Velocity of particles released by plasma stream erosion of surfaces; spectroscopic Doppler measurements

1978 ◽  
Vol 20 (4) ◽  
pp. 323-332 ◽  
Author(s):  
L Kristoferson
Keyword(s):  
Plasma Stream ◽  
Stream Erosion

Long-pulse plasma source for SMOLA helical mirror

2021 ◽  
Vol 87 (2) ◽  
Author(s):  
Ivan A. Ivanov ◽  
V. O. Ustyuzhanin ◽  
A. V. Sudnikov ◽  
A. Inzhevatkina
Keyword(s):  
Magnetic Field ◽  
Gas Flow ◽  
Supply Voltage ◽  
Hydrogen Plasma ◽  
Plasma Source ◽  
Lanthanum Hexaboride ◽  
Plasma Stream ◽  
Plasma Parameters ◽  
Plasma Properties ◽  
Plasma Gun

A plasma gun for forming a plasma stream in the open magnetic mirror trap with additional helicoidal field SMOLA is described. The plasma gun is an axisymmetric system with a planar circular hot cathode based on lanthanum hexaboride and a hollow copper anode. The two planar coils are located around the plasma source and create a magnetic field of up to 200 mT. The magnetic field forms the magnetron configuration of the discharge and provides a radial electric insulation. The source typically operates with a discharge current of up to 350 A in hydrogen. Plasma parameters in the SMOLA device are Ti ~ 5 eV, Te ~ 5–40 eV and ni ~ (0.1–1)  × 1019 m−3. Helium plasma can also be created. The plasma properties depend on the whole group of initial technical parameters: the cathode temperature, the feeding gas flow, the anode-cathode supply voltage and the magnitude of the cathode magnetic insulation.

Cerenkov and cyclotron instabilities in a plasma stream

1967 ◽  
Vol 1 (1) ◽  
pp. 1-27 ◽  
Author(s):  
C. F. Knox
Keyword(s):  
Magnetic Field ◽  
Plane Wave ◽  
Cold Plasma ◽  
Numerical Calculations ◽  
Graphical Form ◽  
Plasma Stream ◽  
Wave Growth ◽  
Stationary Medium ◽  
Phase Propagation ◽  
Positive Ion

The model of a stationary medium traversed by a weak plasma stream directed along a magnetic field is investigated. The usual linear treatment is adopted, and the stream is taken to be ‘cold’, with only electron (perturbation) motions considered. The objective is to assess the plane-wave growth associated with both Cerenkov and cyclotron instabilities; in particular, the dependence of the growth on frequency and angle of phase propagation. The main discussion is of the case when the stationary medium is a cold plasma in which both electron and positive ion motions are taken into account. Various expressions for the growth are derived, and numerical calculations are presented in graphical form.

FORESAIL-1 and ESTCube-2 Cubesat experiments of Coulomb drag propulsion

2021 ◽  
Author(s):  
Pekka Janhunen ◽  
Petri Toivanen ◽  
Jarmo Kivekäs ◽  
Matias Meskanen ◽  
Jouni Polkko
Keyword(s):  
Solar Wind ◽  
Orbital Motion ◽  
General Purpose ◽  
Low Earth Orbit ◽  
Voltage Source ◽  
Status Report ◽  
Plasma Stream ◽  
Low Thrust ◽  
Coulomb Drag ◽  
Positive Mode

