Potassium atoms are strongly sensitive to a magnetic field. This could relate to what is happening in the experiment where microwave radiation is applied to KCl (at least in the sense of ultra strong coupling to the gigahertz waves from the oven.)
The most sensitive magnetometer available , named SERF - comes from Princeton and consists of a cell containing potassium vapor and a buffer gas. The unpaired electrons on the potassium atoms are spin-polarized so that a probe detects the precession of spin in the presence of a magnetic field. This device is capable of incredible sensitivities on the order of 10-18 Tesla, 1000 times more sensitive than a SQUID detector. Thus microwave radiation, already efficient, can be utilized in a more efficient way - perhaps becoming strongly ionizing and splitting water. IOW it is possible that the extreme spin sensitivity of potassium to RF is a little understood effect -- maybe one looking for an application. ----------------------------- I like the sound of "something strange going on." Heck, it might be worthwhile to try various mixtures of KCl and NaCl to see if there is an obvious particular ratio where the sparking is maximized. Mills uses a pinhole technique for finding UV where he actually drills a sub-mm hole into the reactor wall with line of sight to the plasma, and mounts and glues a photocell UV detector chip over the hole - but that is for a vacuum reactor. Robin may have experience with this...? Michael Foster wrote: Some of the sparking looks a little too far from the surface of the glass container to be contaminated by it and there's a lot of sodium spectrum being displayed. So something strange is going on, I think.