Plasma density accumulation on a conical surface for diffusion along a diverging magnetic field

Saha, S. K.; Chowdhury, Satyajit; Janaki, M. S.; Ghosh, Abhijit; Hui, A. K.; Raychaudhuri, Santwana

doi:10.1063/1.4870758

Cited by 30 publications

(37 citation statements)

References 36 publications

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“…11a, b. This leakage of the high-energy electrons and/or the conical density profiles were observed regardless of the absence of the DL (Igarashi et al 2011;Saha et al 2014). The high-density conical structure downstream of the source is interpreted as the result of the local ionization by the energetic electrons Charles 2010).…”

Section: Electron Dynamicsmentioning

confidence: 87%

Helicon-type radiofrequency plasma thrusters and magnetic plasma nozzles

Takahashi

2019

Rev. Mod. Plasma Phys.

164

111

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Development of electrodeless radiofrequency plasma thrusters, e.g., a helicon thruster, has been one the of challenging topics for future high-power and longlived electric propulsion systems. The concept simply has a radiofrequency plasma production/heating source and a magnetic nozzle, while it seems to include many aspects of physics and engineering issues. The plasma produced inside the source is transported along the magnetic field lines and expands in the magnetic nozzle, where the plasma is spontaneously accelerated into the axial direction along the magnetic nozzle, yielding a generation of the thrust force. Hence, the plasma transport and spontaneous acceleration phenomena in the magnetic nozzle are key issues to improve the performance of the thrusters. Since the thrust is equal in magnitude and opposite in direction to momentum flux exhausted from the system, the direct measurement of the thrust can reveal not only the thruster performance but also fundamental physical quantity of plasma momentum flux. Here studies on fundamental physics relating to the thruster development and the technology for the compact and efficient system are reviewed; the current status of the thruster performance is shown. Finally, a recently proposed future new application of the thruster is also discussed.

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Section: Electron Dynamicsmentioning

confidence: 87%

Helicon-type radiofrequency plasma thrusters and magnetic plasma nozzles

Takahashi

2019

Rev. Mod. Plasma Phys.

164

111

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“…The yellow plateau in the figure indicates a small density of electrons with energies larger than 100 eV near the center of the plasma column. Saha et al [22] has earlier measured electrons with energies more than 100 eV in the center of the plasma in a similar experiment using a RFEA with a floating front grid and a fixed voltage electron repeller. The radial profile they obtained looks similar to the one we have for energies higher than 100 ev (less than −100 V).…”

Section: Resultsmentioning

confidence: 99%

“…Takahashi et al [10] and Charles [21] has proposed that the enhanced plasma density along the last field line is produced by an additional ionization from the high-energy electrons transported from the source along the field line. On the other hand Saha et al [22] has argued that the electric field set up between the positively charged ion beam region and the electrons following the field lines will accelerate the ion beam also radially giving rise to an oscillation that is responsible for the higher densities at the edges.…”

Section: Introductionmentioning

confidence: 99%

RFEA Measurements of High-Energy Electrons in a Helicon Plasma Device with Expanding Magnetic Field

Gulbrandsen

Fredriksen

2017

Front. Phys.

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In the inductively coupled plasma of the Njord helicon device we have, for the same parameters as for which an ion beam exists, measured a downstream population of high-energy electrons emerging from the source. Separated measurements of energetic tail electrons was carried out by Retarding Field Energy Analyzer (RFEA) with a grounded entrance grid, operated in an electron collection mode. In a radial scan with the RFEA pointed toward the source, we found a significant population of high-energy electrons just inside the magnetic field line mapping to the edge of the source. A second peak in high-energy electrons density was observed in a radial position corresponding to the radius of the source. Also, throughout the main column a small contribution of high-energy electrons was observed. In a radial scan with a RFEA biased to collect ions a localized increase in the plasma ion density near the magnetic field line emerging from the plasma near the wall of the source was observed. This is interpreted as a signature of high-energy electrons ionizing the neutral gas. Also, a dip in the floating potential of a Langmuir probe is evident in this region where high-energy electrons is observed.

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“…Charles [13] used retarding field energy analyzers (RFEAs) to discover the DL in a helicon plasma and the ion beam downstream of the DL. Recently, Saha et al [19] used RFEAs to measure the two-dimensional potential distribution. Kline et al [20] and Sun et al [21] used laser-induced fluorescence to detect the ion beam in a helicon plasma.…”

Section: Introductionmentioning

confidence: 99%

Study of axial double layer in helicon plasma by optical emission spectroscopy and simple probe

Zhao¹,

Zhu²,

Chen³

et al. 2018

Plasma Sci. Technol.

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Electron heating in a high-density helicon discharge B Clarenbach, M Krämer and B Lorenz -Thrust measurements in a low-magnetic field mode in the HDLT J Ling, M D West, T Lafleur et al. -Time-dependent gas density and temperature in Ar B Clarenbach, B Lorenz, M Krämer et al. - AbstractIn this work we used a passive measurement method based on a high-impedance electrostatic probe and an optical emission spectroscope (OES) to investigate the characteristics of the double layer (DL) in an argon helicon plasma. The DL can be confirmed by a rapid change in the plasma potential along the axis. The axial potential variation of the passive measurement shows that the DL forms near a region of strong magnetic field gradient when the plasma is operated in wavecoupled mode, and the DL strength increases at higher powers in this experiment. The emission intensity of the argon atom line, which is strongly dependent on the metastable atom concentration, shows a similar spatial distribution to the plasma potential along the axis. The emission intensity of the argon atom line and the argon ion line in the DL suggests the existence of an energetic electron population upstream of the DL. The electron density upstream is much higher than that downstream, which is mainly caused by these energetic electrons.

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Plasma density accumulation on a conical surface for diffusion along a diverging magnetic field

Cited by 30 publications

References 36 publications

Helicon-type radiofrequency plasma thrusters and magnetic plasma nozzles

Helicon-type radiofrequency plasma thrusters and magnetic plasma nozzles

RFEA Measurements of High-Energy Electrons in a Helicon Plasma Device with Expanding Magnetic Field

Study of axial double layer in helicon plasma by optical emission spectroscopy and simple probe

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