ICCD photos show 150-micron plasmoid, sequence of events in pinch

We are getting high-quality ICCD pictures, thanks to Fred Van Roessel’s work.  The main improvement from early images is a slight shift in angle of view so we are not looking straight horizontally, but rather up at the sheath from a slight angle, which allows us to see things a lot better.  While we did not plan it that way, these four pictures end up as a sequence:

Shot 9-09-10-03, 0.845 microsec before pinch

Shot 9-09-10-02, 0.225 microsec before pinch

Shot 9-15-10-07, at pinch

Shot 9-09-10-05, 0.285 microsec after pinch

There is a lot in these images [which are linked to here to reduce email size], but a few things should be noted.  In shot 9-09-10-03, we can see for the first time with FF-1 the filament pairs.  It looks like there are about 16 pairs, one for each cathode rod, and their filaments are about 200 microns in radius (our resolution right now is about 60 microns).  In shot 9-09-10-02, we see the convergence of current into the pinch region well before the formation of the plasmoid.  The filaments have started to annihilate each other and now there are only four left.  In shot 9-15-10-07, taken exactly at the time of the pinch, we see a plasmoid exactly on axis, greatly magnified here, which is about 150 microns across.  (The small dots are individual ICCD pixels, so do not represent actual fluctuations in intensity.)  Of course, this is just one shot, and we will need several more to make quantitative statements about the plasmoid securely.  Shot 9-09-10-05 shows the heated pinch column starting to expand away from the axis—the structure has been pretty much lost by this time.