scholarly journals Integrated study on the comprehensive magnetic-field configuration performance in the 150 kW superconducting magnetoplasmadynamic thruster

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jinxing Zheng ◽  
Haiyang Liu ◽  
Yuntao Song ◽  
Cheng Zhou ◽  
Yong Li ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Specific Impulse ◽  
Superconducting Magnet ◽  
High Energy ◽  
Field Configuration ◽  
Particle Simulation ◽  
Acceleration Process ◽  
Pic Method ◽  
Integrated Study ◽  
Maximum Thrust

AbstractHigher magnetic fields are always favoured in the magnetoplasmadynamic thruster (MPDT) due to its superior control of the plasma profile and acceleration process. This paper introduces the world's first integrated study on the 150 kW level AF-MPDT equipped with a superconductive coil. A completely new way of using superconducting magnet technology to confine plasma with high energy and extremely high temperatures is proposed. Using the PIC method of microscopic particle simulation, the plasma magnetic nozzle effect and performance of the MPDT under different magnetic-field conditions were studied. The integrated experiment used demonstrated that, in conjunction with the superconducting coil, greater homogeneity and a stronger magnetic field not only caused more even cathode ablation and improved its lifespan but also improved the performance of the MPDT (maximum thrust was 4 N at 150 kW, 0.56 T). Maximum thrust efficiency reached 76.6% and the specific impulse reached 5714 s.

scholarly journals Generation of focusing ion beams by magnetized electron sheath acceleration

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
K. Weichman ◽  
J. J. Santos ◽  
S. Fujioka ◽  
T. Toncian ◽  
A. V. Arefiev
Keyword(s):  
Magnetic Field ◽  
High Energy ◽  
Ion Source ◽  
High Energy Density ◽  
Ion Acceleration ◽  
Acceleration Process ◽  
Hot Electron ◽  
Magnetic Field Effects ◽  
Multiple Species ◽  
2D And 3D

Abstract We present the first 3D fully kinetic simulations of laser driven sheath-based ion acceleration with a kilotesla-level applied magnetic field. The application of a strong magnetic field significantly and beneficially alters sheath based ion acceleration and creates two distinct stages in the acceleration process associated with the time-evolving magnetization of the hot electron sheath. The first stage delivers dramatically enhanced acceleration, and the second reverses the typical outward-directed topology of the sheath electric field into a focusing configuration. The net result is a focusing, magnetic field-directed ion source of multiple species with strongly enhanced energy and number. The predicted improvements in ion source characteristics are desirable for applications and suggest a route to experimentally confirm magnetization-related effects in the high energy density regime. We additionally perform a comparison between 2D and 3D simulation geometry, on which basis we predict the feasibility of observing magnetic field effects under experimentally relevant conditions.

scholarly journals RADIATION HAZARD ON EARTH AND IN NEAR-EARTH SPACE DURING MAGNETIC FIELD INVERSION

2019 ◽  
Vol 47 (1) ◽  
pp. 129-131
Author(s):  
O.O. Tsareva ◽  
V.Yu. Popov ◽  
H.V. Malova ◽  
E.P. Popova ◽  
M.V. Podzolko ◽  
...  
Keyword(s):  
Magnetic Field ◽  
High Energy ◽  
Field Configuration ◽  
Radiation Hazard ◽  
Dynamo Model ◽  
Earth Space ◽  
Near Earth Space ◽  
The Earth ◽  
The Magnetic Field ◽  
Field Inversion

Recent observations, such as the magnetic field strength decrease, a magnetic poles shifts and the South Atlantic anomaly increase, may indicate the beginning of the Earth’s magnetic field inversion. According to the geomagnetic dynamo model, the dipole component of the magnetic field is zeroed at the inversion time, and the quadrupole one becomes dominant. To assess the occurrence of radiation hazards on the Earth’s surface and in near-Earth space at the time of magnetic field inversion, a numerical model was developed that made it possible to compare the GCR and SCR fluxes (at minima and maxima of solar activity) penetrating the Earth (taking into account the atmosphere) and the ISS in periods of the dipole and quadrupole fields dominance. It was found that during the period of inversion the flow of GCR (high-energy particles) can increase no more than three times over the entire surface of the Earth and the radiation dose will not exceed permissible one for man. Also, a change of the magnetic field configuration will redistribute areas of increased radiation on the Earth’s surface (today these are the poles of the Earth), which can adversely affect people’s health in these areas.

scholarly journals Acceleration and escape processes of high-energy particles in turbulence inside hot accretion flows

