Measurement of the Density Profile of a Toroidal Non-neutral Plasma with a Wall-Probe Array

Saitoh, H.; Yano, Yoshihisa; Mizushima, T.; Morikawa, Junji; Yoshida, Zensho

doi:10.1585/pfr.4.054

Cited by 8 publications

(6 citation statements)

References 22 publications

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“…When the beam current is stopped (t ¼ 0:32 s), the plasma becomes turbulent and then relaxes into a quiescent state, in which the fluctuation level is less than 1%; through the transient turbulent phase, the driven state reorganizes into the confined state. By ''triangulation,'' using an array of wall probes, we can estimate the location of the charged clump [28]. Electrons in the outer region (intersecting the electron gun) are lost immediately after the beam is stopped.…”

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confidence: 99%

Magnetospheric Vortex Formation: Self-Organized Confinement of Charged Particles

et al. 2010

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A magnetospheric configuration gives rise to various peculiar plasma phenomena that pose conundrums to astrophysical studies; at the same time, innovative technologies may draw on the rich physics of magnetospheric plasmas. We have created a "laboratory magnetosphere" with a levitating superconducting ring magnet. Here we show that charged particles (electrons) self-organize a stable vortex, in which particles diffuse inward to steepen the density gradient. The rotating electron cloud is sustained for more than 300 s. Because of its simple geometry and self-organization, this system will have wide applications in confining single- and multispecies charged particles.

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confidence: 99%

Magnetospheric Vortex Formation: Self-Organized Confinement of Charged Particles

et al. 2010

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“…1(a) as N2, N3, and N4, 29 and the spatial resolution of the measurements was not very high. We assume that the electron density has power-low dependence on r on the z ¼ 0 plane…”

Section: Inward Diffusion Of Particlesmentioning

confidence: 99%

“…29 If we can divide the whole plasma volume into m regions and the averaged electron density at each region is n i (i ¼ 1 À m), image charge Q j (j ¼ 1 À m) induced on each wall is given by…”

Section: Inward Diffusion Of Particlesmentioning

confidence: 99%

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Formation of high-β plasma and stable confinement of toroidal electron plasma in Ring Trap 1

et al. 2011

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Formation of high-b electron cyclotron resonance heating plasma and stable confinement of pure electron plasma have been realized in the Ring Trap 1 device, a magnetospheric configuration generated by a levitated dipole field magnet. The effects of coil levitation resulted in drastic improvements of the confinement properties, and the maximum local b value has exceeded 70%. Hot electrons are major component of electron populations, and its particle confinement time is 0.5 s. Plasma has a peaked density profile in strong field region [H. Saitoh et al., 23rd IAEA Fusion Energy Conference EXC/9-4Rb (2010)]. In pure electron plasma experiment, inward particle diffusion is realized, and electrons are stably trapped for more than 300 s. When the plasma is in turbulent state during beam injection, plasma flow has a shear, which activates the diocotron (Kelvin-Helmholtz) instability. The canonical angular momentum of the particle is not conserved in this phase, realizing the radial diffusion of charged particles across closed magnetic surfaces.

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“…31. The longest applicable integration time in the present experimental setup is about 10 s. More detailed description on the measurements of E r and techniques for estimating the spatial profiles of plasma using wall probes are reported in Ref.…”

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confidence: 99%

Confinement of electron plasma by levitating dipole magnet

et al. 2010

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A recent experiment on the Ring Trap 1 device has demonstrated long-term (exceeding 300 s) confinement of non-neutral (pure electron) plasma in a dipole magnetic field; particles diffuse inward, steepening the density gradient and self-organizing into a stable vortex structure [Z. Yoshida et al., Phys. Rev. Lett. 104, 235004 (2010)]. In this study, the internal structures of the plasma are experimentally investigated, and it is shown that the observations are consistent with rigidly rotating charged particle clump. The radial profiles of electrostatic potential and electron density consistently show that the drift velocity has homogeneous angular frequency in the confinement region. The electrostatic fluctuations also rotate rigidly with a phase velocity that agrees with the drift velocity. The magnetospheric system should have a wide application in confining single-species and even multiple-species charged particles.

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Measurement of the Density Profile of a Toroidal Non-neutral Plasma with a Wall-Probe Array

Cited by 8 publications

References 22 publications

Magnetospheric Vortex Formation: Self-Organized Confinement of Charged Particles

Magnetospheric Vortex Formation: Self-Organized Confinement of Charged Particles

Formation of high-β plasma and stable confinement of toroidal electron plasma in Ring Trap 1

Confinement of electron plasma by levitating dipole magnet

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