Four-electrode probe for plasma studies in the GOL-NB multiple-mirror trap

2021 ◽  
Vol 16 (11) ◽  
pp. T11006
Author(s):  
E.N. Sidorov ◽  
V.I. Batkin ◽  
A.V. Burdakov ◽  
I.A. Ivanov ◽  
K.N. Kuklin ◽  
...  
Keyword(s):  
Low Temperature ◽  
Electric Field ◽  
Electron Temperature ◽  
Plasma Density ◽  
Initial Phase ◽  
Radial Electric Field ◽  
Langmuir Probes ◽  
Simultaneous Measurements ◽  
Probe Measurements

Abstract A system of four-electrode Langmuir probes developed for the GOL-NB multiple-mirror trap is discussed. The system is used for studies of a low-temperature start plasma (1019–1020 m-3, 5 eV) that fills the device during the initial phase of the experiment. The probe allows simultaneous measurements of plasma density, electron temperature and radial electric field. The accuracy of the probe measurements is also discussed.

Plane Wave Interaction with an Inhomogeneous Warm Plasma Column

1971 ◽  
Vol 49 (20) ◽  
pp. 2578-2588 ◽  
Author(s):  
Kanwal J. Parbhakar ◽  
Brian C. Gregory
Keyword(s):  
Electric Field ◽  
Electron Temperature ◽  
Plasma Column ◽  
Cold Plasma ◽  
Plane Electromagnetic Wave ◽  
Wave Interaction ◽  
Radial Electric Field ◽  
Main Resonance ◽  
At Resonance ◽  
Warm Plasma

The interaction of a plane electromagnetic wave with an inhomogeneous warm plasma column is studied as a boundary value problem using a wave matching method. The plasma is characterized by a uniform electron temperature T and a parabolic density distribution N00 (1 − αr2/α2), where N00 is the central line density, α the inhomogeneity parameter, and a the column radius. The coupled Maxwell's and first two moment equations, assuming scalar pressure, are solved numerically without the quasi-static assumption. The resonances cannot be characterized by a single parameter; the effects of α, T, and N00 are studied separately. The resonances are located by noting that the magnitude of the scattering coefficient is unity (for a unit amplitude incident wave) at resonance. The maxima in the scattering are associated with the maxima in the coupling.It is found that the dielectric or the main resonance is a reasonably good radiator, while the plasma wave resonances (Tonks–Dattner resonances) are rather poor radiators. A detailed analysis of the radial electric field inside the plasma indicates that the main resonance is essentially a cold plasma resonance. As for the resonant frequencies, our results are in good agreement with those of Parker, Nickel, and Gould.The radial electric field at resonance inside the plasma is very sensitive to electron temperature.For the main resonance the field distribution at low electron temperature approaches that of a uniform cold plasma at resonance.

scholarly journals Параметры микроканальной структуры в начальной фазе искрового разряда в воздухе атмосферного давления в промежутке острие-плоскость

2021 ◽  
Vol 47 (2) ◽  
pp. 24
Author(s):  
К.И. Алмазова ◽  
А.А. Амирова ◽  
А.Н. Белоногов ◽  
В.В. Боровков ◽  
Г.Б. Рагимханов ◽  
...  
Keyword(s):  
Experimental Data ◽  
Electrical Conductivity ◽  
Electric Field ◽  
Electron Temperature ◽  
Electron Concentration ◽  
Initial Phase ◽  
Spark Discharge ◽  
Degree Of Ionization ◽  
Average Electron ◽  
High Degree

The results of investigations of the microstructure in the initial phase of a spark discharge in air in the 1.5 mm long gap between a tip and a plane are presented. Measurements show that, within 15 ns after breakdown, the channel is a set of a large number of microchannels, the current in the channel grows almost linearly up to 1 kA, and the electron concentration reaches the value of 2 • 10^19 cm^(−3). Kinetic processes in a separate microchannel were calculated based on the experimental data. It was found that the average electron temperature is in the range of 4-8 eV, the electric field is ~ 300 kV/cm, and the electrical conductivity is ∼10 Ω^(−1)•cm^(−1). The obtained results indicate that it is just the microstructure of the discharge determines the relatively high values of the average electron temperature in combination with a sufficiently high degree of ionization.

scholarly journals On nonlinear self-interaction of geodesic acoustic mode driven by energetic particles

2010 ◽  
Vol 77 (4) ◽  
pp. 457-467 ◽  
Author(s):  
G. Y. FU
Keyword(s):  
Electric Field ◽  
Plasma Density ◽  
Second Harmonic ◽  
Fluid Model ◽  
Density Perturbation ◽  
Radial Electric Field ◽  
Energetic Particles ◽  
Acoustic Mode ◽  
Second Order ◽  
Geodesic Acoustic Mode

AbstractIt is shown that nonlinear self-interaction of energetic particle-driven geodesic acoustic mode does not generate a second harmonic in radial electric field using the fluid model. However, kinetic effects of energetic particles can induce a second harmonic in the radial electric field. A formula for the second-order plasma density perturbation is derived. It is shown that a second harmonic of plasma density perturbation is generated by the convective nonlinearity of both thermal plasma and energetic particles. Near the midplane of a tokamak, the second-order plasma density perturbation (the sum of second harmonic and zero frequency sideband) is negative on the low field side with its size comparable to the main harmonic at low fluctuation level. These analytic predictions are consistent with the recent experimental observation in DIII-D.

Investigation of the Structure and the Plasma Parameters in a "Critical Velocity" Rotating Plasma

1976 ◽  
Vol 31 (8) ◽  
pp. 934-941 ◽  
Author(s):  
G. Himmel ◽  
E. Möbius ◽  
A. Piel
Keyword(s):  
Electron Temperature ◽  
Critical Velocity ◽  
Plasma Density ◽  
Detailed Balance ◽  
Current Transport ◽  
Langmuir Probes ◽  
Plasma Parameters ◽  
Electron Heating ◽  
First Time ◽  
Stream Instability

AbstractThe structure and the plasma parameters of a rotating plasma showing Alfvén's critical velocity were investigated for the first time by means of Langmuir probes. It was demonstrated that the occurrence of the critical velocity is causally connected with the formation of a spoke structure. The electron temperature and the plasma density were determined with local resolution by which a detailed balance concerning the plasma density and the current transport became possible. The importance of turbulent electron heating for rapid ionization at the critical velocity is emphasized. In this process the modified two-stream-instability obviously plays an outstanding role.

scholarly journals Investigation of turbulence rotation and radial electric field in the island divertor and plasma edge at W7-X

2019 ◽  
Vol 61 (5) ◽  
pp. 054003 ◽  
Author(s):  
A Krämer-Flecken ◽  
X Han ◽  
T Windisch ◽  
J Cosfeld ◽  
P Drews ◽  
...  
Keyword(s):  
Electric Field ◽  
Radial Electric Field ◽  
Plasma Edge
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