2019 ◽  
Vol 485 (1) ◽  
pp. 163-178 ◽  
Author(s):  
Shigeo S Kimura ◽  
Kengo Tomida ◽  
Kohta Murase
Keyword(s):  
Dominant Role ◽  
High Energy ◽  
Field Configuration ◽  
Particle Energy ◽  
Acceleration Process ◽  
Accretion Flows ◽  
Bulk Motion ◽  
Normal Diffusion ◽  
Magnetohydrodynamic Simulations ◽  
High Energy Particles

Abstract We investigate acceleration and propagation processes of high-energy particles inside hot accretion flows. The magnetorotational instability (MRI) creates turbulence inside accretion flows, which triggers magnetic reconnection and may produce non-thermal particles. They can be further accelerated stochastically by the turbulence. To probe the properties of such relativistic particles, we perform magnetohydrodynamic simulations to obtain the turbulent fields generated by the MRI, and calculate orbits of the high-energy particles using snapshot data of the MRI turbulence. We find that the particle acceleration is described by a diffusion phenomenon in energy space with a diffusion coefficient of the hard-sphere type: Dε ∝ ε2, where ε is the particle energy. Eddies in the largest scale of the turbulence play a dominant role in the acceleration process. On the other hand, the stochastic behaviour in configuration space is not usual diffusion but superdiffusion: the radial displacement increases with time faster than that in the normal diffusion. Also, the magnetic field configuration in the hot accretion flow creates outward bulk motion of high-energy particles. This bulk motion is more effective than the diffusive motion for higher energy particles. Our results imply that typical active galactic nuclei that host hot accretion flows can accelerate CRs up to ε ∼ 0.1−10 PeV.

THE WEBT CAMPAIGN ON 3C279 IN 2006

2008 ◽  
Vol 17 (09) ◽  
pp. 1503-1513
Author(s):  
M. BÖTTCHER
Keyword(s):  
Magnetic Field ◽  
Time Scale ◽  
High Energy ◽  
Field Configuration ◽  
Characteristic Time Scale ◽  
X Ray ◽  
Very High Energy ◽  
Order Of Magnitude ◽  
Γ Ray ◽  
Optical Flux

The quasar 3C 279 was the target of an extensive multiwavelength monitoring campaign from January through April 2006, including an optical-IR-radio Whole Earth Blazar Telescope (WEBT) campaign and Target of Opportunity X-ray and soft γ-ray observations with Chandra and INTEGRAL in mid-January 2006, with additional X-ray coverage by RXTE and Swift XRT as well as independent very-high-energy (VHE) γ-ray observations by MAGIC, which led to the first-ever reported tentative detection of a quasar at VHE γ-rays. In this paper we summarize the results of the WEBT campaign. The source exhibited substantial variability of optical flux and spectral shape, with a characteristic time scale of a few days. The variability patterns throughout the optical BVRI bands were very closely correlated with each other, while there was no obvious correlation between the optical and radio variability. In intriguing contrast to other (in particular, BL Lac type) blazars, we find a lag of shorter-wavelength behind longer-wavelength variability throughout the RVB wavelength ranges, with a time delay increasing with increasing frequency. Spectral hardening during flares appears delayed with respect to a rising optical flux. This, in combination with the very steep IR-optical continuum spectral index of αo ~ 1.5 – 2.0, may indicate a highly oblique magnetic field configuration near the base of the jet, leading to inefficient particle acceleration and a very steep electron injection spectrum. An alternative explanation through a slow (time scale of several days) acceleration mechanism would require an unusually low magnetic field of B < 0.2 G , about an order of magnitude lower than inferred from previous analyses of simultaneous SEDs of 3C 279 and other FSRQs with similar properties.

Axial and radial development of the hot electron distribution in a helicon plasma source, measured by a retarding field energy analyzer (RFEA)

2022 ◽  
Author(s):  
Lisa Buschmann ◽  
Ashild Fredriksen
Keyword(s):  
Magnetic Field ◽  
Electron Distribution ◽  
Potential Drop ◽  
Plasma Source ◽  
High Energy ◽  
Plasma Potential ◽  
Field Configuration ◽  
Field Energy ◽  
Hot Electron ◽  
High Energy Tail

Abstract The information about the electron population of a helicon source plasma that expands along a magnetic nozzle is important for understanding the plasma acceleration across the potential drop that forms in the nozzle. The electrons need an energy higher than the potential drop to escape from the source. At these energies the signal of a Langmuir probe is less accurate. An inverted RFEA measures the high-energy tail of the electrons. To reach the probe, they must have energies above the plasma potential VP, which can vary over the region of the measurement. By constructing a full distribution by applying the electron temperature Te obtained from the electron IV-curve and the VP obtained from the ion collecting RFEA or an emissive probe, a density measure of the hot electron distribution independent of VP can be obtained. The variation of the high-energy tail of the EEDF in both radial and axial directions, in the two different cases of 1) a purely expanding magnetic field nozzle, and 2) a more constricted one by applying current in a third, downstream coil was investigated. The electron densities and temperatures from the source are then compared to two analytic models of the downstream development of the electron density. The first model considers the development for a pure Boltzmann distribution while the second model takes an additional magnetic field expansion into account. A good match between the measured densities and the second model was found for both configurations. The RFEA probe also allows for directional measurement of the electron current to the probe. This property is used to compare the densities from the downstream and upstream directions, showing a much lower contribution of downstream electrons into the source for a purely expanding magnetic field in comparison to the confined magnetic field configuration.

