Eric Walker wrote: > On Thu, Jan 16, 2014 at 8:55 AM, <[email protected]> wrote: > >>Yes. Once established the large current densities generate huge magnetic >> fields circulating the current flow, or equivalently a magnetic vector >> potential field pointing in current flow direction. If the current >> suddenly stops, oppositely charged particles oppositely moving in the >> plasma flow collide in energetic "compressions." ... > > Something along these lines is the horse I'm currently betting on. I > would not be surprised if at the nano level you could get electric and > magnetic fields that far surpass what we currently produce in the > strongest accelerators, electromagnets and magnetic confinement fusion > reactors. The absolute magnitudes may be minuscule, but the electric > and magnetic fluxes could be off charts. For a little wisp of a thing > like a proton, the forces could be sufficient to do whatever you want > them to do.
Eric, you might find it interesting that temperatures approaching those in stellar centers can be created with low laser energies impinging on nanowire arrays - in a small desktop experiment. See - "Relativistic plasma nanophotonics for ultrahigh energy density physics" http://www.nature.com/nphoton/journal/v7/n10/full/nphoton.2013.217.html -- which ends with the statement: "We obtained extraordinarily high degrees of ionization (for example, 52 times ionized Au) and gigabar pressures only exceeded in the central hot spot of highly compressed thermonuclear fusion plasmas. Scaling to higher laser intensities promises to create plasmas with temperatures and pressures approaching those in the centre of the Sun." This experiment generates immense electric field gradients. Also see - "Hairy metal laser show produces bright X-Rays" -- Setting metallic wires on fire creates a bright X-Ray glow http://arstechnica.com/science/2013/11/hairy-metal-laser-show-produces-bright-x-rays/ "Plasma from 'hairy' target releases high-energy x rays" http://scitation.aip.org/content/aip/magazine/physicstoday/news/news-picks/plasma-from--hairy--target-releases-high-energy-x-rays-a-news-pick-post > My graphic is alluding to what you're getting at: > > http://i.imgur.com/PoRGR7G.png Yes. You might want to include the magnetic vector potential in your graphic which points in the same direction as the current density vector "I" - it is proportional to the field momentum each unit charge will acquire when the current is interrupted. Note that the momenta will be in opposite direction for positive vs. negative charges - forcing collisions, or "compressions" between them. > In this case, there's a momentary compression of protons within a lattice > defect as a spark crosses a gap between two electrically insulated grains > in the metal. The magnetic field confines them to the axis of travel of > the spark, and they migrate under the influence of a very strong potential > towards the far end of the lattice defect, where they clump up. If there > are deuterons in there, you could get 3He. But even if there are none, > the protons could be compressed into the lattice sites themselves, > provided the whole thing happens faster than a dislocation. > >> It would be interesting to quantify the momentum/energy impulses charged >> particles around the currents receive. > > I would love to see some back-of-the-envelope calculations for the forces > that could be generated. I want to do that for the nanoring example of the paper - "Optical generation of intense ultrashort magnetic pulses at the nanoscale" http://arxiv.org/pdf/1303.6072v1.pdf The math for a nanoring is simpler than for a straight current arc since it is a complete circuit, and doesn't require too many approximations. -- LP
