#3 FAQ - Operating a Fusor - startup - run - shutdown
Posted: Wed Dec 09, 2009 2:28 pm
The vacuum part of a fusor is its life blood just as deuterium is its food.
This FAQ will begin assuming you have a fully assembled fusor system with.....
1. A standard two stage mechanical pump with good oil in it capable of a 10 micron vacuum at the inlet head.
2. A thermocouple gauge in the foreline between the mechanical pump and high vacuum pump
3. A good vacuum valve at the end of the foreline located near the outlet or low vacuum side of the high vacuum pump.
4. A diffusion, (diff), or turbo high vacuum pump, fully isolated with valving on each side of it (noted in points 3 and 5 here)
5. A gate or control bellows valve between the high vacuum pump's inlet, (diff pump), and the fusor. (We will call this the fusor valve)
6. A high vacuum gauge on the fusion chamber, itself.
7. A source of deuterium gas with a line leak valve, (needle valve), connected to the fusor. (We will call this the gas control valve)
8. A high voltage power supply that is fully and correctly metered
9. A protected viewing port or video camera/monitor combination to observe the inner grid area.
Question: With all of the above, how do I start and run a fusor to make fusion?
Take the following steps to obtain the proper vacuum and operational regime.
1. Make sure all high voltage power is off.
2. Make sure all vacuum valves are closed and that all vacuum gear and pump related power is off.
3. Turn on the camera/monitor system, if you have one. Turn on all radiation monitoring gear.
4. Turn on all vacuum gauges and metering.
5. Turn on the mechanical pump only.
6. Open the pump's gas ballast. The pump will be more noisey when this is done. Leave this ballast open until told to shut it again.
7. Let the pump run for a few minutes until the foreline is pumped down to well under 50 microns by reading the thermocouple, (TC), gauge. If it will not fall below 50 microns, you have a bad leak in the foreline or a bad mechanical pump. (It is best to allow this line to drop as low as practical.
8. Open the foreline to high vacuum pump valve. We will call this the "foreline valve". Open it all the way and leave it there until told to close it. The pump will load up and the pressure on the TC gauge will rise. This is normal. It will begin to fall again as the diff pump or turbo pump volume is pumped down. Hold at this point until the pressure on the TC gauge is again at its lowest point, but it has to be well under 50 microns. If not, you have a bad valve or seal at the inlet or outlet of the High vacuum pump. Once well below 50 microns, or as low as you can get the volume, proceed to the next step.
9. Open the gate or control valve (fusor valve) to the fusor. We will call this the "fusor valve". Again, the pressure will rise and the pump will load down as the entire fusor volume is pumped down.
10. Now look at both the foreline TC and high vacuum gauge on the fusor's readings. They should track somewhat alike. Again, you must acquire a vacuum with just the mechanical pump, on both gauges, indicating a pressure well below 50 microns before going to the next step. If not, you have a serious leak at the fusor chamber somewhere among its many ports and seals.
11. Close the gas ballast on the mechanical pump. The pressure might drop another 2-5 microns and the pump will get much quieter.
12. You now may start the high vacuum pump, turning on the turbo motor or, if you have a diff pump, turning on its boiler heater and cooling fan or cooling water flow.
13. If you have a turbo pump, the high vacuum gauge on the fusor will plummet rather quickly to some base pressure in the 10e-5 to 10e-7 torr range. If you have a diff pump, you will have to wait a few minutes for the boiler temperature to come up to operational temperatures. Ultimately, the high vacuum gauge will drop in pressure to well below 10e-5 torr or lower using the diff pump. You are now fully operational, vacuum wise.
Setting the deuterium gas flow for fusion********************************************
This is tricky and if you aren't careful you will waste your deterium and use it up at a prodigious rate. Follow these instructions carefully and monitor your high vacuum gauge constantly.
1. Close your, (fusor valve), gate or high vacuum pump control valve to the fusor. Unless you have a plus ultra system, the pressure will rise. As it rises, notice its rate of rise. It must be under 0.1 micron per second or 1X10e-4 torr per second. ( 1 micron every 10 seconds) If more than this, you are awfully leaky and will waste a bit of D2 gas.
