Field-generating thermal instability in laser-heated plasmas

Tidman, D. A.

doi:10.1063/1.1694866

Cited by 187 publications

(88 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…∇n e = 0, precluding ∇T e × ∇n e field generation), nor hydrodynamic motion or anisotropic pressure. Thus, what we see is distinct from instabilities existing in the literature: such as those of Tidman-Shanny [12][13][14], for which ∇T e × ∇n e is necessarily non-zero; Weibel [15], where magnetic fields are not essential; Haines [16,17], which does not require either Righi-Leduc heat-flow or the Nernst effect; and Davies [18], where unstable filamentation arises from plasma motion.In our case, terms responsible for growth go as k 3 2 , where k is the wavenumber of a perturbation (not the more usual k), yielding traveling waves rather than purely growing perturbations. These, however, differ from the thermal-magnetic waves described by Pert [19] who neglected the Nernst effect.…”

mentioning

confidence: 76%

Field Compressing Magnetothermal Instability in Laser Plasmas

2010

View full text Add to dashboard Cite

The mechanism for a new instability in magnetized plasmas is presented and a dispersion relation derived. Unstable behaviour is shown to result purely from transport processes -feedback between the Nernst effect and the Righi-Leduc heat-flow phenomena in particular -neither hydrodynamic motion nor density gradients are required. Calculations based on a recent nanosecond laser gas-jet experiment [1] predict growth of magnetic field and temperature perturbations with typical wavelengths of order 50µm and characteristic growth times of ∼0.1ns. The instability yields propagating magneto-thermal waves whose direction depends on the magnitude of the Hall Parameter.PACS numbers: 52.25. Fi, 52.25.Xz, The existence of large self-generated magnetic fields in laser-produced plasmas (∼100T) has long been known [2,3]. These fields can significantly affect the distribution of thermal energy in plasma targets by suppressing the cross-field thermal conductivity [4]. In recent years several experiments have been designed to assess their impact on inertial confinement fusion (ICF) schemes [5] and to study more general magnetic phenomena in laser plasmas, such as magnetic reconnection [6] and instability [7]. In addition, there has been increased discussion of the possible uses for applied magnetic fields in the suppression of non-local transport [1], control of plasma density channels [8], wakefield acceleration [9] and magnetized target fusion (MTF) schemes [10].In this letter we report a new instability shown computationally to impact on magnetized plasmas, though it may also take effect in the presence of self-generated fields. The instability compresses the magnetic field and distorts thermal energy profiles by concentrating the heat-flow (see figure 1), and may be important when a high degree of symmetry or control of heat transport is needed, or where uniform fields are applied for a specific purpose, such as those cases mentioned above [1,[8][9][10].Feedback is driven solely by classical (Braginskii) transport processes [4]: specifically the interaction of the Nernst effect, which describes advection of magnetic field with heat-flow down temperature gradients q ⊥ and with velocity v N ≈ 2q ⊥ /5P e , where P e is the isotropic pressure [11]; and the Righi-Leduc heat-flow, the cross-field thermal-flux 'bent' by magnetic fields acting on negatively charged heat-carrying electrons. Consequently we require only the presence of temperature gradients ∇T e perpendicular to an existing magnetic field for instability. Gradients in electron number density n e are not needed (i.e. ∇n e = 0, precluding ∇T e × ∇n e field generation), nor hydrodynamic motion or anisotropic pressure. Thus, what we see is distinct from instabilities existing in the literature: such as those of Tidman-Shanny [12][13][14], for which ∇T e × ∇n e is necessarily non-zero; Weibel [15], where magnetic fields are not essential; Haines [16,17], which does not require either Righi-Leduc heat-flow or the Nernst effect; and Davies [18], where unstable filamentation ar...

