Observation of particle acceleration in laboratory magnetosphere

Physics of Plasmas 22 (2015)

Y Kawazura, Z Yoshida, M Nishiura, H Saitoh, Y Yano, T Nogami, N Sato, M Yamasaki, A Kashyap, T Mushiake

© 2015 AIP Publishing LLC. The self-organization of magnetospheric plasma is brought about by inward diffusion of magnetized particles. Not only creating a density gradient toward the center of a dipole magnetic field, the inward diffusion also accelerates particles and provides a planetary radiation belt with high energy particles. Here, we report the first experimental observation of a "laboratory radiation belt" created in the ring trap 1 device. By spectroscopic measurement, we found an appreciable anisotropy in the ion temperature, proving the betatron acceleration mechanism which heats particles in the perpendicular direction with respect to the magnetic field when particles move inward. The energy balance model, including the heating mechanism, explains the observed ion temperature profile.

Hamiltonian formalism of extended magnetohydrodynamics

Journal of Physics A: Mathematical and Theoretical 48 (2015)

HM Abdelhamid, Y Kawazura, Z Yoshida

© 2015 IOP Publishing Ltd. The extended magnetohydrodynamics (MHD) system, including the Hall effect and the electron inertia effect, has a Hamiltonian structure embodied by a noncanonical Poisson algebra on an infinite-dimensional phase space. A nontrivial part of the formulation is the proof of Jacobis identity for the Poisson bracket. We unearth a basic Lie algebra that generates the Poisson bracket. A class of similar Poisson algebra may be generated by the same Lie algebra, which encompasses the Hall MHD system and inertial MHD system.

Improved beta (local beta > 1) and density in electron cyclotron resonance heating on the RT-1 magnetosphere plasma

Nuclear Fusion 55 (2015)

M Nishiura, Z Yoshida, H Saitoh, Y Yano, Y Kawazura, T Nogami, M Yamasaki, T Mushiake, A Kashyap

© 2015 IAEA. This study reports the recent progress in improved plasma parameters of the RT-1 device. Increased input power and the optimized polarization of electron cyclotron resonance heating (ECRH) with an 8.2 GHz klystron produce a significant increase in electron beta, which is evaluated by an equilibrium analysis of the Grad-Shafranov equation. The peak value of the local electron beta β < inf > e < /inf > is found to exceed 1. In the high-beta and high-density regime, the density limit is observed for H, D and He plasmas. The line-averaged density is close to the cutoff density for 8.2 GHz ECRH. When the filling gas pressure is increased, the density limit still exists even in the low-beta region. This result indicates that the density limit is caused by the cutoff density rather than the beta limit. From the analysis of interferometer data, we found that inward diffusion causes a peaked density profile beyond the cutoff density.

Measurement of a density profile of a hot-electron plasma in RT-1 with three-chord interferometry

Physics of Plasmas 22 (2015)

H Saitoh, Y Yano, Z Yoshida, M Nishiura, J Morikawa, Y Kawazura, T Nogami, M Yamasaki

© 2015 AIP Publishing LLC. The electron density profile of a plasma in a magnetospheric dipole field configuration was measured with a multi-chord interferometry including a relativistic correction. In order to improve the accuracy of density reconstruction, a 75 GHz interferometer was installed at a vertical chord of the Ring Trap 1 (RT-1) device in addition to previously installed ones at tangential and another vertical chords. The density profile was calculated by using the data of three-chord interferometry including relativistic effects for a plasma consisting of hot and cold electrons generated by electron cyclotron resonance heating (ECH). The results clearly showed the effects of density peaking and magnetic mirror trapping in a strongly inhomogeneous dipole magnetic field.

Editorial Special issue: Macroscopic randomness in astrophysical plasmas: The legacy and vision of Ya. B. Zeldovich


A Shukurov, D Sokoloff, A Schekochihin

The impact of accretion disc winds on the optical spectra of cataclysmic variables