<p>Coulomb drag propulsion taps momentum from a natural plasma stream to generate propellantless low-thrust propulsion for a spacecraft. The plasma is attached to by means of a long, thin, charged metallic tether. The tether's electrostatic field deflects the motion of streaming plasma ions and transfers momentum from them. The technique can be applied in the solar wind (i.e., outside Earth's magnetosphere) to produce general-purpose interplanetar propulsion. This application is called the electric solar wind sail (E-sail). It can also be applied in low Earth orbit (LEO) to brake the satellite's orbital motion. Here the relevant plasma stream is the ram flow of the ionosphere due to the satellite's orbital motion. This application is called the plasma brake and it is useful for satellite deorbiting for mitigating the growing problem of orbital debris.</p> <p>Here we report on progress of two CubeSat missions (FORESAIL-1 and ESTCube-2) that are under construction for measuring the Coulomb drag effect in LEO.  Both are scheduled to fly in 2022. Both satellites deploy up to 300 m long tether, charge it up by a high-voltage source and measure the resulting Coulomb drag. The satellites are slowly spinning and the tether is tightened by the centrifugal force. The tether is deployed from a reel which is rotated slowly by an electric motor.  Both satellites use negative tether polarity, which is the case relevant for the plasma brake. ESTCube-2 contains, in addition, a positive mode experiment which is relevant for the E-sail. The plasma environment in LEO differs from the solar wind, so the measured positive mode Coulomb drag must be scaled to yield a prediction of the strength of the E-sail effect in the solar wind.</p> <p>The Coulomb drag is measured by two independent methods. In the first method we set the tether voltage on and off in sync with the satellite's rotation and thereby accumulate a change of the system's angular momentum. The Coulomb drag is inferred from the measured change of the spin rate per time unit. In the second method we estimate Coulomb drag from the speeded-up lowering of the satelllite's orbital altitude.</p> <p>The presentation is a status report of the technical progress of these two Coulomb drag CubeSat missions; FORESAIL-1 and ESTCube-2.</p>

Physical and Chemical Processes Research of Isotope Separation in Plasma under Magnetic Field

2014 ◽  
Vol 880 ◽  
pp. 128-133 ◽  
Author(s):  
Vyacheslav F. Myshkin ◽  
Dmitry A. Izhoykin ◽  
Ivan A. Ushakov ◽  
Viktor F. Shvetsov
Keyword(s):  
Magnetic Field ◽  
Carbon Dioxide ◽  
Plasma Flow ◽  
High Frequency ◽  
Isotope Separation ◽  
Carbon Dioxide Concentration ◽  
Plasma Stream ◽  
Reaction Products ◽  
Valence Electrons ◽  
Field Lines

It is known that chemical bonding is only possible when particles with antiparallel valence electrons spins orientation collide [1, 2]. In an external magnetic field unpaired electrons spins precession around the field lines is observed. Precession frequencies of valence electrons of magnetic and nonmagnetic nuclei differ, resulting in a different probability to collide in reactive state for different isotopes. The investigations results of magnetic field influence on the carbon isotopes redistribution between carbon dioxide and disperse carbon in plasmachemical processes are given. Argon-oxygen plasma by a high-frequency generator was produced. Carbon placed into reaction zone by the high-frequency electrode evaporation. The plasmachemical reaction products quenching in the plasma flow at the sampler probe were examined. It is found that the Laval nozzle sampler is more efficient for plasma stream cooling versus the cylindrical sampler. The effects of flow rate, pressure and carbon dioxide concentration on the plasma flow cooling efficiency were estimated.

Continuous prediction of clay-bed stream erosion in response to climate model output for a small urban watershed

2018 ◽  
Vol 32 (8) ◽  
pp. 1104-1119 ◽  
Author(s):  
Colin P. Brennan ◽  
Parna Parsapour-Moghaddam ◽  
Colin D. Rennie ◽  
Ousmane Seidou
Keyword(s):  
Climate Model ◽  
Model Output ◽  
Urban Watershed ◽  
Climate Model Output ◽  
Stream Erosion

scholarly journals PARAMETERS OF HYDROGEN PLASMA STREAMS IN QSPA-M AND THEIR DEPENDENCE ON EXTERNAL MAGNETIC FIELD

2021 ◽  
pp. 61-64
Author(s):  
M.S. Ladygina ◽  
Yu.V. Petrov ◽  
D.V. Yeliseev ◽  
V.A. Makhlai ◽  
N.V. Kulik ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electron Density ◽  
Hydrogen Plasma ◽  
Experimental Studies ◽  
Optical Emission ◽  
Plasma Electron ◽  
Plasma Stream ◽  
Visible Radiation ◽  
Order Of Magnitude ◽  
Plasma Electron Density