show abstract

mentioning

confidence: 76%

Field Compressing Magnetothermal Instability in Laser Plasmas

2010

View full text Add to dashboard Cite

show abstract

“…In the modeling of the rare-gas media it has been found that the spin-changing collisional processes Xe 2 ( 1 2*) + Xe-Xe 2 ( 3 2*) + Xe (61) and Xe 2 ('£,*)-!• e^Xe 2 ( 3 2,*)+ e~ (62) are essential for a quantitative understanding of these systems. The inclusion of these considerations has produced a refinement in our previously constructed analysis.…”

Section: Theoretical Studies >mentioning

confidence: 99%

Laser-fusion program. Semiannual report, July--December 1973

1974

View full text Add to dashboard Cite

“…heating can suppress growth-rates of one such candidate, the field-generating thermal instability, which was first reported in 1974 (Tidman & Shanny 1974;Bol'shov et al 1974), and remains an important phenomena in laser-plasma interactions (see, for example, experimental studies of coronal plasmas by Manuel et al (2013) reported earlier this year). It is widely held that this instability may be driven by two mechanisms which-denoting the electron temperature and density as T e and n e respectively, and taking b = B/|B| as a unit vector in the direction of the magnetic flux density B-may be summarised as follows.…”

Section: Introductionmentioning

confidence: 99%

“…These fields strongly affect electron transport by suppressing the cross-field thermal conductivity (Braginskii 1965) and are thus key to understanding a range of laser-plasma interactions, including ongoing efforts to achieve controlled inertial confinement fusion (Glenzer et al 1999;Lindl et al 2004;Nilson et al 2006;Froula et al 2007;Li et al 2007a,b;Schurtz et al 2007;Froula et al 2009;Li et al 2009Li et al , 2013. Of special importance in such contexts is the role transport effects might play in driving instabilities, especially given that such instabilities are themselves often candidate mechanisms for producing the self-generated field (Weibel 1959;Tidman & Shanny 1974;Bol'shov et al 1974;Ogasawara et al 1980;Haines 1981;Bissell et al 2010Bissell et al , 2012Gao et al 2012;Manuel et al 2013).…”

Section: Introductionmentioning

confidence: 99%

Nernst advection and the field-generating thermal instability revisited

Bissell

2014

J. Plasma Phys.

View full text Add to dashboard Cite

The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. It is widely held that the Nernst effect can drive instability in un-magnetised laserplasmas by laterally compressing seed B-fields arising from the field-generating thermal instability [Tidman & Shanny, Phys. Fluids, 12:1207]. Indeed, for wavelike perturbations, differential compression by the Nernst mechanism is thought to be most pronounced in the limit of low wave-number k → 0, and is considered particularly important given that it can ostensibly lead to instability when the more usual field-generating mechanism is stable. However, as part of a recent article [Bissell et al., New J. Phys., 15:025017 (2013)] we noted some irregularities to the Nernst mechanism which obscure its operation. For example, by taking characteristic density and temperature length-scales l n and l T respectively, we observed that consistent analytical treatment of the instability requires kl n,T 1, preventing the peak-growth limit k → 0. Furthermore, the Nernst term-which compresses magnetic field perturbations-does not couple to a corresponding term acting on thermal perturbations, and as such does not describe an unstable feedback mechanism. In this article we probe the origin of such ambiguities more formally, and in so doing argue (contrary to reports existing elsewhere in the literature) that the Nernst effect does not drive instability in un-magnetised conditions, at least not in the fashion typically cited.PACS codes: Authors should not enter PACS codes directly on the manuscript, as these must be chosen during the online submission process and will then be added during the typesetting process (see http://www.aip.org/pacs/ for the full list of PACS codes)

show abstract

Field-generating thermal instability in laser-heated plasmas

Cited by 187 publications

References 6 publications

Field Compressing Magnetothermal Instability in Laser Plasmas

Field Compressing Magnetothermal Instability in Laser Plasmas

Laser-fusion program. Semiannual report, July--December 1973

Nernst advection and the field-generating thermal instability revisited

Contact Info

Product

Resources

About