Crossfire Fusion

[MTd2]

http://www.crossfirefusion.com/nuclear-fusion-reactor/overview.html

A project of a guy from my country.

[Rezwan]

Thanks MTd2,

I’ve started this new thread for Crossfire. What do you know about them?

[MTd2]

Nothing really. I just stumbled on that on wikipedia. I am still trying to figure out his idea. But there are cool animations on his website! 😀

[mjv1121]

i’ve had my eye on this website for a while too – admittedly mostly for the cool animations. i have to admit though that his explanation of the process beyond my meagre understanding. there was one red flag that caught my eye – he stipulates that “fuel must be injected in small quantities in order to prevent uncontrolled magnetic reconnection” – i don’t think this should be much of a problem seeing as there is no such thing as magnetic reconnection!

[zapkitty]

mjv1121 wrote: … he stipulates that “fuel must be injected in small quantities in order to prevent uncontrolled magnetic reconnection” – i don’t think this should be much of a problem seeing as there is no such thing as magnetic reconnection!

Is there a magnetic reconnection conspiracy?… 🙂

[jamesr]

zapkitty wrote:

… he stipulates that “fuel must be injected in small quantities in order to prevent uncontrolled magnetic reconnection” – i don’t think this should be much of a problem seeing as there is no such thing as magnetic reconnection!

Is there a magnetic reconnection conspiracy?… 🙂

The simple MHD fluid models do not fit observations of reconnection very well (for example in the tail of Earth’s magnetosphere causing bursts in auroral activity).
But newer extended Hall & two-fluid models are much closer. To fully capture the dynamics of reconnection you need a fully kinetic simulation, that can cope will relativistic electrons. Which some 2D computer simulations can now do for simple scenarios, but large full 3D ones are still a few years away.

If you want to see some simple animations of magnetic reconnection have a look at:
http://www.astro.virginia.edu/VITA/ATHENA/cs.html

[mjv1121]

Definitely!. There is absolutely a magnetic reconnection conspiracy. Magnetic reconnection, very much like the big bang, did not happen!!!!! There is no such thing as magnetic field lines. Magnetic field lines DO NOT EXIST.

[jamesr]

Of course the ‘Lines’ our just our way of plotting contours on a graph, much like meteorologists plot isobars on a weather map. On a weather map, the topology of the isobar lines can change as areas of high or low pressure merge. When we talk about magnetic reconnection it is the lines on our magnetic map that ‘reconnect’.

However it does have a very real and physical consequence…. Since ions and especially electrons are “frozen” in to follow the direction of the magnetic field, gyrating around in a helical motion, they are confined to that topological region of space.

Using the astrophysical example again; an electron caught in Earths magnetosphere must remain in Earth’s magnetosphere. Similarly an electron in the Solar wind is confined to the Sun’s Heliosphere. When they connect, on occasion, in the tail, ions and electrons from the solar wind can pass into the Earths magnetosphere, where they stream down the field towards the poles hitting the upper atmosphere causing the aurora.

[mjv1121]

“There is no ‘field-line reconnection’ that can transfer energy to the particles, nor release energy in any other way.” – Hannes Alfven 1976

…I have found an excellent page: http://sites.google.com/site/cosmologyquest/what-we-do-know/magnetic-reconnection

However, back to crossfire. My point was that if he mentions magnetic reconnection (which does not exist) raises a certain doubt.
Mind you, it would be fantastic as spacecraft propulsion if it worked. I still favour Focus Fusion for terrestrial power generation – its mechanical simplicity and small size are an enormous advantage.

[jamesr]

mjv1121 wrote: “There is no ‘field-line reconnection’ that can transfer energy to the particles, nor release energy in any other way.” – Hannes Alfven 1976

…I have found an excellent page: http://sites.google.com/site/cosmologyquest/what-we-do-know/magnetic-reconnection

I beg to differ. That page is woefully out of date and misleading. Much work has been done in this area in the past few years and although not complete, our understanding of magnetic reconnection and assosiated energy release has moved on a lot since most of the papers cited on that website.

