Mechanical variation of plasma potential, electron temperature and plasma density

1992 ◽  
Vol 1 (2) ◽  
pp. 87-93 ◽  
Author(s):  
N Hershkowitz ◽  
Moo-Hyun Cho ◽  
J Pruski
Keyword(s):  
Electron Temperature ◽  
Plasma Density ◽  
Plasma Potential

Stability and spatial characterization of electron cyclotron resonance processing plasmas

1991 ◽  
Vol 69 (3-4) ◽  
pp. 195-201 ◽  
Author(s):  
P. K. Shufflebotham ◽  
D. J. Thomson
Keyword(s):  
Electron Temperature ◽  
Plasma Density ◽  
Cyclotron Resonance ◽  
Electron Cyclotron Resonance ◽  
Plasma Potential ◽  
Electron Cyclotron ◽  
Temperature Plasma ◽  
Ecr Plasma ◽  
The Stability ◽  
System Variables

This paper presents preliminary measurements of the spatial variation of the plasma density, electron temperature, plasma potential, and floating voltage within a divergent magnetic field electron cyclotron resonance (ECR) plasma processing reactor. The measurements are performed using an orbital-motion-limited cylindrical Langmuir probe designed specifically for use in these plasmas. A brief discussion of the stability and uniformity of divergent field plasmas in general, and qualitative techniques for the diagnosis of these properties, is also given. It was found that these plasmas generally occurred in distinct "modes," characterized by unique shapes and dependences on system variables, and between which discontinuous, noisy, and often bistable transitions occurred. Axially resolved probe measurements performed under ECR conditions showed that the plasma density exhibited a broadly peaked profile, while the electron temperature showed a sharp peak at ECR. The differences in these profiles leads to three qualitatively different plasma regions available for use in ECR processing. The variation of the plasma potential explains the origin of the axial ion beams that commonly occur in these systems.

Combined influence of axial electron temperature and exponential plasma density ramp on the self-focusing of a chirped laser in plasma

2020 ◽  
Vol 75 (7) ◽  
pp. 671-675
Author(s):  
Niti Kant ◽  
Vishal Thakur
Keyword(s):  
Electron Temperature ◽  
Pulse Laser ◽  
Plasma Density ◽  
Beam Width ◽  
Spot Size ◽  
Higher Order ◽  
The Self ◽  
Chirped Pulse ◽  
Self Focusing ◽  
Paraxial Ray

AbstractAn analysis of the self-focusing of highly intense chirped pulse laser under exponential plasma density ramp with higher order value of axial electron temperature has been done. Beam width parameter is derived by using paraxial ray approximation and then solved numerically. It is seen that self-focusing of chirped pulse laser is intensely affected by the higher order values of axial electron temperature. Further, influence of exponential plasma density ramp is studied and it is concluded that self-focusing of laser enhances and occurs earlier. On the other hand defocusing of beam reduces to the great extent. It is noticed that the laser spot size reduces significantly under joint influence of the density ramp and the axial electron temperature. Present analysis may be useful for the analysis of quantum dots, the laser induced fusion and etc.

The attachment length in orificed hollow cathodes

2021 ◽  
Author(s):  
Christopher Wordingham ◽  
Pierre-Yves Taunay ◽  
Edgar Choueiri
Keyword(s):  
Electron Temperature ◽  
Plasma Density ◽  
Hollow Cathode ◽  
Computational Models ◽  
Closed Form Solution ◽  
Form Solution ◽  
Decay Length ◽  
Plasma Density Profile ◽  
Wide Range ◽  
Approximate Boundary Condition

Abstract A first-principles approach to obtain the attachment length within a hollow cathode with a constrictive orifice, and its scaling with internal cathode pressure, is developed. This parameter, defined herein as the plasma density decay length scale upstream of (away from) the cathode orifice, is critical because it controls the utilization of the hollow cathode insert and influences cathode life. A two-dimensional framework is developed from the ambipolar diffusion equation for the insert-region plasma. A closed-form solution for the plasma density is obtained using standard partial differential equation techniques by applying an approximate boundary condition at the cathode orifice plane. This approach also yields the attachment length and electron temperature without reliance on measured plasma property data or complex computational models. The predicted plasma density profile is validated against measurements from the NSTAR discharge cathode, and calculated electron temperatures and attachment lengths agree with published values. Nondimensionalization of the governing equations reveals that the solution depends almost exclusively on the neutral pressure-diameter product in the insert plasma region. Evaluation of analytical results over a wide range of input parameters yields scaling relations for the variation of the attachment length and electron temperature with the pressure-diameter product. For the range of orifice-to-insert diameter ratio studied, the influence of orifice size is shown to be small except through its effect on insert pressure, and the attachment length is shown to be proportional to the insert inner radius, suggesting high-pressure cathodes should be constructed with larger-diameter inserts.