2. Now that you have a feel for you leak rate, barely crack the (fusor) gate or bellows control valve to cause the pressure to start to drop again. Allow it to reach a stasis point where the pump is just keeping up with your leak rate.
3. Now barely cock open the gas control valve. This is a super fine adjustment. Let the gas in at a rate where you hit about 10 microns on the high vacuum gauge. ***note*** look at the TC gauge. It should still be in its low range of 10-50 microns. If it climbs and continues to do so, you have too much opening on the fusor valve. Turn off the gas control valve and close the fusor valve a tiny bit more. Repeat the gas admission process until you get a stable flowing gas pressure of at least 10 microns in the fusor that is stable against the high vacuum pump's pinched off fusor valve. This is an art that must be mastered.
4. Turn on the high voltage power supply and adjust it upward until a glow just lights. If the current draw is over 10ma, turn the power back or off. You must back off the gas pressure by ever so slightly reducing gas flow rate or opening the high vacuum valve to drop back to maybe 6 microns. This is a constant battle at startup but will stabilize. Try again to bring the voltage up until you get a glow.
5. Assuming you have a glow, that is stable at some voltage, V, and at a current under 10ma without the grid heating red hot, you have arrived at a point where real opeartion and fusion can begin. If the voltage is below 15kv you will need to nurse the system to higher voltages to do much fusion. To do this, try reducing the operating pressure. At 15kv, you will be be making x-rays and they will be pouring out of the viewing port. If you are well above 15kv, you should be detecting neutrons via whatever instrumentation you have and, thus, doing fusion. From this point on, it is a matter of controlling the fusor valve, the gas control valve and the power supply in such a manner that you can achieve a higher applied voltage at the highest gas pressure within the limits of overheating and damaging the grid. You are on your own.
Warning*** always glance at the TC gauge from time to time when running a fusor. It MUST remain, forever, below 50 microns and preferably below 40 microns. What is happening is that the flowing D2 gas is loading up the Diff pump and thus causing a rise in the foreline pressure. Normal, yes, but it needs to be monitored. More than about 50 microns on the TC gauge and you are just throwing away valuable D2 gas.
Shutting down after a run**********************************************
This is far more important to you than the startup procedure!! Mess up here and you will regret it later. You can now destroy your turbo pump or create a horrible mess in your fusor and all vacuum lines by burned diff pump oil with just one slip in the shutdown process.
1. Shut off all high voltage to the fusor.
2. Shut the deuterium gas control valve tight and shut off the D2 gas bottle valve as well.
3. Open the fusor valve, all the way. The pressure on the high vacuum gauge will now plunge as the high vacuum pump is no longer choked off or throttled back.
4. After a couple of minutes, close the fusor valve tightly. The fusor is now isolated from the vacuum system. and the pressure will start to rise on the high vacuum gauge. This is normal. Ignore it. If you wish, you can now shut off the high vacuum gauge electronics.
5. You may now shut off the turbo pump. Once it has wound down and stopped, go to the next step. If you have a diffusion pump, turn off the power to the heater on the boiler, but leave the cooling fan on or water flowing. Leave this cooling cycle running for at least 10-15 minutes. I let my boiler temperature fall below 50 deg C before turning off the fan or stopping the cooling water. proceed to the next step after turning off the cooling at the approriate time.
6. Close the foreline valve tightly
7. The TC gauge should now read well below 30 microns or your low, base, foreline pressure seen earlier in step #7.
8. You may now turn off the mechanical pump. It is important to let the mechanical pump's foreline up to air and not leave a vacuum in this small volume or it might lift oil up out of the pump, fouling the foreline. Do this now! It is assumed you can open the foreline to air by some artifice already in place, (valve, quick release coupling, whatever).
This completes the startup-run-shutdown cycle for a basic fusor outfitted as noted above.
Richard Hull
This FAQ will begin assuming you have a fully assembled fusor system with.....