Here are just a few from a quick search:
A. Lazarian, G. Kowal, E. Vishniac, E. de Gouveia Dal Pino, Fast magnetic reconnection and energetic particle acceleration, Planetary and Space Science, In Press, Corrected Proof, Available online 22 July 2010, ISSN 0032-0633, DOI: 10.1016/j.pss.2010.07.020.
(http://www.sciencedirect.com/science/article/B6V6T-50KRYSG-2/2/ffd72a4b4edea898faa7379860361f3b)
Abstract:
Our numerical simulations show that the reconnection of magnetic field becomes fast in the presence of weak turbulence in the way consistent with the Lazarian and Vishniac (1999) model of fast reconnection. We trace particles within our numerical simulations and show that the particles can be efficiently accelerated via the first order Fermi acceleration. We discuss the acceleration arising from reconnection as a possible origin of the anomalous cosmic rays measured by Voyagers.

D.I. Pontin, Three-dimensional magnetic reconnection regimes: A review, Advances in Space Research, In Press, Accepted Manuscript, Available online 8 January 2011, ISSN 0273-1177, DOI: 10.1016/j.asr.2010.12.022.
(http://www.sciencedirect.com/science/article/B6V3S-51WV08G-2/2/325d6bef0a412cf8b82c51c436272364)
Abstract:
The magnetic field in many astrophysical plasmas – such as the Solar corona and Earth’s magnetosphere – has been shown to have a highly complex, three-dimensional structure. Recent advances in theory and computational simulations have shown that reconnection in these fields also has a three-dimensional nature, in contrast to the widely used two-dimensional (or 2.5-dimensional) models. Here we discuss the underlying theory of three-dimensional magnetic reconnection. We also review a selection of new models that illustrate the current state of the art, as well as highlighting the complexity of energy release processes mediated by reconnection in complicated three-dimensional magnetic fields.
Keywords: magnetic fields; magnetic reconnection; magnetohydrodynamics

M. Barta, J. Buchner, M. Karlicky, Multi-scale MHD approach to the current sheet filamentation in solar coronal reconnection, Advances in Space Research, Volume 45, Issue 1, 4 January 2010, Pages 10-17, ISSN 0273-1177, DOI: 10.1016/j.asr.2009.07.025.
(http://www.sciencedirect.com/science/article/B6V3S-4WXC26D-2/2/f28974a02cc3636b72bfc0ccef3f6562)
Abstract:
Magnetic field reconnection – considered now as a key process in the commonly accepted standard scenario of solar flares – spans over many mutually coupled scales from the global flare dimensions ([approximate]10 Mm) down to the scale, where non-ideal kinetic plasma effects takes place ([approximate]10 m). Direct numerical simulation covering all the scales is, therefore, impossible. Nevertheless, the filamentary nature of the current sheet fragmentation together with rescalability of ideal-MHD equations – which governs the processes before reaching the scales of non-ideal plasma response – allow to describe the large- and intermediate-scale dynamics of reconnection flow with highly reduced request for number of grid points. Since the smaller-scale (and faster) dynamics sets-in only in regions of enhanced current sheet filamentation, we focus just on these areas, which occupy only a small fraction of the total volume. Generally, as the fragmentation continues, it forms a cascade of filamentation until kinetic non-ideal processes come to play. Information relevant for description of the smaller-scale physics occupies only a small fraction of grid-cells describing the large-scale dynamics. Thus, one can subsequently zoom-in onto the regions of continuing current filamentation. The current-sheet fragmentation cascade anticipated by Shibata and Tanuma [Shibata, K., Tanuma, S. Plasmoid-induced-reconnection and fractal reconnection. Earth, Planets, and Space 53, 473-482, 2001], creates multiple dissipative regions in a single current sheet, which can play a key role for DC-field particle acceleration in a flare reconnection. The main goal of the paper is to numerically investigate the relevance of cascading reconnection for solar flares. The numerical algorithm implemented for that purpose and first results are presented in this research note. Proposed algorithm – though motivated by the self-similar nature of MHD equations – belongs in fact to the class of block-structured Adaptive Mesh Refinement codes.
Keywords: Solar flares; Magnetic reconnection; Numerical MHD

[mjv1121]

Clearly there is a difference of opinion, even within plasma physics community, and I must concede that the consensus view is to accept that reconnection is a genuine process. I choose to believe that it is a misinterpretation of current effects in plasma. I don’t think either of us is likely to convince the other, so shall we agree to differ, or shall we stamp our feet and shout louder?

[vansig]

and here i thought that a magnetic field line was a virtual path through the solution space of a system of differential equations, forming a hamiltonian cycle.
but i actually have very little knowledge of them.

[mjv1121]

if you start following solution space paths thru differential equations you’re almost certain to get lost, even if you’re on a pretend Scottish bicycle

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