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3_12_18 first good rf neutrons

PostPosted: Mon Mar 12, 2018 6:08 pm
by Doug Coulter
Well, interesting day. Got the fusor up with the RF drive, way NOT optimized, but got some decent neutron counts. From the scopes and the data, in this mode it's a little lower Q average (see the grid heating, and this is on ~360w input to the driver, so less to the grid) but some really good peaks when it drifted into a good timing.
Sadly, this run also took out the 2nd $80 chinese power supply for no obvious reason. Doesn't seem to matter which vendor on amazon...it's the same innards, and this fried at 6 amp output - rated at 10. I'll try to get a post mortem on these and see if they are repairable.
I found running the stepup transformer off resonance (which is also lower effective stepup ratio) seems a bit more efficient - Less heat in things not supposed to get hot an any rate - and off resonance is most of the available frequency range. Really high frequencies seem to have the parallel resonance issue and I just could not get much voltage output (didn't draw much input current either). If that turns out to be where we want to be, I'll hope some external C or L will help there.

To the pictures:
b2.PNG
big scope

Green is the furthest faraday, which has a semi loaded ion grid "in the way" - the DC ion supply is wired up, but not on, shielding this one a little bit I'd guess.
Blue is the near faraday probe - the one that looks like a 2.4 ghz antenna (it is that too).
Violet is an ac coupled pickup a few inches from the end of the HV feedthrough (near the tank end).
Yellow is neutron (hornyak). When this is clipped, like here, it seems to mean a neutron burst.
ss2.PNG
Yellow is HV probe on grid. Blue is xfrmr input one side.
ss2.PNG (8.38 KiB) Viewed 3810 times

12marNeut.png
Some data in the db for this one.

I was running 60 to 65 khz in this (before the DC PS fried). It looked to me like about 1/3 of the grid volts were positive, and 2/3 negative, corresponding very roughly to +10 kv and -20 kv here.

The grid got pretty hot - hotter than it does with the normal DC conditions for the roughly same drive power (here I only know what I put *in* to the stepup xfrmr, or that minus the wires from the PS, which get warm...)
im_0003_20180312_181022.jpg
The grid at equilibrium