parabolic beams of electrons

[happyjack27]

http://arstechnica.com/science/2013/02/ ... -barriers/

[DeltaV]

I have to wonder how this might relate to Ardavan's Polarization Synchrotron with its spirally-propagating wavefronts.

[ladajo]

Was there not follow on work that disproved the spiraling?
Now I gone and done it. I said it. So now I have to go look for it...
poop.

[DeltaV]

Looks to me like Polarization Synchrotron theory and experiment are in agreement --

Experimental demonstration of a new radiation mechanism: emission by an oscillating, accelerated, superluminal polarization current

The excellent correspondence between the experimental data and theoretical predictions supports the proposal that
polarization current distributions act as superluminal sources of radiation, and that they can be used for studying
and utilizing the novel effects associated with superluminal electrodynamics. The apparatus described in this paper
represents just one possible geometry and excitation scheme. In principle, a whole class of superluminal sources are
possible, corresponding, for example, to a rectilinearly accelerated polarization current [6] (rather than a centripetally
accelerated one), or to a medium that is polarized by impinging laser beams (rather than by applied voltages), and
so on. It is hoped that the publication of this paper will stimulate further work along these lines.

Experimental demonstration of emission from a superluminal polarization current- a new class of solid-state source for MHz-THz and beyond

The cusp and circumvention of inverse square decay

As mentioned above, the radiation emitted from each volume
element of the PS comprises a Cerenkov-like envelope; this
possesses two sheets that meet along a cusp [1-3]. These cusps
spiral upwards and outwards from the source, and each
represents the locus of observation points that a given source
element approaches with the speed of light and with zero
acceleration at various emission times [I-31. This results in the
detection over a short observation time period of radiation
emitted over a considerably longer period of source time.
Consequently, the intensity of the radiation in the direction of
these cusps will decline more slowly with increasing distance
from the source than would the emission from a conventional
antenna [2,3]. Note, however, that energy conservation is not
violated; large intensities on the cusp are compensated by
weaker radiation fields elsewhere; the propagating cusp is
being constantly reconstructed from conventional (i.e.
spherically-decaying) waves that combine and then disperse.

OK, the cusps are spirally-propagating, not the wavefronts.

[ladajo]

Here is some of what I was recalling...

Pro:
http://iopscience.iop.org/1367-2630/14/11/118002

Con:
http://iopscience.iop.org/1367-2630/14/11/118001

http://ieeexplore.ieee.org/xpl/articleD ... er=6059486

http://www.plosone.org/article/info:doi ... ne.0056086

[DeltaV]

The OAM stuff you linked is a different concept from Ardavan's Polarization Synchrotron.