Made a second fusion attempt today with a deuterium plasma. Using the new power supply and the mass flow controller together produced very stable plasmas. I tried a variety of voltages, currents, and pressures but no bubbles.
I have two hypotheses:
a) we are producing fusion, but the detector is not showing it.
b) we are not producing fusion because of grid misalignment.
While double checking the bubble detector, I noticed a relevant detail: the bubble detector must operate within 20˚ C to 40˚C. Today the room temperature was 16˚C. The detector has a built in liquid crystal thermometer. Black means the detector is out of range. To correct this, I put the detector in my pocket for 20 minutes. This warmed the detector to 34˚C :
I want to get a geiger counter as a double check for the bubble detector. The geiger counter would respond to x-rays produced during fusion.
But really I think the problem is that our inner and outer grids are completely misaligned. From what I’ve read grid alignment is necessary for “star mode”. And it seems this is necessary for fusion.
It should be pretty easy to fabricate a new/better pair of grids.
Although we didn’t get fusion today, it was a success in other ways. The system is working smoothly. We have stable plasmas with voltages as high as -17kV. The mass flow controller minimized the deuterium use.
The mass flow controller also lets me adjust the gas flow at a safe distance, which is a welcome upgrade.
Here is a video of the deuterium plasma:
Prometheus Fusion Perfection 
Did you release the pressure in the bubble detector before use?
You may not be driving hard enough.
Richards fusor may be a good example of Volts vs neutrons and you may be able to guestimate the number of neutrons you may be producing.
http://www.fusor.net/board/view.php?bn=fusor_construction&key=1255960113
Hope this helps.
I did release the pressure on the bubble detector per the instructions.
Sorry to ask the obvious, Iv’e never bought one so was unaware it came with instructions. Star mode is most prevalent at low pressures from 30 to 10 microns and I think it has to do with the mean free path ie once the MFP exceeds the dimensions of your fusor the ions essentially travel in straight lines forming the star pattern where grid collisions knock out the ions in the gaps in the star pattern leaving beams of relatively stable orbits.
That sounds correct.
Also:
“In the fusor, good geometrical alignment of the inner grid structure is important.”
from
http://www.energeticforum.com/renewable-energy/4849-philo-t-farnsworth-ed-gray-tubes.html