Monthly Notices of the Royal Astronomical Society 450 (2015) 3331-3344

JH Matthews, C Knigge, KS Long, SA Sim, N Higginbottom

Gas flow in barred potentials - III. Effects of varying the quadrupole


MC Sormani, J Binney, J Magorrian

Overview of MAST results

NUCLEAR FUSION 55 (2015) ARTN 104008

IT Chapman, J Adamek, RJ Akers, S Allan, L Appel, O Asunta, M Barnes, N Ben Ayed, T Bigelow, W Boeglin, J Bradley, J Bruenner, P Cahyna, M Carr, J Caughman, M Cecconello, C Challis, S Chapman, J Chorley, G Colyer, N Conway, WA Cooper, M Cox, N Crocker, B Crowley, G Cunningham, A Danilov, D Darrow, R Dendy, A Diallo, D Dickinson, S Diem, W Dorland, B Dudson, D Dunai, L Easy, S Elmore, A Field, G Fishpool, M Fox, E Fredrickson, S Freethy, L Garzotti, YC Ghim, K Gibson, J Graves, C Gurl, W Guttenfelder, C Ham, J Harrison, D Harting, E Havlickova, J Hawke, N Hawkes, T Hender, S Henderson, E Highcock, J Hillesheim, B Hnat, J Holgate, J Horacek, J Howard, B Huang, K Imada, O Jones, S Kaye, D Keeling, A Kirk, I Klimek, M Kocan, H Leggate, M Lilley, B Lipschultz, S Lisgo, YQ Liu, B Lloyd, B Lomanowski, I Lupelli, G Maddison, J Mailloux, R Martin, G McArdle, K McClements, B McMillan, A Meakins, H Meyer, C Michael, F Militello, J Milnes, AW Morris, G Motojima, D Muir, E Nardon, V Naulin, G Naylor, A Nielsen, M O'Brien, T O'Gorman, Y Ono, H Oliver, S Pamela, L Pangione, F Parra, A Patel, W Peebles, M Peng, R Perez, S Pinches, L Piron, M Podesta, M Price, M Reinke, Y Ren, C Roach, J Robinson, M Romanelli, V Rozhansky, S Saarelma, S Sangaroon, A Saveliev, R Scannell, A Schekochihin, S Sharapov, R Sharples, V Shevchenko, S Silburn, J Simpson, J Storrs, Y Takase, H Tanabe, H Tanaka, D Taylor, G Taylor, D Thomas, N Thomas-Davies, A Thornton, M Turnyanskiy, M Valovic, R Vann, N Walkden, H Wilson, LV Wyk, T Yamada, S Zoletnik, MAST Team, MASTU Team

The distribution function of the Galaxy's dark halo


J Binney, T Piffl

Internal alignments of red versus blue discs in dark matter haloes

Monthly Notices of the Royal Astronomical Society 452 (2015) 4094-4110

VP Debattista, FC Van Den Bosch, R Roškar, T Quinn, B Moore, DR Cole

© 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. Large surveys have shown that red galaxies are preferentially aligned with their haloes, while blue galaxies have a more isotropic distribution. Since haloes generally align with their filaments, this introduces a bias in the measurement of the cosmic shear from weak lensing. It is therefore vitally important to understand why this difference arises. We explore the stability of different disc orientations within triaxial haloes. We show that, in the absence of gas, the disc orientation is most stable when its spin is along the minor axis of the halo. Instead when gas cools on to a disc, it is able to form in almost arbitrary orientation, including offthe main planes of the halo (but avoiding an orientation perpendicular to the halo's intermediate axis). Substructure helps gasless galaxies reach alignment with the halo faster, but has less effect on galaxies when gas is cooling on to the disc. Our results provide a novel and natural interpretation for why red, gas poor galaxies are preferentially aligned with their halo, while blue, star-forming, galaxies have nearly random orientations, without requiring a connection between galaxies' current star formation rate and their merger history.

Gas density fluctuations in the Perseus Cluster: clumping factor and velocity power spectrum


I Zhuravleva, E Churazov, P Arevalo, AA Schekochihin, SW Allen, AC Fabian, WR Forman, JS Sanders, A Simionescu, R Sunyaev, A Vikhlinin, N Werner

Fluctuation-dissipation relations for a plasma-kinetic Langevin equation

Journal of Plasma Physics 81 (2015)

A Kanekar, AA Schekochihin, W Dorland, NF Loureiro

© 2014 Cambridge University Press. A linearised kinetic equation describing electrostatic perturbations of a Maxwellian equilibrium in a weakly collisional plasma forced by a random source is considered. The problem is treated as a kinetic analogue of the Langevin equation and the corresponding fluctuation-dissipation relations are derived. The kinetic fluctuation-dissipation relation reduces to the standard fluid one in the regime where the Landau damping rate is small and the system has no real frequency; in this case the simplest possible Landau-fluid closure of the kinetic equation coincides with the standard Langevin equation. Phase mixing of density fluctuations and emergence of fine scales in velocity space is diagnosed as a constant flux of free energy in Hermite space; the fluctuation-dissipation relations for the perturbations of the distribution function are derived, in the form of a universal expression for the Hermite spectrum of the free energy. Finite-collisionality effects are included. This work is aimed at establishing the simplest fluctuation-dissipation relations for a kinetic plasma, clarifying the connection between Landau and Hermite-space formalisms, and setting a benchmark case for a study of phase mixing in turbulent plasmas.

