Plasma instability at an X-type magnetic neutral point

Baum, P. J.

doi:10.1063/1.1694548

Cited by 40 publications

(9 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In contrast, the flash phase of the solar flare is commonly believed to be due to an 'active' neutral sheet, in which plasma moves in at least two dimensions at a significant fraction of the Alfvdn speed and magnetic energy is dissipated very rapidly. Alternatively, plasma microturbulence may develop when the current density in the sheet becomes large enough for current-induced microinstabilities to take place, as in the magnetic field reconnection experiment of Baum et al (1973). However, the details of the trigger which converts a quiet neutral sheet into an active one are not yet clear.…”

Section: Resultsmentioning

confidence: 99%

Preflare current sheets in the solar atmosphere

Priest

Raadu

1975

Sol Phys

View full text Add to dashboard Cite

Neutral current sheets are expected to form in the solar atmosphere when photospheric motions or the emergence of new magnetic flux causes oppositely directed magnetic fields to he pressed together. Magnetic energy may thus be stored slowly in excess of the minimum energy associated with a purely potential field and released suddenly during a solar flare. For simplicity, we investigate the neutral sheet which forms between two parallel line dipoles when either the distance between them decreases or their dipole moments increase. It is found that, when the dipoles have approached by an amount equal to a tenth of their original separation distance, the stored energy is comparable with that released in a major flare. In addition, a similarity solution for one-dimensional magnetohydrodynamic flow within such a neutral sheet is presented; it demonstrates that rapid conversion of magnetic energy into heat is possible provided conditions at the edge of the neutral sheet are changing sufficiently quickly.

show abstract

Section: Resultsmentioning

confidence: 99%

Preflare current sheets in the solar atmosphere

Priest

Raadu

1975

Sol Phys

View full text Add to dashboard Cite

show abstract

“…Until now, experimental observation of spontaneous reconnection has been limited to linear devices [11][12][13], which all include strong three dimensional (3D) reconnection dynamics. Meanwhile, space observations show that the spatial scale along reconnecting current sheets can be several orders of magnitude (10 4 ) larger than the spatial scale perpendicular to the current sheets [14], implying that reconnection in nature can also occur in systems for which the global structure is mostly two dimensional.…”

mentioning

confidence: 99%

Laboratory Observations of Spontaneous Magnetic Reconnection

et al. 2007

View full text Add to dashboard Cite

Detailed measurements of spontaneous magnetic reconnection are presented. The experimental data, which were obtained in the new closed Versatile Toroidal Facility magnetic configuration, document the profile evolution of the plasma density, magnetic flux function, reconnection rate, and the current density during a spontaneous reconnection event in the presence of a strong guide magnetic field. The reconnection process is at first slow, which allows magnetic stress to build in the system while the current channel becomes increasingly narrow and intense. The onset of a fast reconnection event occurs as the width of the current channel approaches the ion-sound-Larmor radius rho s. During the reconnection event magnetically stored energy is channeled into energetic ion outflows and a rapid increase in the electron temperature.

show abstract

“…The presence of space charge fields has important implications on plasma resistivity and dissipation. For example, it explains, in part, the discrepancy between the frequently quoted high plasma resistivity calculated from the induced field alone [Baum et al, 1973] and the low electron heating observed. Space charge electric fields are also crucial to the acceleration of particles and explain partially the highly inhomogeneous ion flows and electron currents observed.…”

Section: Discussionmentioning

confidence: 98%

Magnetic field line reconnection experiments 2. Plasma parameters

Gekelman¹,

Stenzel²

1981

J. Geophys. Res.

View full text Add to dashboard Cite

Detailed measurements of density, temperature, and potentials of a laboratory plasma undergoing magnetic field line reconnection are reported. The plasma column (n ≃1012 cm−3, Te ≃5 eV, B0 ≃20 G) is subject to a time‐varying transverse magnetic field with X‐type neutral point (B⊥max ≃100 G, Δt ≃100 µs). Time‐ and space‐resolved probe measurements show rapid electron heating giving rise to further ionization up to neutral burnout. Density and temperature exhibit strong spatial nonuniformities in all directions as well as significant temporal fluctuations. The plasma potential increases in the direction of the induced electric field, indicating the presence of axial space charge separation. Electrostatic fields also develop perpendicular to the applied fields and can exceed the latter in magnitude. The knowledge of the basic plasma parameters is essential in explaining the observed magnetic field configurations, plasma flows, and resistivity, which are described separately.

show abstract

Plasma instability at an X-type magnetic neutral point

Cited by 40 publications

References 12 publications

Preflare current sheets in the solar atmosphere

Preflare current sheets in the solar atmosphere

Laboratory Observations of Spontaneous Magnetic Reconnection

Magnetic field line reconnection experiments 2. Plasma parameters

Contact Info

Product

Resources

About