Stochastic ion heating by an electrostatic wave in a sheared magnetic field

1980 ◽  
Vol 23 (8) ◽  
pp. 1646 ◽  
Author(s):  
Y. Gell ◽  
R. Nakach
Keyword(s):  
Magnetic Field ◽  
Ion Heating ◽  
Electrostatic Wave

Ion beam excitation of ion-cyclotron waves and ion heating in plasmas with drifting ions

1978 ◽  
Vol 19 (2) ◽  
pp. 237-252 ◽  
Author(s):  
J. P. Hauck ◽  
H. Böhmer ◽  
N. Rynn ◽  
Gregory Benford
Keyword(s):  
Magnetic Field ◽  
Ion Beam ◽  
Ion Beams ◽  
Ion Heating ◽  
Ion Cyclotron Waves ◽  
Diffusion Effects ◽  
Ion Cyclotron ◽  
Cyclotron Mode ◽  
The Magnetic Field ◽  
Beam Excitation

Ion-cyclotron waves are excited by cesium and potassium ion beams in cesium and potassium Q-machine plasmas. The ion beams are injected along the magnetic field with care to avoid beam transverse velocities. The observed ion-cyclotron mode frequencies are below those driven by electron currents. These resonant instabilities are convective in character with small spatial growth rates ki/kr ≃ 0.05. Plasma ion heating is observed and is consistent with a model in which mode amplitudes are saturated by diffusion effects.

scholarly journals CLUSTER encounters with the high altitude cusp: boundary structure and magnetic field depletions

2004 ◽  
Vol 22 (5) ◽  
pp. 1739-1754 ◽  
Author(s):  
P. J. Cargill ◽  
M. W. Dunlop ◽  
B. Lavraud ◽  
R. C. Elphic ◽  
D. L. Holland ◽  
...  
Keyword(s):  
Magnetic Field ◽  
High Altitude ◽  
Plasma Flow ◽  
Boundary Structure ◽  
Tangential Discontinuity ◽  
Ion Heating ◽  
Rotational Discontinuity ◽  
Abstract Data ◽  
The Magnetic Field ◽  
Obvious Relation

Abstract. Data from the four spacecraft Cluster mission during a high altitude cusp crossing on 13 February 2001 are presented. The spacecraft configuration has one leading spacecraft, with the three trailing spacecraft lying in a plane that corresponds roughly to the nominal magnetopause surface. The typical spacecraft separation is approximately 600km. The encounter occurs under conditions of strong and steady southward Interplanetary Magnetic Field (IMF). The cusp is identified as a seven-minute long depression in the magnetic field, associated with ion heating and a high abundance of He+. Cusp entry involves passage through a magnetopause boundary that has undergone very significant distortion from its nominal shape, is moving rapidly, and exhibits structure on scales of the order of the spacecraft separation or less. This boundary is associated with a rotation of the magnetic field, a normal field component, and a plasma flow into the cusp of approximately 35 km/s. However, it cannot be identified positively as a rotational discontinuity. Exit from the cusp into the lobe is through a boundary that is initially sharp, but then retreats tailward at a few km/s. As the leading spacecraft passes through this boundary, there is a plasma flow out of the cusp of approximately 30km/s, suggesting that this is not a tangential discontinuity. A few minutes after exit from the cusp, the three trailing the spacecraft see a single cusp-like signature in the magnetic field. There is an associated temperature increase at two of the three trailing spacecraft. Timing measurements indicate that this is due to cusp-like regions detaching from the rear of the cusp boundary, and moving tailward. The magnetic field in the cusp is highly disordered, with no obvious relation between the four spacecraft, indicative of structure on scales

scholarly journals Lower Hybrid Drive in Solar Magnetic Reconnection Regions: Implications for Electron Acceleration and Solar Heating

2001 ◽  
Vol 18 (4) ◽  
pp. 336-344 ◽  
Author(s):  
Iver H. Cairns
Keyword(s):  
Magnetic Field ◽  
Magnetic Reconnection ◽  
Charge Exchange ◽  
Electron Acceleration ◽  
Solar Radio Emission ◽  
Lower Hybrid ◽  
Neutral Atmosphere ◽  
Ion Heating ◽  
Lower Corona ◽  
The Magnetic Field

AbstractLower hybrid (LH) drive involves the resonant acceleration of electrons parallel to the magnetic field by lower hybrid waves, often driven by ions with ring or ring-beam distributions. Charge-exchange between hydrogen atoms and protons with relative motions perpendicular to the magnetic field leads to ring distributions of pickup ions, with concomitant perpedicular ion ‘heating’. This paper considers the combination of LH drive and charge-exchange in the outflow regions of magnetic reconnection sites in the solar chromosphere and lower corona, showing that the combined mechanism naturally predicts major perpendicular ion heating and parallel electron acceleration, and exploring the mechanism’s relevance to specific solar reconnection phenomena, heating of the solar atmosphere, and production of energetic electrons that generate solar radio emission. Although primarily qualitative, analysis shows that the mechanism has numerous attractive aspects, including perpendicular ion heating that increases linearly with ion mass, parallel electron acceleration, predicted ion and electron temperatures that span those of the chromosphere and lower corona, and parallel electron speeds spanning those for type III bursts. Applications to chromospheric explosive events and low-lying active regions, and to heating the chromosphere, appear particularly suitable. Sweeping of plasma frozen-in to chromospheric and coronal magnetic field lines across the neutral atmosphere due to motions of sub-photospheric fields represents an obvious and important generalisation of the mechanism away from reconnection sites. The requirements that the neutrals not be strongly collisionally coupled to the plasma and that sufficient neutrals are available for charge-exchange restricts the LH drive mechanism to above the photosphere but below where the corona is essentially fully ionised. LH drive may thus be important in heating the chromosphere and low corona while other heating mechanisms dominate at higher altitudes. Although attractive thus far, quantitative analyses of LH drive in these contexts are necessary before definitive conclusions are reached.

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