Collisionless Shocks in Plasmas

Friedman, Herbert W.; Linson, Lewis M.; Patrick, R.M.; Petschek, H. E.

doi:10.1146/annurev.fl.03.010171.000431

Cited by 20 publications

(7 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…If the combination of shock movement and rocking proposed in this paper to explain the bilateral sequence of shock observations is correct, it appears that in this example most of the shock structure at Explorer 33 was manifested as a wave train extending upstream from the major field gradient. Such a profile is expected for collisionless oblique shocks [Robson, 1969;Friedman et al, 1970]. The dawn shock structure was apparently dominated by low-frequency dispersion, whereas the dusk shock structure was evidently determined by either sufiqciently high dissipation or by high-frequency wave dispersion [Fredricks et al, 1970], or by both, to produce a monotonic transition.…”

Section: Interplanetary Field Orientation a Uniformmentioning

confidence: 89%

“…The local structure of a magnetized collisionless plasma shock depends on the ratio fl of plasma thermal energy to field energy, Alfv•n Mach number M•, and the angle a between the field and the direction of shock propagation [Kennel and Sagdeev, 1967;Paul, 1969;Robson, 1969;Friedman et al, 1970;Coroniti, 1970]. To a magnetometer passing through such a shock, the large-scale or macroscopic structure of the shock appears as a monotonic rise in field, with or without an upstream 'foot,' a double shock, a step rise with a precursor pulse, a series of upstream or downstream waves of various amplitudes and damping distances, or composites of these features depending on the prevailing combination of parameters •, M•, and a.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Observation of nonuniform structure of the Earth's bow shock correlated with interplanetary field orientation

Greenstadt

1972

J. Geophys. Res.

View full text Add to dashboard Cite

Explorer 33 and 35 magnetometers, on the western and eastern flanks of the earth's bow shock, respectively, observed the boundary concurrently between 0130 and 0430 UT, October 30, 1968. Contrasting shock structures were recorded. Explorer 35 saw a quiet abrupt shock, whereas Explorer 33 saw an irregular noisy boundary with much upstream wave activity. The interplanetary field was roughly in the average archimedean spiral angle and was therefore approximately tangent to the shock at Explorer 35 and normal to the shock at Explorer 33. Gross motions and variable tilting of the aberrated shock probably contributed to the peculiar sequence of shock crossings at the two spacecraft. The observations support a model of the shock in which perpendicular and oblique collisionless structures coexist and form a nonuniform magnetosheath outer boundary.

show abstract

Section: Interplanetary Field Orientation a Uniformmentioning

confidence: 89%

mentioning

confidence: 99%

Observation of nonuniform structure of the Earth's bow shock correlated with interplanetary field orientation

Greenstadt

1972

J. Geophys. Res.

View full text Add to dashboard Cite

show abstract

“…The plasma waves producing these interactions and instabilities affect ions and electrons differently due to the large difference in mass (for a review, see e.g. Tidman & Krall 1971; Friedman et al 1971). We might therefore expect to find an electron heating rate shorter than the Coulomb collisional time‐scale behind a cluster merger shock.…”

Section: The Shock Frontsmentioning

confidence: 99%

Shock fronts, electron-ion equilibration and intracluster medium transport processes in the merging cluster Abell 2146

Russell¹,

McNamara²,

Sanders³

et al. 2012

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

We present a new 400-ks Chandra X-ray observation of the merging galaxy cluster Abell 2146. This deep observation reveals detailed structure associated with the major merger event including the Mach number M = 2.3 ± 0.2 bow shock ahead of the dense, ram pressure stripped subcluster core and the first known example of an upstream shock in the intracluster medium (ICM) (M = 1.6 ± 0.1). By measuring the electron temperature profile behind each shock front, we determine the time-scale for the electron population to thermally equilibrate with the shock-heated ions. We find that the temperature profile behind the bow shock is consistent with the time-scale for Coulomb collisional equilibration and the post-shock temperature is lower than expected for instant shock heating of the electrons. Although like the Bullet cluster the electron temperatures behind the upstream shock front are hotter than expected, favouring the instant heating model, the uncertainty on the temperature values is greater here and there is significant substructure complicating the interpretation. We also measured the width of each shock front and the contact discontinuity on the leading edge of the subcluster core to investigate the suppression of transport processes in the ICM. The upstream shock is ∼440 kpc in length but appears remarkably narrow over this distance with a best-fitting width of only 6 +5 −3 kpc compared with the mean free path of 23 ± 5 kpc. The leading edge of the subcluster core is also narrow with an upper limit on the width of only 2 kpc separating the cool, multiphase gas at 0.5-2 keV from the shock-heated surrounding ICM at ∼6 keV. The strong suppression of diffusion and conduction across this edge suggests a magnetic draping layer may have formed around the subcluster core. The deep Chandra observation has also revealed a cool, dense plume of material extending ∼170 kpc perpendicular to the merger axis, which is likely to be the disrupted remnant of the primary cluster core. This asymmetry in the cluster morphology indicates the merger has a non-zero impact parameter. We suggest that this also explains why the south-western edge of the subcluster core is narrow and stable over ∼150 kpc in length, but the north-eastern edge is broad and being stripped of material.

show abstract

“…He demonstrated particularly clearly the physical ideas of dispersive shock wave formation and the onset of dissipation and advertised the method of the later-so called Sagdeev potential.This first seminal paper led the foundation for a three decade long fruitful research in nonlinear wave structures and shock waves. [144] This extraordinarily important step was followed by the next early period that was represented by the review papers of [46], [131], [12], [50], [44], [57], again [117] and ultimately two large review volumes edited by [127] and [132].…”

Section: E Three Decades Of Exploration: Theory and Observationmentioning

confidence: 99%

Fundamentals of Non-relativistic Collisionless Shock Physics: I. The Shock Problem

Treumann,

Jaroschek

2008

Preprint

View full text Add to dashboard Cite

The problem of collisionless shocks is posed as the problem of understanding how in a completely collisionless streaming high-temperature plasma shocks can develop at all, forming discontinuous transition layers of thickness much less than any collisional mean free path length. The history of shock research is briefly reviewed. It is expressed that collisionless shocks as a realistic possibility of a state of matter have been realized not earlier than roughly half a centruy ago. The basic properties of collisionless shocks are noted in preparing the theory of collisionless shocks and a classification of shocks is given in terms of their physical properties, which is developed in the following chapters. The structure of this chapter is as follows: 1. A cursory historical overview, describing the early history, gasdynamic shocks, the realisation of the existence of collisionless shocks and their investigation over three decades in theory and observation until the numerical simulation age, 2. Posing the shock problem as the question: When are shocks? 3. Types of collisionless shocks, describing electrostatic shocks, magnetized shocks, MHD shocks, shock evolutionarity and coplanarity, switch-on and switch-off shocks, 4. Criticality, describing the transition from subcritical dissipative to supercritical viscose shocks, 5. Remarks.

show abstract

Collisionless Shocks in Plasmas

Cited by 20 publications

References 13 publications

Observation of nonuniform structure of the Earth's bow shock correlated with interplanetary field orientation

Observation of nonuniform structure of the Earth's bow shock correlated with interplanetary field orientation

Shock fronts, electron-ion equilibration and intracluster medium transport processes in the merging cluster Abell 2146

Fundamentals of Non-relativistic Collisionless Shock Physics: I. The Shock Problem

Contact Info

Product

Resources

About