Experimental Investigations of Discharge Characteristics and Plasma Parameters of a Cylindrical Cathode Discharge in a Magnetic Field I Discharge Characteristics

1984 ◽  
Vol 24 (3) ◽  
pp. 225-235 ◽  
Author(s):  
G. Pavelescu ◽  
M. Bâlâceanu ◽  
C. Popovici
Keyword(s):  
Magnetic Field ◽  
Experimental Investigations ◽  
Plasma Parameters ◽  
Discharge Characteristics

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.

Experimental investigations on finishing of a brass specimen by magneto-rheological honing technique

2021 ◽  
pp. 251659842110157
Author(s):  
Chinu Kumari ◽  
Sanjay Kumar Chak
Keyword(s):  
Magnetic Field ◽  
Process Parameters ◽  
Surface Finish ◽  
Rotational Speed ◽  
Field Application ◽  
Surface Finishing ◽  
Experimental Investigations ◽  
Significant Parameter ◽  
Magnetizing Current ◽  
Magneto Rheological

Magneto-rheological abrasive honing (MRAH) is an unconventional surface finishing technique that relies on abrasives mixed with a unique finishing fluid, which changes its characteristics on magnetic field application. This process imparts nanometric-level surface finish with a significant amount of uniformity. Rotating motion of the workpiece and continuous reciprocation of the finishing fluid in the MRAH process are recognized as the major aspects for adopting this process in finishing non-magnetic materials. The finishing obtained through the MRAH process relies on the workpiece’s material properties and process parameters such as concentration of abrasives in finishing fluid, rotational speed of the workpiece, and magnetic field strength/magnetizing current. To study the efficacy of MRAH process, a parametric study was conducted by performing few experiments on a brass workpiece. Design of experiment approach was adopted to plan the experiments, and the effect of different values of magnetizing current, the concentration of abrasives, and rotational speed on the surface finish were analyzed through the application of analysis of variance (ANOVA). From ANOVA, the rotational speed was found as the most significant parameter with a contribution of 48.90% on % reduction in roughness value (%∇Ra). Around 57% of roughness reduction was obtained at the optimized value of process parameters.

scholarly journals What Density of Magnetosheath Sodium Ions Can Provide the Observed Decrease in the Magnetic Field of the “Double Magnetopause” during the First MESSENGER Flyby?

Symmetry ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1168
Author(s):  
Elena Belenkaya ◽  
Ivan Pensionerov
Keyword(s):  
Magnetic Field ◽  
Analytical Approach ◽  
Field Structure ◽  
Sodium Ions ◽  
Plasma Parameters ◽  
Calculation Results ◽  
Magnetizing Current ◽  
The Magnetic Field ◽  
Density Excess

On 14 January 2008, the MESSENGER spacecraft, during its first flyby around Mercury, recorded the magnetic field structure, which was later called the “double magnetopause”. The role of sodium ions penetrating into the Hermean magnetosphere from the magnetosheath in generation of this structure has been discussed since then. The violation of the symmetry of the plasma parameters at the magnetopause is the cause of the magnetizing current generation. Here, we consider whether the change in the density of sodium ions on both sides of the Hermean magnetopause could be the cause of a wide diamagnetic current in the magnetosphere at its dawn-side boundary observed during the first MESSENGER flyby. In the present paper, we propose an analytical approach that made it possible to determine the magnetosheath Na+ density excess providing the best agreement between the calculation results and the observed magnetic field in the double magnetopause.

HelioSwarm: The Nature of Turbulence in Space Plasmas

2021 ◽  
Author(s):  
Harlan Spence ◽  
Kristopher Klein ◽  
HelioSwarm Science Team
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Large Scale ◽  
Solar Wind Plasma ◽  
Turbulent Energy ◽  
Space Plasmas ◽  
Plasma Parameters ◽  
Astrophysical Plasmas ◽  
Ion Distributions ◽  
Background Magnetic Field

<p>Recently selected for phase A study for NASA’s Heliophysics MidEx Announcement of Opportunity, the HelioSwarm Observatory proposes to transform our understanding of the physics of turbulence in space and astrophysical plasmas by deploying nine spacecraft to measure the local plasma and magnetic field conditions at many points, with separations between the spacecraft spanning MHD and ion scales.  HelioSwarm resolves the transfer and dissipation of turbulent energy in weakly-collisional magnetized plasmas with a novel configuration of spacecraft in the solar wind. These simultaneous multi-point, multi-scale measurements of space plasmas allow us to reach closure on two science goals comprised of six science objectives: (1) reveal how turbulent energy is transferred in the most probable, undisturbed solar wind plasma and distributed as a function of scale and time; (2) reveal how this turbulent cascade of energy varies with the background magnetic field and plasma parameters in more extreme solar wind environments; (3) quantify the transfer of turbulent energy between fields, flows, and ion heat; (4) identify thermodynamic impacts of intermittent structures on ion distributions; (5) determine how solar wind turbulence affects and is affected by large-scale solar wind structures; and (6) determine how strongly driven turbulence differs from that in the undisturbed solar wind. </p>