Present experimental studies are aimed at analysis of hydrogen plasma stream parameters in various working regimes of QSPA-M operation. Temporal distributions of plasma electron density are reconstructed with optical emission spectroscopy. The magnetic field influence on plasma streams parameters is analyzed. It is shown that in regimes with additional magnetic field the plasma electron density increases by an order of magnitude in comparison with a density value without magnetic field. The plasma velocity and energy density parameters as well as their temporal behaviors were estimatedin different operating regimes of QSPA-M facility. Features of plasma visible radiation were analyzed. This information is important for QSPA-M applications in experiments on interaction of powerful plasma streams with material surfaces.

scholarly journals High-Speed Monitoring of Dust Particles in ITER ELMs Simulation Experiments with QSPA Kh-50

10.14311/1759 ◽  
2013 ◽  
Vol 53 (2) ◽  
Author(s):  
Vadym A. Makhlaj ◽  
Igor E. Garkusha ◽  
Nikolay N. Aksenov ◽  
Alexander A. Chuvilo ◽  
Igor S. Landman
Keyword(s):  
Heat Load ◽  
High Speed ◽  
Plasma Accelerator ◽  
Dust Particles ◽  
Plasma Stream ◽  
Maximal Velocity ◽  
Start Time ◽  
Simulation Experiments ◽  
Dust Generation ◽  
Load Average

Dust generation under powerful plasma stream impacts has been studied in ITER ELM simulation experiments with QSPA Kh-50 plasma accelerator. Repetitive plasma exposures of tungsten have been performed by 0.25 ms plasma pulses and the heat load varied in the range (0.1÷1.1) MJm-2. Main characteristics of dust particles such as a number of ejected particles, their velocity, angular distribution and start time from the surface are investigated. Dust particles have not been observed under heat load below the cracking threshold. Quantity of dust particles rises with increasing heat load. Average velocities of dust particles are found to be strongly dependent on their start time from the surface after beginning of plasma-surface interaction. Maximal velocity achieved a few tens of meters per second.

scholarly journals Studies of plasma interactions with tungsten targets in PF-1000U facility

Nukleonika ◽  
2016 ◽  
Vol 61 (2) ◽  
pp. 149-153
Author(s):  
Maryna S. Ladygina ◽  
Elzbieta Skladnik-Sadowska ◽  
Dobromil R. Zaloga ◽  
Marek J. Sadowski ◽  
Monika Kubkowska ◽  
...  
Keyword(s):  
Experimental Studies ◽  
Optical Emission ◽  
Target Surface ◽  
Sample Surface ◽  
Optical Microscope ◽  
High Plasma ◽  
Spectral Lines ◽  
Optical Measurements ◽  
Plasma Stream ◽  
Plasma Parameters

Abstract This paper presents results of experimental studies of tungsten samples of 99.95% purity, which were irradiated by intense plasma-ion streams. The behaviour of tungsten, and particularly its structural change induced by high plasma loads, is of great importance for fusion technology. The reported measurements were performed within a modified PF-1000U plasma-focus facility operated at the IFPiLM in Warsaw, Poland. The working gas was pure deuterium. In order to determine the main plasma parameters and to study the behaviour of impurities at different instants of the plasma discharge, the optical emission spectroscopy was used. The dependence of plasma parameters on the initial charging voltage (16, 19 and 21 kV) was studied. Detailed optical measurements were performed during interactions of a plasma stream with the tungsten samples placed at the z-axis of the facility, at a distance of 6 cm from the electrode outlets. The recorded spectra showed distinct WI and WII spectral lines. Investigation of a target surface morphology, after its irradiation by intense plasma streams, was performed by means of an optical microscope. The observations revealed that some amounts of the electrodes material (mainly copper) were deposited upon the irradiated sample surface. In all the cases, melted zones were observed upon the irradiated target surface, and in experiments performed at the highest charging voltage there were formed some cracks.

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