Experimental studies on ion acceleration and stream line detachment in a diverging magnetic field

Terasaka, Kenichiro; Yoshimura, S.; Ogiwara, Kohei; Aramaki, Mitsutoshi; Tanaka, Masayoshi Y.

doi:10.1063/1.3457139

Cited by 32 publications

(27 citation statements)

References 26 publications

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“…The phenomenon takes place in a globally current free jet, even if electrons remain fully magnetized and turn around with the field; only a negligible fraction of the ion flow is indeed pulled along with the electrons to maintain quasi-neutrality in the whole domain. This result is in agreement with the experimental observations [22]- [24], [26] of ion flux tube separation.…”

Section: Introductionsupporting

confidence: 93%

Influence of Electron and Ion Thermodynamics on the Magnetic Nozzle Plasma Expansion

Merino

Ahedo

2015

IEEE Trans. Plasma Sci.

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A two-fluid 2-D model of the supersonic plasma flow in a propulsive magnetic nozzle (MN) is extended to include simple electron and ion thermodynamics to study the effects of electron cooling and ion thermal energy on the expansion. A faster electron cooling rate is seen to reduce plasma jet divergence, increase radial rarefaction, and enhance detachment from the closed magnetic lines. Ion thermal energy is converted to directed kinetic energy by the MN without the mediation of an ambipolar electric field, and alters the electric response of the plasma.

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Section: Introductionsupporting

confidence: 93%

Influence of Electron and Ion Thermodynamics on the Magnetic Nozzle Plasma Expansion

Merino

Ahedo

2015

IEEE Trans. Plasma Sci.

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“…Cox et al 17 and Deline et al 18 observed that the half-width at halfmaximum of the radial density profile diverges less than the magnetic field, from which they conclude that ions have begun to detach from the MN. A similar conclusion was reached by Terasaka et al 19 using Mach probes to spatially map the three-dimensional ion velocity vector. Direct measurements of ion detachment were made using Faraday probe sweeps by Olsen et al 20 In contrast to the previous studies, Olsen et al observe that the ion streamlines of an ED-MN detach outward with respect to the diverging magnetic field.…”

Section: Introductionsupporting

confidence: 56%

Influence of the Applied Magnetic Field Strength on Flow Collimation in Magnetic Nozzles

Little¹,

Choueiri²

2014

50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference

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The influence of the magnetic field strength on the collimation of the plasma flow in an electron-driven magnetic nozzle is investigated experimentally. A collimated plasma flow is required for efficient plasma propulsion to minimize plume divergence losses. Faraday probe measurements are used to estimate the ion streamlines in the diverging field of the magnetic nozzle. It is found that decreasing the strength of the applied magnetic field invokes a transition from a collimated plume to an under-collimated plume, where an under-collimated plume is defined such that the plume divergence is greater than the magnetic field divergence. Langmuir and emissive probe measurements reveal that the transition to an under-collimated plume is accompanied by anomalous deceleration of the ion beam along the nozzle centerline, broadening of the transverse density profile, and the disappearance of an ion-confining potential well at the plasma periphery. This transition offers a guideline for reducing the plume divergence of an electron-driven magnetic nozzle.

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“…Inwards ion separation has been observed in several recent experiments. [22][23][24][25] Outwards ion separation, which requires outwards electron separation, has been observed too. 25 The outwards separation of electron streamtubes implies that a stronger radial electric field is needed to pull ions towards the more divergent beam edge and satisfy quasineutrality there.…”

Section: A Plasma Expansion Featuresmentioning

confidence: 99%

Two-dimensional plasma expansion in a magnetic nozzle: Separation due to electron inertia

Ahedo

Merino

2012

Physics of Plasmas

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A previous axisymmetric model of the supersonic expansion of a collisionless, hot plasma in a divergent magnetic nozzle is extended here in order to include electron-inertia effects. Up to dominant order on all components of the electron velocity, electron momentum equations still reduce to three conservation laws. Electron inertia leads to outward electron separation from the magnetic streamtubes. The progressive plasma filling of the adjacent vacuum region is consistent with electron-inertia being part of finite electron Larmor radius effects, which increase downstream and eventually demagnetize the plasma. Current ambipolarity is not fulfilled and ion separation can be either outwards or inwards of magnetic streamtubes, depending on their magnetization. Electron separation penalizes slightly the plume efficiency and is larger for plasma beams injected with large pressure gradients. An alternative nonzero electron-inertia model [E. Hooper, J. Propul. Power 9, 757 (1993)] based on cold plasmas and current ambipolarity, which predicts inwards electron separation, is discussed critically. A possible competition of the gyroviscous force with electron-inertia effects is commented briefly. V C 2012 American Institute of Physics. [http://dx

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Experimental studies on ion acceleration and stream line detachment in a diverging magnetic field

Cited by 32 publications

References 26 publications

Influence of Electron and Ion Thermodynamics on the Magnetic Nozzle Plasma Expansion

Influence of Electron and Ion Thermodynamics on the Magnetic Nozzle Plasma Expansion

Influence of the Applied Magnetic Field Strength on Flow Collimation in Magnetic Nozzles

Two-dimensional plasma expansion in a magnetic nozzle: Separation due to electron inertia

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