modeling astrophysical phenomena with dense plasma focuses

[wolfram]

So I’m doing this final project for a plasma seminar class and I was thinking about doing a literature review of how dense plasma foci are used to model astrophysical systems. I’d do it on fusion proper but it’s an astrophysical plasmas class, so I’m just shooting for awareness raising in the faculty around here at Iowa. I’m presented with a problem, most of the searches I do produce articles that are either about power production (here), or only tangentially related ( the most interesting one that i’ll read later is on solid-density plasmas). The closest I’ve gotten is from an iranian physicist that asserts that black holes aren’t real, not just bizarrely non-physical.

I throw myself at the masses, are there any instances of using a DPF for astronomy research, like field aligned currents or accretion discs?

[asymmetric_implosion]

I’m sitting at the High energy density laboratory astrophysics conference so I found your post funny. No one I know of uses PF devices for so called lab astro problems. The closest thing I know of is using modified Z-pinch to model jets formed by various bodies and colliding them with gas jets or gas blankets. Look up experiments on the MAGPIE generator by Sergey Lebedev and his group if you want to go this route. They started this work a few years back and in my opinion are still the best physicists working the problem.

[wolfram]

I thank you for the suggestion, lament at your observation that this is a small field of research, and find it interesting how many lebedev’s have published to arxiv.

[Lerner]

well, it was a DPF-based model of qusaars by me that got this whole proejct started back inthe ’80’s

[jamesr]

There was an interesting talk by Francisco Suzuki-Vidal from the MAGPIE group at the IOP conference last month about radiatively cooled plasma jets, and I was wondering how good their GORGON MHD code would be at modelling a DPF (the initial phases of snowplow, shock, rebound etc, not the plasmoid)

This is the paper that goes with it – http://pop.aip.org/resource/1/phpaen/v19/i2/p022708_s1

[asymmetric_implosion]

Gorgon can model a PF until you reach the implosion. It is, in principle, no better than any of the other large lab codes. Gorgon has been used on Z-pinches for some time now at Imperial College and more recently at Sandia. My group submitted a proposal to DOE to work with the Imperial College guys to model the PF adding onto Gorgon so it can model the pinch using PIC methods, but I don’t think the funding folks are behind it based upon the latest feedback. PF is too “well known” to be worth studying at the 5 MA) is too uncertain. All in all it is the view of DOE reviewers that PF isn’t going to work for the problems of interest for DOE/NNSA. NIF is the only cathedral anyone cares about right now. If your experiments are not supporting NIF and/or not scalable to NIF then please see the door. I have to hand it to Livermore; they marketed NIF beautifully at DOE and around the world. At the HEDLA meeting everyone was buzzing about NIF and what it will do. To be fair, they have done some amazing things with radiative shocks and extremely high pressure compression at low temperature. My primary concern is the cost. NIF cost like $4B while a pulse power machine costs more like $40M.

[jjohnson]

Using moons of gas giant planets could be an interesting way of putting focused plasma phenomena together with real life data, photos and observations, as well as a lot of papers, on charged bodies that move within the magnetospheres and plasma toruses (I don’t like ‘torii’), creating polar electric currents that close the circuit between moon and planet, light up the atmospheric gases in the auroral ovals, and produce electric discharge machining and Joule heating via telluric currents at the moons’ discharge locales.

Peratt’s text, Physics of the Plasma Universe, Springer Verlag, 1992, in discussing domains of cosmic plasmas, in 1.2.3 Plasmas in the Solar System, discussed the magnetospheres around Jupiter and Saturn well before Cassini visited Saturn. The Jupiter-Io plasma torus is discussed. In Chapter 4, Electric Fields in Cosmic Plasma, 4.6.2 Plasma Gun Arc Discharges is pertinent and useful to someone who knows little about how a dense plasma focus is created. It is well documented and referenced with good diagrams and photos. This phenomenon is then presented in Example 4.1 Electric Arcs on the Jovian satellite, Io, with worked examples of the electric field due to the co-rotation of its plasma torus. Illustrations of Prometheus’s plume, both obliquely from above and silhouetted above Io’s limb, noting that the current flow is outward from “volcano” or the vent known as Prometheus – i.e., Prometheus is an anode.

Cassini’s observations of Enceladus and its “icy geysers” around the south pole region, and just as important, its measurements of a “magnetic flux tube” constituting the northern half of the electric circuit between this little moon and Saturn’s northern auroral oval (with “hot spots” or “footprints” seen in X-ray light where the flux tube isincident upon the planet. Anomalously warm temperatures were reported around the “Tiger Stripes” near Enceladus’s south pole. While some papers have argued for tidal heating, that appears to be a stretch becasue the predicted heating by that method was found to be far less than actual, so the exploration of Joule heating via telluric or sub-surface electric current flows should at least be considered as a reasonable heating explanation, given the failure of the tidal heating hypothesis. Even today, Carolyn Porco is characterizing Enceladus’s ionized discharge as consisting of icy particles, water vapor and molecules”, when in fact it is all this matter in an ionized state, as the plasma instrumentation has clearly recorded.

The outer 2 gas giants also have active magnetospheres, polar aurors and unusual activity photographed on their moons’ surfaces by the Voyager spacecraft as it flew by. Very little else has been measured out there, due to deficiencies in budget and the extreme range represented by these planets. Neptune is 4 and a quarter light hours out. I think an interesting case study of any of these might be a good intro to plasma dense focus phenomena and real life applicability to a series of electrical events right here in our solar system, with on-going studies by NASA and ESA. Best of luck with your project.

Jim

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