Observation of bistable density transitions in magnetized plasma by voltage-biased electrode

Shinohara, Shunjiro; Matsuyama, S.

doi:10.1063/1.1516217

Cited by 10 publications

(6 citation statements)

References 33 publications

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“…a change of Mach number of 1 with a distance approximately equal to the ion Larmor radius [141,142,145]. Here, under certain conditions, bistable density transitions, which have similar behaviors of L/H transitions in fusion torus machines with a key of a radial electric field [146], were found and analyzed from the spatio-temporal behaviors [145,147,148]. This biasing can also play an important role to suppress the electrostatic drift instabilities, which are described in subsection 3.1.2.…”

Section: Control/understanding Of Basic Plasma Performancementioning

confidence: 92%

Helicon high-density plasma sources: physics and applications

Shinohara

2018

Advances in Physics: X

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Helicon high-density (up to ~10 13 cm −3) plasma sources using a radio frequency wave in the presence of a magnetic field under a low pressure are very promising for various application fields owing to the flexibility of external operational parameters. In addition, these sources have interesting inherent characteristics. Herein, the basic features of helicon wave plasmas including production mechanisms are briefly described, focusing on some similarities to other fields. Examples of specific helicon sources are also introduced. Then, an extensive variety of applications ranging from fundamental to practical applications, which are very influential for further development in each field, are introduced, emphasizing crucial points.

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Section: Control/understanding Of Basic Plasma Performancementioning

confidence: 92%

Helicon high-density plasma sources: physics and applications

Shinohara

2018

Advances in Physics: X

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“…These include the control of the radial density profile and the high azimuthal plasma rotation with a high velocity shear, [27][28][29][30][31][32] a proof of principle experiment on ion mass separation, 33 and the self-excited, density-transition phenomenon in the bistable system. 28,34,35 Using this device with the plasma diameter reduced to 5 cm ͑the axial length was maintained at 170 cm͒, we have characterized in detail the highdensity helicon production and radio frequency ͑rf͒ wave phenomena, [36][37][38][39][40][41][42][43] which included the analyses of various antenna geometries. Drift wave turbulence, which is important for transport phenomena in magnetic confinement devices and for an understanding of fundamental processes, has been extensively investigated using a plasma diameter of 10 cm with the above device and the modified device.…”

Section: Introductionmentioning

confidence: 99%

Development of high-density helicon plasma sources and their applications

et al. 2009

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We report on the development of unique, high-density helicon plasma sources and describe their applications. Characterization of one of the largest helicon plasma sources yet constructed is made. Scalings of the particle production efficiency are derived from various plasma production devices in open literature and our own data from long and short cylinder devices, i.e., high and low values of the aspect ratio A ͑the ratio of the axial length to the diameter͒, considering the power balance in the framework of a simple diffusion model. A high plasma production efficiency is demonstrated, and we clarify the structures of the excited waves in the low A region down to 0.075 ͑the large device diameter of 73.8 cm with the axial length as short as 5.5 cm͒. We describe the application to plasma propulsion using a new concept that employs no electrodes. A very small diameter ͑2.5 cm͒ helicon plasma with 10 13 cm −3 density is produced, and the preliminary results of electromagnetic plasma acceleration are briefly described.

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“…In mirror devices, the stabilization of low-frequency instabilities and wave excitation with a strong shear has been realized along with bistable density transitions by voltage biasing. [8][9][10][11][12][13][14][15][16] Recently, by this biasing scheme, toroidal rotation has also been studied with an internal ring trap device. 17) However, in contrast to this active research, there have been few experiments 14,[18][19][20][21] to show a large change of the density profile with high azimuthal rotation velocity in a controlled manner by biasing to multiple electrodes from a fundamental viewpoint.…”

Section: Introductionmentioning

confidence: 99%

Initial Trial of Plasma Mass Separation by Crossed Electric and Magnetic Fields

Shinohara

Horii

2007

jjap

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Using segmented concentric rings to produce a radial electric field, an initial trial experiment on ion mass separation in a magnetized plasma with low collisionality has been successfully carried out. With the increase in electric field or the decrease in magnetic field, the azimuthal flow velocity in the Xe plasma saturated and then it decayed due to the unconfined condition. On the other hand, the Ar plasma, whose mass is lighter than the Xe one, did not show this behavior in this operational region. These results are consistent with a particle orbit analysis and a simple calculation of the balances of forces.

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Observation of bistable density transitions in magnetized plasma by voltage-biased electrode

Cited by 10 publications

References 33 publications

Helicon high-density plasma sources: physics and applications

Helicon high-density plasma sources: physics and applications

Development of high-density helicon plasma sources and their applications

Initial Trial of Plasma Mass Separation by Crossed Electric and Magnetic Fields

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