Resistive MHD modes in hollow cathodes external plasma

2021 ◽  
Author(s):  
Giulia Becatti ◽  
Francesco Burgalassi ◽  
Fabrizio Paganucci ◽  
Matteo Zuin ◽  
Dan M Goebel
Keyword(s):  
Magnetic Field ◽  
Hollow Cathode ◽  
Electric Propulsion ◽  
Axial Magnetic Field ◽  
Mhd Equations ◽  
Linear Perturbation ◽  
Plasma Parameters ◽  
Hollow Cathodes ◽  
Plume Region ◽  
Helical Mode

Abstract A significant number of plasma instabilities occur in the region just outside of hollow cathodes, depending on the injected gas flow, the current level and the application of an external magnetic field. In particular, the presence of an axial magnetic field induces a helical mode, affecting all the plasma parameters and the total current transported by the plasma. To explore the onset and behavior of this helical mode, the fluctuations in the plasma parameters in the current-carrying plume outside of a hollow cathode discharge have been investigated. The hollow cathode was operated at a current of 25 A, and at variable levels of propellant flow rate and applied magnetic fields. Electromagnetic probes were used to measure the electromagnetic fluctuations, and correlation analysis between each of the probe signals provided spatial-temporal characterization of the generated waves. Time-averaged plasma parameters, such as plasma potential and ion energy distribution function, were also collected in the near-cathode plume region by means of scanning emissive probe and retarding potential analyzer. The results show that the helical mode exists in the cathode plume at sufficiently high applied magnetic field, and is characterized by the presence of a finite electromagnetic component in the axial direction, detectable at discharge currents $\geq$ 25 A. A theoretical analysis of this mode reveals that one possible explanation is consistent with the hypotheses of resistive magnetohydrodynamics, which predicts the presence of helical modes in the forms of resistive kink. The analysis has been carried out by linear perturbation of the resistive MHD equations, from which it is possible to obtain the dispersion relation of the mode and find the $k-\omega$ unstable branch associated with the instability. These findings provided the basis for more detailed investigation of resistive MHD modes and their effect in the plume of hollow cathodes developed for electric propulsion application.

scholarly journals Experimental and numerical investigation of plasma parameters in the magnetosheath

2018 ◽  
Vol 145 ◽  
pp. 03003
Author(s):  
Polya Dobreva ◽  
Monio Kartalev ◽  
Olga Nitcheva ◽  
Natalia Borodkova ◽  
Georgy Zastenker
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Numerical Investigation ◽  
Euler Equations ◽  
Ideal Gas ◽  
Bow Shock ◽  
Plasma Parameters ◽  
Wind Spacecraft ◽  
The Magnetic Field ◽  
Good Agreement

We investigate the behaviour of the plasma parameters in the magnetosheath in a case when Interball-1 satellite stayed in the magnetosheath, crossing the tail magnetopause. In our analysis we apply the numerical magnetosheath-magnetosphere model as a theoretical tool. The bow shock and the magnetopause are self-consistently determined in the process of the solution. The flow in the magnetosheath is governed by the Euler equations of compressible ideal gas. The magnetic field in the magnetosphere is calculated by a variant of the Tsyganenko model, modified to account for an asymmetric magnetopause. Also, the magnetopause currents in Tsyganenko model are replaced by numericaly calulated ones. Measurements from WIND spacecraft are used as a solar wind monitor. The results demonstrate a good agreement between the model-calculated and measured values of the parameters under investigation.

Corrosion Phenomena of Eurofeer Steel in Pb-17Li Stationary Flow at Magnetic Field

2006 ◽  
Author(s):  
E. Platacis ◽  
I. Bucenieks ◽  
F. Muktupavel ◽  
A. Shishko
Keyword(s):  
Magnetic Field ◽  
Structural Material ◽  
Corrosion Rate ◽  
Liquid Metals ◽  
Metal Flow ◽  
Stationary Flow ◽  
Operating Conditions ◽  
Experimental Investigations ◽  
Martensitic Steels ◽  
Eurofer 97

Search of new energy sources draws the increasing attention to use for this purpose of reactors. In the Europe some years the program EUROATOM uniting scientific of the many countries for the decision of constructive problems at designing of fusion reactors operates. One of the main things in this program is the problem of liquid metals breeder blanket behaviour. Structural material of blanket should meet high requirements because of extreme operating conditions. Therefore the knowledge of the effect of metals flow velocity, temperatures and also a neutron irradiation and a magnetic field on the corrosion processes are necessary. At the moment the eutectic lead -lithium (Pb-17Li) is considered as the most suitable tritium breeder material [1–3]. In turn as a structural material have been tested both many austenitic and ferritic-martensitic steels [2–4]. As the optimum variant is considered steel EUROFER 97, which corrosion rate in liquid Pb-17Li eutectic is the least [3,4]. However, these results have been received without taking into account influence of a strong magnetic field. At the same time, this influence should be essential, as because of change of hydrodynamics of a liquid metal flow, and because of interaction of a magnetic field with a ferromagnetic steel. It has been shown in [5,6] that the magnetic field leads to increase of corrosion rate for austenitic (316L) and martensitic (1,4914) steels. Experimental data for EUROFER 97, and also a theoretical substantiation of the phenomenon are absent, that creates essential difficulties for forecasting working capacity of blanket construction. The aim of presented work were the theoretical and experimental investigations of magnetic field influence on the corrosion of EUROFER 97 steel exposed to flowing Pb-17 Li in specific designed loop.

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