chien ◽  
R. E. Bardsley ◽  
F. W. Dalby
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Helium Atom ◽  
Cross Sections ◽  
Zero Field ◽  
Level Crossing ◽  
Field Level ◽  
Collision Cross Sections ◽  
The Magnetic Field

Zero-field level-crossing techniques have been used to measure some upper-state lifetimes of the helium atom. The half-widths of curves obtained by plotting the polarization against the magnetic field strength for the n1D–21D transitions yielded lifetimes of 2.03 × 10−8 s for the 31D state, 3.36 × 10−8 s for the 41D state, and 7.44 × 10−8 s for the 51D state. Collision cross sections for these 1D levels were also determined.

Zur Begrenzung der radial en Ausdehnung des Li chtbogenstromes durch ein axiales Magnetfeld. II. Skalengesetze und Vergleich mit Experimenten / On Limitation of the Radial Extent of the Arc Current by Means of an Axial Magnetic Field. II. Scaling Laws and Comparison with Experimental Results

1972 ◽  
Vol 27 (4) ◽  
pp. 652-670
Author(s):  
O. Klüber
Keyword(s):  
Magnetic Field ◽  
Cross Sections ◽  
Scaling Laws ◽  
Axial Magnetic Field ◽  
Angular Frequency ◽  
Model Calculations ◽  
Simple Geometry ◽  
Radial Extent ◽  
Arc Current ◽  
Field Lines

Abstract In an arc with superimposed axial magnetic field, radial current components cause a rotational motion of the plasma column and produce azimuthal Hall currents and hence electromotive forces such that the arc current is guided by the magnetic field lines. In the first part of this paper the steady-state plasma equations have been solved for a homogeneous plasma in simple geometry, allowance being made for finite viscosity. Here, scaling laws giving the radial extent of the arc current are obtained. In addition, electrodes with finite cross sections are treated. The results of model calculations agree well with experimental data. Generally, the model is applicable, if the angular frequency of the plasma is small compared with the ion gyration frequency.

Methods of Measuring Electron–Atom Collision Cross Sections with an Atom Trap

2002 ◽  
pp. 357-390 ◽  
Author(s):  
R.S. Schappe ◽  
M.L. Keeler ◽  
Todd A. Zimmerman ◽  
M. Larsen ◽  
Paul Feng ◽  
...  
Keyword(s):  
Cross Sections ◽  
Atom Trap ◽  
Electron Atom ◽  
Collision Cross Sections ◽  
Atom Collision
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