Simultaneous Measurements of Local Axial and Radial Momentum Fluxes near a Radial Wall of a Helicon Source

Sugawara, Takeharu; Takahashi, Kazunori; Andõ, Akira

doi:10.1585/pfr.14.1301143

Cited by 2 publications

(2 citation statements)

References 26 publications

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“…Momentum vector measurement instruments. Figure 7 shows the detailed structure of the momentum vector measurement instrument (MVMI), which is very similar to the previous bench test 34 and the preliminarily test in plasmas 50 . The whole structure of the MVMI is flipped from the previous configuration to stabilize the equilibrium position of the axial pendulum when moving the whole structure by the motor stage.…”

Section: Methodsmentioning

confidence: 80%

Spatially- and vector-resolved momentum flux lost to a wall in a magnetic nozzle rf plasma thruster

Takahashi

Sugawara

Andõ

2020

Sci Rep

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Most of the artificial low-pressure plasmas contact with physical walls in laboratories; the plasma loss at the wall significantly affects the plasma device performance, e.g., an electric propulsion device. Near the surface of the wall, ions are spontaneously accelerated by a sheath and deliver their momentum and energy to the wall, while most of the electrons are reflected there. The momentum flux of the ions is a vector field, i.e., having both the radial and axial components even if the azimuthal components are neglected in a cylindrical system. Here the spatially-and vector-resolved measurement of the momentum flux near the cylindrical source wall of a magnetic nozzle radiofrequency (rf) plasma thruster configuration is successfully demonstrated by using a momentum vector measurement instrument. The results experimentally identify the spatial profile of a non-negligible axial momentum flux to the wall, while the radially accelerated ions seem to be responsible for the energy loss to the wall. The spatial profiles of the radial and axial momentum fluxes and the energy lost to the wall are significantly affected by the magnetic field strength. The results contribute to understand how and where the momentum and energy in the artificial plasma devices are lost, in addition to the presently tested thruster. The plasma momentum is one of the fundamental physical quantities associated with static and dynamic phenomena of plasmas in nature and laboratories. The energy flux being a scalar quantity can be given by the magnitude of the velocity, while the momentum flux is a vector quantity in general. It is crucial to understand and characterize the momentum transport, conversion, gain, and loss mechanisms for clarifying the structural formation of plasmas such as the astrophysical jets 1 , the particle acceleration in auroras at the Earth and Jupiter 2,3 , the coronal mass ejection from the Sun 4 , the interaction between the plasmas and the geomagnetic field 5 , and so on. In these naturally appearing plasmas, the processes involving the momentum and energy transfer occur due to the interaction with electromagnetic fields, collisions, turbulences, and so on, since they cannot see any physical boundaries in space except for the surface of planets. Terrestrial artificial plasmas ubiquitously contact to physical boundaries; forming a sheath maintaining charge balance in plasmas 6. Plasma-wall interactions involving the momentum transfer and loss also significantly affect the plasma behavior in the laboratories, e.g., in ref. 7,8 , in addition to the interactions occurring in the above-mentioned natural plasmas, e.g., interaction with the magnetic fields 9-11. The electric field perpendicular to the physical boundary is spontaneously formed in the sheath and accelerates the ions toward the boundary; resulting in the transfer of the momentum flux perpendicular to the surface. However, if they have velocity components parallel to the boundary surface, they can also deliver their momentum parallel to the boundary. Therefore,...

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Section: Methodsmentioning

confidence: 80%

Spatially- and vector-resolved momentum flux lost to a wall in a magnetic nozzle rf plasma thruster

Takahashi

Sugawara

Andõ

2020

Sci Rep

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“…5, where the axial and radial forces exerted on the detector plate surface can be transmitted to the axially movable pendulum and the rotatable pivot structure, respectively. The displacements for both cases are measured using displacement sensors [46,47]. the magnetic field strength.…”

Section: Space Electric Propulsionmentioning

confidence: 99%

Magnetic Nozzle Radiofrequency Plasma Systems for Space Propulsion, Industry, and Fusion Plasmas

TAKAHASHI

Charles

Boswell

et al. 2023

Plasma and Fusion Research

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Low-pressure radiofrequency (rf) plasma sources have been widely used in various fields. When static magnetic fields are applied to these sources, a diverging magnetic field configuration known as a magnetic nozzle forms downstream of the source and interesting phenomena are observed. Such structures are frequently observed in space, e.g., the surface of the Sun and the geomagnetic fields. Here, the studies performed by the authors over the last decade on the fundamental plasma physics, the space plasma propulsion, the industrial plasma technology, and the radiofrequency ion source, are briefly overviewed. The design of sources based on the type of application is an important issue. Integrating a rf plasma source into a system often requires a compact and automatically controlled system, as presented here. Herein, interaction between the low-temperature plasmas and the hot fusion plasmas is sometimes mentioned in terms of "Plasma Apparatus."

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Simultaneous Measurements of Local Axial and Radial Momentum Fluxes near a Radial Wall of a Helicon Source

Cited by 2 publications

References 26 publications

Spatially- and vector-resolved momentum flux lost to a wall in a magnetic nozzle rf plasma thruster

Spatially- and vector-resolved momentum flux lost to a wall in a magnetic nozzle rf plasma thruster

Magnetic Nozzle Radiofrequency Plasma Systems for Space Propulsion, Industry, and Fusion Plasmas

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