Z-pinches, stellar jets and star formation

[hertz]

While looking around, trying to figure out whatever happened to plasma physics in astrophysics I came across one
Andrea Ciardi, Maître de Conférences - Lecturer, Université Pierre et Marie Curie and his homepage:
http://amrel.obspm.fr/ciardi/index.html

On his homepage Andrea notes:

I am interested in both laboratory and astrophysical plasmas, in particular the dense plasmas produced on Z-pinches and laser installations to study astrophysical phenomena connected to star formation and their environment

His publications page is a veritable motherload of Z-pinch research, most of which is available via arXiv. It's going to take awhile to get through it all but a quick look produced the following examples:

http://arxiv.org/PS_cache/arxiv/pdf/090 ... 0268v1.pdf

Considering that most of the experiments, both on laser and on z-pinches, are less than 10 years old, it should not come as a surprise that in many instances the applications to astrophysics are not yet fully developed or very clear.

http://arxiv.org/abs/1009.0453

The ejection of plasma in the form of more or less collimated bi-polar flows (jets) is arguably one of the most spectacular displays staged by a forming star. Over a million years, these outflows trace the creation of stars from their embryonic emergence as proto-stars, still enveloped in their dense parental cloud, to their birth as T Tauri stars surrounded by proto-planetary discs.

http://arxiv.org/abs/0909.3190
Disk formation during collapse of magnetized protostellar cores

There is also a great presentation on jets and young stars here with very informative diagrams etc:
http://www.luli.polytechnique.fr/pages/ ... ciardi.pdf

[Osmosis]

A wonderful find, hertz!
Osmosis

[hertz]

first time i've ever seen accretion linked to ejection and clumpiness, that's for sure

http://arxiv.org/PS_cache/arxiv/pdf/100 ... 0453v2.pdf

The results show that with increasing misalignment, the general trend of mass ejection-accretion in collapsing pre-stellar cores is to produce higher mass adiabatic cores, with lower ejection efficiency...Scaled laboratory astrophysics experiments of compressible, super-magnetosonic MHD flows have also shown that although jets may be episodic and unstable, multiple ejections of magnetic cavities and jets can produce clumpy flows which remain well collimated.

think he's onto something

link on the hompage to xla conference (http://amrel.obspm.fr/ciardi/xla/) is also awesome...lebedev preso (9MB) is an eye opener...not surprisingly, under Future Work, "Close interaction with the astrophysics community is needed" is noted as "most important"...lol

[hertz]

almost missed this bit:

The results show the system evolving into a structure consisting of an approximately cylindrical magnetic cavity with an embedded jet on its axis confined by the magnetic "pinching" force. A shell of swept-up plasma surrounds and partially confines the magnetic bubble. The subsequent evolution is dominated by current-driven instabilities and the development of the asymmetric "kink" mode (m = 1) which leads to a distortion of the jet and a re-arrangement of the magnetic field.

Magnetically driven jets from radial wire arrays
http://arxiv.org/PS_cache/arxiv/pdf/090 ... 0268v1.pdf

[hertz]

another interesting simulation published about a year ago

http://plasma.physics.ucla.edu/papers/T ... 075005.pdf

Laboratory Simulation of Arched Magnetic Flux Rope Eruptions in the Solar Atmosphere
S. K. P. Tripathi and W. Gekelman
Physics and Astronomy, University of California at Los Angeles, Los Angeles, California 90095, USA
(Received 9 February 2010; published 13 August 2010)

Our measurements have identified critical changes associated with the eruption, namely, the outward expansion of the AMFR (arched magnetic flux rope), development of a large twist in its magnetic field, release of the AMFR plasma, and excitation of the fast wave. Observation of the fast wave is particularly important since fast waves can transport energy across magnetic field lines (unlike shear Alfven waves), efficiently carry energy flux, and exist at frequencies higher than the cyclotron frequency. These unique features make the fast wave a potential candidate for coronal heating. Recent spacecraft observations have also revealed that flows and intense magnetosonic waves coexist in the solar AMFRs. Such magnetosonic waves are estimated to contain sufficient energy to heat the AMFR to the coronal temperatures.

[jjohnson]

Currently there is increasingly useful work being done again at Los Alamos National Labs and Princeton Plasma Physics Laboratory. Philipp Kronberg at Los Alamos and the University of Toronto is a real contributor - here is his (and 3 other authors') arXiv paper on the measurement of current in a kiloparsec scale galactic jet.

[hertz]

thanks jim, it was this kronberg paper that kind of got me going down this path...if i'm not mistaken, this paper was the one that started the "largest electric current found" thread a few weeks back, at which time everybody got all hot and bothered about the "b" word (blackhole) and got me wondering why kronberg et al. either couldn't or wouldn't call a spade a spade, i.e. z-pinch...

i mean to me, blackholes are so obviously z-pinches (and i can already hear nereid asking what's so obvious about it...lol...kinda miss her actually) that i figured there had to be some historic or cultural taboo associated with its use and which is one of the reasons i was so excited to find the work of lebedev, ciardi et al. who are unabashedly drawing the link between z-pinches and astrophysical jets (although they too label some of their diagrams with a "blackhole" at the center of the z-pinch where the plasma originates...perhaps to appease the reviewers?)

at this point i can only guess that z-pinches are most commonly associated with fusion research and as such somehow still outside the realm of mainstream astrophysics either by design (perhaps blackholes will pass away when hawking does) or through ignorance of their existence (my guess)...nevertheless, if we put the two together: kronberg's electric currents and ciardi's z-pinches, i think we'll see that EU theory is slowly (ever so slowly) but surely making its way into the mainstream...keep the faith, eh

[jjohnson]

Yes, keep the faith, but pass the ammunition!

Kronberg says he'll have the final version up on arXiv in a few weeks. I like and respect his work. Just ignore the BH parts - the rest is good science.

Actually some of the current textbooks (plasma physics fundamentals type) do discuss z-pinches. They almost never go into the cosmic implications in any detail, however. Boris Somov's Fundamentals of Cosmic Electrodynamics is pretty good, although he devotes a lot of time to magnetic reconnection. Other than Peratt's book, out of print and generally unaffordable, Paul Bellan's Fundamentals of Plasma Physics is good if you don't mind math. He comments on a wide variety of disciplines in which plasma physics is applicable, including space plasmas, but like most authors he doesn't get much into those applications. But if you go to his website you'll see photos of his solar filament plasma experiments and other fun stuff.

Enjoy learning this stuff! I know I do, and have a long way to go.