A sensitive microwave interferometer for plasma diagnostics

1969 ◽  
Vol 3 (3) ◽  
pp. 371-375 ◽  
Author(s):  
J. R. Wallington ◽  
J. D. E. Beynon
Keyword(s):  
Phase Shift ◽  
Electron Density ◽  
Plasma Diagnostics ◽  
Collision Frequency ◽  
Plasma Frequency ◽  
Electron Collision ◽  
Microwave Attenuation ◽  
Electron Collision Frequency ◽  
Broad Dimension

More accurate methods of measuring microwave attenuation and phase are constantly being sought, particularly for such applications as plasma diagnostics. The microwave bridge technique described here was developed for the study of a quiescent plasma having an electron density of 1015 to 1018 m−3 corresponding to a plasma frequency of 3 × 108 to 1010 Hz, and an electron collision frequency of 1010 to 1011 s−1. The plasma had a broad dimension of 0·3 m. For such a plasma a probing frequency of 10 GHz was considered to be the most suitable; at this frequency the attenuation α and phase shift δβ expected were 0·1 < α< 50 dB and 1° < δβ < 1000° respectively.

Effects of temperature and electron collision frequency on the elastic electron–ion collisions in a collisional plasma

2013 ◽  
Vol 79 (5) ◽  
pp. 553-558 ◽  
Author(s):  
YOUNG-DAE JUNG ◽  
WOO-PYO HONG
Keyword(s):  
Phase Shift ◽  
Temperature Effect ◽  
Cross Section ◽  
Collision Frequency ◽  
Electron Collision ◽  
Elastic Electron ◽  
Dynamic Temperature ◽  
Electron Collision Frequency ◽  
Dynamic Screening ◽  
Ion Collision

AbstractThe effects of dynamic temperature and electron–electron collisions on the elastic electron–ion collision are investigated in a collisional plasma. The second-order eikonal analysis and the velocity-dependent screening length are employed to derive the eikonal phase shift and eikonal cross section as functions of collision energy, electron collision frequency, Debye length, impact parameter, and thermal energy. It is interesting to find out that the electron–electron collision effect would be vanished; however, the dynamic temperature effect is included in the first-order approximation. We have found that the dynamic temperature effect strongly enhances the eikonal phase shift as well as the eikonal cross section for electron–ion collision since the dynamic screening increases the effective shielding distance. In addition, the detailed characteristic behavior of the dynamic screening function is also discussed.

scholarly journals Decay of the electron density and the electron collision frequency between successive discharges of a pulsed plasma jet in N2

2019 ◽  
Vol 28 (3) ◽  
pp. 035020 ◽  
Author(s):  
Marc van der Schans ◽  
Bart Platier ◽  
Peter Koelman ◽  
Ferdi van de Wetering ◽  
Jan van Dijk ◽  
...  
Keyword(s):  
Electron Density ◽  
Collision Frequency ◽  
Plasma Jet ◽  
Electron Collision ◽  
Pulsed Plasma ◽  
Electron Collision Frequency

Reflexion levels and coupling regions in a horizontally stratified ionosphere

1959 ◽  
Vol 252 (1004) ◽  
pp. 53-68 ◽  
Keyword(s):  
Collision Frequency ◽  
Plasma Frequency ◽  
Wave Theory ◽  
Electron Collision ◽  
Ray Theory ◽  
Radio Waves ◽  
Quartic Equation ◽  
Full Wave ◽  
Electron Collision Frequency ◽  
Full Solution

The propagation of radio waves through a horizontally stratified and slowly varying ionosphere is governed, in the case of oblique incidence, by a quartic equation (Booker 1938). Ray theory breaks down when two roots of this quartic are equal, for then coupling occurs between the characteristic waves, and full wave theory must be used. This paper is concerned with determining the conditions under which the two roots are equal; it is not concerned with the full wave theory. Values of the plasma frequency, and electron collision frequency, which lead to equal roots, are determined, and are exhibited in a set of curves. A full solution of the ‘Booker’ quartic is also given for a case of special interest. It is pointed out that the electric wave-field is unlikely to become very large in a slowly varying ionosphere, so that, if the ionosphere were irregular, scattering cannot be unduly enhanced by a plasma resonance.

Mikrowellenmessungen der Elektronendichte und -stoßfrequenz in elektromagnetisch erzeugten Stoßwellen

1966 ◽  
Vol 21 (12) ◽  
pp. 2040-2046
Author(s):  
W. Makios
Keyword(s):  
Shock Front ◽  
Electron Density ◽  
Electron Density Distribution ◽  
Discharge Plasma ◽  
Collision Frequency ◽  
Initial Pressure ◽  
Electron Collision ◽  
Microwave Measurements ◽  
Electron Collision Frequency ◽  
Microwave Transmission

Microwave measurements were made of the electron density and the electron collision frequency in the plasma between the shock front and the discharge plasma of electromagnetically produced shock waves. These investigations were carried out in argon and hydrogen at po=2 mm Hg initial pressure and velocities ranging from M=5 to M=20. At higher velocities the discharge plasma advances right into the shock front. A 4-mm-microwave transmission interferometer was used. A system of LECHER wires in the measuring arm of the interferometer provided a spatial resolution of approximately 1 to 2 mm and proved successful in measuring the electron density distribution between the shock front and the following discharge plasma. In the case of hydrogen the rise of the electron density in the shock front is caused by compression of the precursor electrons. In argon, on the other hand, most of the electrons are produced behind the shock front. A typical relaxation of the electron density towards equilibrium was measured. It was also possible to measure the electron collision frequency in argon as a function of time (and hence of the distance from the shock front).

The numerical solution of the differential equations governing the reflexion of long radio waves from the ionosphere. II

1955 ◽  
Vol 248 (939) ◽  
pp. 45-72 ◽  
Keyword(s):  
Magnetic Field ◽  
Differential Equations ◽  
Numerical Solution ◽  
Electron Density ◽  
Experimental Work ◽  
Collision Frequency ◽  
Electron Collision ◽  
Radio Waves ◽  
Method Of Calculation ◽  
Electron Collision Frequency

This paper presents a series of curves which are the results of some calculations of the reflecting properties of various models of the ionosphere for radio waves of frequency 16 kc/s. The method of calculation was described in a previous paper (Budden 1955). No attempt is made to deduce a model of the ionosphere capable of explaining all the observations, but the aim has been rather to establish some general principles which may indicate how future theoretical and experimental work should be planned. In most of the calculations it was assumed that the earth’s magnetic field is vertical and that the electron collision frequency in the ionosphere is constant. The limitations imposed by these restrictions are discussed. The first half of the paper describes some calculations for a model of the ionosphere in which the electron density increases exponentially with height, and the second half deals with a model having both D - and E -layers. The results in both cases are compared with observations.

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