Identification of globular cluster stars in RAVE data - I. Application to stellar parameter calibration


B Anguiano, DB Zucker, R-D Scholz, EK Grebel, G Seabroke, A Kunder, J Binney, PJ McMillan, T Zwitter, RFG Wyse, G Kordopatis, O Bienayme, J Bland-Hawthorn, C Boeche, KC Freeman, BK Gibson, G Gilmore, U Munari, J Navarro, Q Parker, W Reid, A Siebert, A Siviero, M Steinmetz, F Watson

The Gaia-ESO Survey: Empirical determination of the precision of stellar radial velocities and projected rotation velocities


RJ Jackson, RD Jeffries, J Lewis, SE Koposov, GG Sacco, S Randich, G Gilmore, M Asplund, J Binney, P Bonifacio, JE Drew, S Feltzing, AMN Ferguson, G Micela, I Neguerela, T Prusti, H-W Rix, A Vallenari, EJ Alfaro, CA Prieto, C Babusiaux, T Bensby, R Blomme, A Bragaglia, E Flaccomio, P Francois, N Hambly, M Irwin, AJ Korn, AC Lanzafame, E Pancino, A Recio-Blanco, R Smiljanic, S Van Eck, N Walton, A Bayo, M Bergemann, G Carraro, MT Costado, F Damiani, B Edvardsson, E Franciosini, A Frasca, U Heiter, V Hill, A Hourihane, P Jofre, C Lardo, P de Laverny, K Lind, L Magrini, G Marconi, C Martayan, T Masseron, L Monaco, L Morbidelli, L Prisinzano, L Sbordone, SG Sousa, CC Worley, S Zaggia

Origin of the high v(los) feature in the Galactic bar


M Aumer, R Schoenrich



R Schoenrich, M Aumer, SE Sale

Developed turbulence and nonlinear amplification of magnetic fields in laboratory and astrophysical plasmas.

Proceedings of the National Academy of Sciences of the United States of America 112 (2015) 8211-8215

J Meinecke, P Tzeferacos, A Bell, R Bingham, R Clarke, E Churazov, R Crowston, H Doyle, RP Drake, R Heathcote, M Koenig, Y Kuramitsu, C Kuranz, D Lee, M MacDonald, C Murphy, M Notley, H-S Park, A Pelka, A Ravasio, B Reville, Y Sakawa, W Wan, N Woolsey, R Yurchak, F Miniati, A Schekochihin, D Lamb, G Gregori

The visible matter in the universe is turbulent and magnetized. Turbulence in galaxy clusters is produced by mergers and by jets of the central galaxies and believed responsible for the amplification of magnetic fields. We report on experiments looking at the collision of two laser-produced plasma clouds, mimicking, in the laboratory, a cluster merger event. By measuring the spectrum of the density fluctuations, we infer developed, Kolmogorov-like turbulence. From spectral line broadening, we estimate a level of turbulence consistent with turbulent heating balancing radiative cooling, as it likely does in galaxy clusters. We show that the magnetic field is amplified by turbulent motions, reaching a nonlinear regime that is a precursor to turbulent dynamo. Thus, our experiment provides a promising platform for understanding the structure of turbulence and the amplification of magnetic fields in the universe.

Intrinsic rotation in tokamaks: theory


FI Parra, M Barnes

Dependence of intrinsic rotation reversals on collisionality in MAST

NUCLEAR FUSION 55 (2015) ARTN 032003

JC Hillesheim, FI Parra, M Barnes, NA Crocker, H Meyer, WA Peebles, R Scannell, A Thornton, MAST Team

Less constrained omnigeneous stellarators

NUCLEAR FUSION 55 (2015) ARTN 033005

FI Parra, I Calvo, P Helander, M Landreman