Analysis of the performance of electrodynamic tethers with autonomous electron generation

2020 ◽  
Author(s):  
P.M. Bechasnov
Keyword(s):  
Magnetic Field ◽  
Specific Impulse ◽  
High Energy ◽  
Rocket Engines ◽  
Jet Engines ◽  
Electron Generation ◽  
Rocket Thrust ◽  
Electrodynamic Tethers ◽  
Rapid Deceleration ◽  
A Current

Currently, electric rocket engines have largely reached the efficiency limits determined by the principle of rocket thrust. Electrodynamic tethers, interacting with an external magnetic field and actually being jet engines, are devoid of such restrictions. However, their thrust is limited by the concentration of the external plasma and depends on its fluctuations. The paper is the first to propose to create a current in the tether by propellant ionization, receiving a large thrust from a relatively short tether and a strong magnetic field deflecting charged cosmic particles. The numerical analysis showed that the length of the tether of hundreds of meters near the Earth provides a specific impulse of up to hundreds of kilometers per second and its proper acceleration of the power plant at a level of 0.01 m / s2, as well as protection of the central region of the tether from particles with an energy of more than 1 MeV. This makes it possible to consider it for maneuvering satellites with practically no restrictions on the delta-V, for performing fast high-energy inter-orbital flights and for radiation protection of a high-latitude orbital station. In the future, such a tether can be used for rapid deceleration of orbital objects, launching into geostationary orbit, interplanetary transfers and protection of objects from charged particles. The study describes possible areas of application and directions for further research of the concept of such a tether.

scholarly journals Ion Current Screening Modeling of the Ion–Weibel Instability

2022 ◽  
Vol 924 (2) ◽  
pp. 89
Author(s):  
J. L. Jiao
Keyword(s):  
Magnetic Field ◽  
Computational Efficiency ◽  
Supernova Remnants ◽  
Large Scale ◽  
High Energy ◽  
Ion Current ◽  
Weibel Instability ◽  
Particle In Cell ◽  
High Energy Cosmic Rays ◽  
Pic Method

Abstract Ion–Weibel instability (IWI) is an important mechanism of generating a magnetic field in supernova remnants; it plays a key role in the generation of high-energy cosmic rays. Computational efficiency has been a bottleneck in numerical exploration of the large-scale evolution of IWI. Here I report a new hybrid particle-in-cell (PIC) method that can quickly simulate IWI. The method is based on a new model that describes the relation of the ion current and its magnetic field under the electron screening. The new method’s computational efficiency is nearly two orders of magnitude higher than that of the PIC method. This method is suitable for the full-scale simulation of the IWI in laser-plasma experiments and supernova remnants.

scholarly journals Electron pitch-angle diffusion: resonant scattering by waves vs. nonadiabatic effects

2013 ◽  
Vol 31 (9) ◽  
pp. 1485-1490 ◽  
Author(s):  
A. V. Artemyev ◽  
K. G. Orlova ◽  
D. Mourenas ◽  
O. V. Agapitov ◽  
V. V. Krasnoselskikh
Keyword(s):  
Magnetic Field ◽  
Pitch Angle ◽  
Resonant Scattering ◽  
High Energy ◽  
Field Configuration ◽  
Particle Energy ◽  
Inner Magnetosphere ◽  
Resonant Wave ◽  
Night Side ◽  
Nonadiabatic Effects

Abstract. In this paper we investigate the electron pitch-angle diffusion coefficients in the night-side inner magnetosphere around the geostationary orbit (L ~ 7) due to magnetic field deformation. We compare the effects of resonant wave–particle scattering by lower band chorus waves and the adiabaticity violation of electron motion due to the strong curvature of field lines in the vicinity of the equator. For a realistic magnetic field configuration, the nonadiabatic effects are more important than the wave–particle interactions for high energy (> 1 MeV) electrons. For smaller energy, the scattering by waves is more effective than nonadiabatic one. Moreover, the role of nonadiabatic effects increases with particle energy. Therefore, to model electron scattering and transport in the night-side inner magnetosphere, it is important to take into account the peculiarities of high-energy electron dynamics.

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