scholarly journals Effect of the gas puff location on the divertor plasma properties in COMPASS tokamak

2020 ◽  
Vol 1492 (1) ◽  
pp. 012003
Author(s):  
M Dimitrova ◽  
M Tomes ◽  
Tsv Popov ◽  
R Dejarnac ◽  
J Stockel ◽  
...  
Keyword(s):  
Electron Temperature ◽  
Vacuum Chamber ◽  
Plasma Potential ◽  
Saturation Current ◽  
Langmuir Probes ◽  
Plasma Parameters ◽  
Plasma Properties ◽  
Low Field ◽  
Saturation Current Density ◽  
Deuterium Gas

Abstract Langmuir probes are used to study the plasma parameters in the divertor during deuterium gas puff injection on the high- (HFS) or low-field sides (LFS). The probe data were processed to evaluate the plasma potential and the electron temperatures and densities. A difference was found in the plasma parameters depending on the gas puff location. In the case of a gas puff on the LFS, the plasma parameters changed vastly, mainly in the inner divertor – the plasma potential, the ion saturation-current density and the electron temperature dropped. After the gas puff, the electron temperature changed from 10-15 eV down to within the 5-9 eV range. As a result, the parallel heat-flux density decreased. At the same time, in the outer divertor the plasma parameters remained the same. We thus concluded that using a gas puff on the LFS will facilitate reaching a detachment regime by increasing the density of puffed neutrals. When the deuterium gas puff was on the HFS, the plasma parameters in the divertor region remained almost the same before and during the puff. The electron temperature decreased with just few eV as a result of the increased amount of gas in the vacuum chamber.

PICASSO: The Golden CubeSat

2021 ◽  
Author(s):  
Noel Baker ◽  
Michel Anciaux ◽  
Philippe Demoulin ◽  
Didier Fussen ◽  
Didier Pieroux ◽  
...  
Keyword(s):  
Electron Temperature ◽  
Plasma Density ◽  
Space Science ◽  
Lessons Learned ◽  
Vertical Profiles ◽  
Proof Of Concept ◽  
Scientific Instruments ◽  
The Earth ◽  
Spacecraft Potential

<p>Led by the Belgian Institute for Space Aeronomy, the ESA-backed mission PICASSO (PICo-Satellite for Atmospheric and Space Science Observations) successfully launched its gold-plated satellite on an Arianespace Vega rocket in September 2020. PICASSO is a 3U CubeSat mission in collaboration with VTT Technical Research Center of Finland Ltd, AAC Clyde Space Ltd. (UK), and the CSL (Centre Spatial de Liège), Belgium. The commissioning of the two onboard scientific instruments is currently ongoing; once they are operational, PICASSO will be capable of providing scientific measurements of the Earth’s atmosphere. VISION, proposed by BISA and developed by VTT, will retrieve vertical profiles of ozone and temperature by observing the Earth's atmospheric limb during orbital Sun occultation; and SLP, developed by BISA, will measure in situ plasma density and electron temperature together with the spacecraft potential.</p><p>Serving as a groundbreaking proof-of-concept, the PICASSO mission has taught valuable lessons about the advantages of CubeSat technology as well as its many complexities and challenges. These lessons learned, along with preliminary measurements from the two instruments, will be presented and discussed.</p>

Comparison of plasma-density and electron-temperature profiles during the auroral modelling campaign ARIES

1991 ◽  
Vol 69 (8-9) ◽  
pp. 950-958 ◽  
Author(s):  
Joëlle Margot ◽  
A. G. McNamara
Keyword(s):  
Electron Temperature ◽  
Plasma Density ◽  
High Energy ◽  
Primary Electron ◽  
Temperature Profiles ◽  
Height Distribution ◽  
Optical Intensity ◽  
High Energy Electron ◽  
E Region ◽  
Primary Electrons

Plasma-density and electron-temperature profiles were measured during the auroral modelling campaign ARIES. This campaign consisted of two rockets launched in the auroral E region under different geophysical conditions. The plasma-density and electron-temperature behaviours were tentatively related to the energy and intensity of the ionizing primary-electron fluxes. It is concluded that the plasma-density height distribution can be used to estimate the primary-electrons energy. The set of data presented is sufficiently complete to allow, when used together with other types of experiments such as the height distribution of the optical intensity and the high-energy electron spectra, the achievement of the objective of the ARIES multi-instrument campaign, i.e., refinement of the auroral model.

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