Re: All journeys
Posted: Sat Mar 26, 2011 2:41 pm
To your first question, yes, D will give a nice reddish color with air (nitrogen). You saw what it looks like when pure here. Sadly, it's hard to go by the camera pix I have up, as the camera messes up the color a little. A hydrogen glow at medium high pressures is kind of red, it gets more purple as the pressure goes down.
You've got more than one thing going on at a time here. Your system hasn't been "conditioned" yet, and so it will act fairly strange until that process is done with, just run the thing and it will get better. I've seen that weird stuff with voltage rise here too -- nothing too weird going on there, just knocking invisible bits of dust and dirt off things.
Once that is complete, you need a vacuum that can completely shut the glow off at full voltage. You should just set the supply for 30 or 40kv and a low current limit, say 5 ma or so, and try to get it where it's drawing nothing at full voltage -- if you can do that, you're there. It will only take a tiny amount of gas over the full-off vacuum level (which you should note on your gage when you find that spot where it just goes out all the way -- it's more accurate and repeatable than most gages!) to be in fusion territory. When you can get that -- try running about 10 ma, which for us is right on a "sweet spot". Remember 10 ma at 40kv is 400w -- so things are going to get hot quick -- pay attention to that so you don't melt things. If you can hold 20kv with D in there, you'll start having enough neutrons for your detector to count, not many, but some. It will go up hugely with voltage (it's still going up fast when I hit 53kv, my current maximum).
Here we put some black hi-temp paint on the tank (sold for hot rod headers) so we can use an IR thermometer to watch that. It's easy to get to a couple hundred C if you're not paying attention, and some things may not like that very much. IR thermometers don't read right on stainless steel -- it has a weird emissivity. They'll read quite low on it. You could also put a thermocouple here and there if that's more to your liking. I like the IR because being able to do it from a distance is kind of neat (and keeps me away from the HV) and you can scan it around and learn things easily.
Once you've had D in the tank, there will always be a little in there -- driven into the various tank metal components, which will come back out when they are heated. I see it on my mass spectrometer here anytime I get the thing hot, even if I haven't run for a long time. Doesn't take much!
Sounds like you're really really close now. I'd start going up in voltage, working your way up slow, which means adjusting the gas pressure till you can get to say 20kv (with it "lit off"), then 30, then 40. You'll see some spitting and sparking -- run at each voltage till that stops, then move up (by lowering the gas pressure). You do want to do that with D or hydrogen. At first, this takes awhile to get done, but after it's been done, it's good till you open the tank again, more or less. It takes my new grids about 30 minutes of conditioning before they get "good" -- but only if that's the only thing that changed, and I didn't have the tank open for more than the few seconds it takes to make the change. Leave it open for a day, and you start all over again, and that takes hours.
You can do this with the supply set for the full voltage, and some low current limit, and get all your levels conditioned by nothing but changing the gas pressure -- that's what I do and it's the quickest and easiest way I've found. You just watch the voltage on the supply while you adjust the gas stuff.
You've got more than one thing going on at a time here. Your system hasn't been "conditioned" yet, and so it will act fairly strange until that process is done with, just run the thing and it will get better. I've seen that weird stuff with voltage rise here too -- nothing too weird going on there, just knocking invisible bits of dust and dirt off things.
Once that is complete, you need a vacuum that can completely shut the glow off at full voltage. You should just set the supply for 30 or 40kv and a low current limit, say 5 ma or so, and try to get it where it's drawing nothing at full voltage -- if you can do that, you're there. It will only take a tiny amount of gas over the full-off vacuum level (which you should note on your gage when you find that spot where it just goes out all the way -- it's more accurate and repeatable than most gages!) to be in fusion territory. When you can get that -- try running about 10 ma, which for us is right on a "sweet spot". Remember 10 ma at 40kv is 400w -- so things are going to get hot quick -- pay attention to that so you don't melt things. If you can hold 20kv with D in there, you'll start having enough neutrons for your detector to count, not many, but some. It will go up hugely with voltage (it's still going up fast when I hit 53kv, my current maximum).
Here we put some black hi-temp paint on the tank (sold for hot rod headers) so we can use an IR thermometer to watch that. It's easy to get to a couple hundred C if you're not paying attention, and some things may not like that very much. IR thermometers don't read right on stainless steel -- it has a weird emissivity. They'll read quite low on it. You could also put a thermocouple here and there if that's more to your liking. I like the IR because being able to do it from a distance is kind of neat (and keeps me away from the HV) and you can scan it around and learn things easily.
Once you've had D in the tank, there will always be a little in there -- driven into the various tank metal components, which will come back out when they are heated. I see it on my mass spectrometer here anytime I get the thing hot, even if I haven't run for a long time. Doesn't take much!
Sounds like you're really really close now. I'd start going up in voltage, working your way up slow, which means adjusting the gas pressure till you can get to say 20kv (with it "lit off"), then 30, then 40. You'll see some spitting and sparking -- run at each voltage till that stops, then move up (by lowering the gas pressure). You do want to do that with D or hydrogen. At first, this takes awhile to get done, but after it's been done, it's good till you open the tank again, more or less. It takes my new grids about 30 minutes of conditioning before they get "good" -- but only if that's the only thing that changed, and I didn't have the tank open for more than the few seconds it takes to make the change. Leave it open for a day, and you start all over again, and that takes hours.
You can do this with the supply set for the full voltage, and some low current limit, and get all your levels conditioned by nothing but changing the gas pressure -- that's what I do and it's the quickest and easiest way I've found. You just watch the voltage on the supply while you adjust the gas stuff.