1. A standard two stage mechanical pump with good oil in it capable of a 10 micron vacuum at the inlet head.
2. A thermocouple gauge in the foreline between the mechanical pump and high vacuum pump
3. A good vacuum valve at the end of the foreline located near the outlet or low vacuum side of the high vacuum pump.
4. A diffusion, (diff), or turbo high vacuum pump, fully isolated with valving on each side of it (noted in points 3 and 5 here)
5. A gate or control bellows valve between the high vacuum pump's inlet, (diff pump), and the fusor. (We will call this the fusor valve)
6. A high vacuum gauge on the fusion chamber, itself.
7. A source of deuterium gas with a line leak valve, (needle valve), connected to the fusor. (We will call this the gas control valve)
8. A high voltage power supply that is fully and correctly metered
9. A protected viewing port or video camera/monitor combination to observe the inner grid area.
Question: With all of the above, how do I start and run a fusor to make fusion?
Take the following steps to obtain the proper vacuum and operational regime.
1. Make sure all high voltage power is off.
2. Make sure all vacuum valves are closed and that all vacuum gear and pump related power is off.
3. Turn on the camera/monitor system, if you have one. Turn on all radiation monitoring gear.
4. Turn on all vacuum gauges and metering.
5. Turn on the mechanical pump only.
6. Open the pump's gas ballast. The pump will be more noisey when this is done. Leave this ballast open until told to shut it again.
7. Let the pump run for a few minutes until the foreline is pumped down to well under 50 microns by reading the thermocouple, (TC), gauge. If it will not fall below 50 microns, you have a bad leak in the foreline or a bad mechanical pump. (It is best to allow this line to drop as low as practical.
8. Open the foreline to high vacuum pump valve. We will call this the "foreline valve". Open it all the way and leave it there until told to close it. The pump will load up and the pressure on the TC gauge will rise. This is normal. It will begin to fall again as the diff pump or turbo pump volume is pumped down. Hold at this point until the pressure on the TC gauge is again at its lowest point, but it has to be well under 50 microns. If not, you have a bad valve or seal at the inlet or outlet of the High vacuum pump. Once well below 50 microns, or as low as you can get the volume, proceed to the next step.
9. Open the gate or control valve (fusor valve) to the fusor. We will call this the "fusor valve". Again, the pressure will rise and the pump will load down as the entire fusor volume is pumped down.
10. Now look at both the foreline TC and high vacuum gauge on the fusor's readings. They should track somewhat alike. Again, you must acquire a vacuum with just the mechanical pump, on both gauges, indicating a pressure well below 50 microns before going to the next step. If not, you have a serious leak at the fusor chamber somewhere among its many ports and seals.
11. Close the gas ballast on the mechanical pump. The pressure might drop another 2-5 microns and the pump will get much quieter.
12. You now may start the high vacuum pump, turning on the turbo motor or, if you have a diff pump, turning on its boiler heater and cooling fan or cooling water flow.
13. If you have a turbo pump, the high vacuum gauge on the fusor will plummet rather quickly to some base pressure in the 10e-5 to 10e-7 torr range. If you have a diff pump, you will have to wait a few minutes for the boiler temperature to come up to operational temperatures. Ultimately, the high vacuum gauge will drop in pressure to well below 10e-5 torr or lower using the diff pump. You are now fully operational, vacuum wise.
Setting the deuterium gas flow for fusion********************************************
This is tricky and if you aren't careful you will waste your deterium and use it up at a prodigious rate. Follow these instructions carefully and monitor your high vacuum gauge constantly.
1. Close your, (fusor valve), gate or high vacuum pump control valve to the fusor. Unless you have a plus ultra system, the pressure will rise. As it rises, notice its rate of rise. It must be under 0.1 micron per second or 1X10e-4 torr per second. ( 1 micron every 10 seconds) If more than this, you are awfully leaky and will waste a bit of D2 gas.
2. Now that you have a feel for you leak rate, barely crack the (fusor) gate or bellows control valve to cause the pressure to start to drop again. Allow it to reach a stasis point where the pump is just keeping up with your leak rate.
3. Now barely cock open the gas control valve. This is a super fine adjustment. Let the gas in at a rate where you hit about 10 microns on the high vacuum gauge. ***note*** look at the TC gauge. It should still be in its low range of 10-50 microns. If it climbs and continues to do so, you have too much opening on the fusor valve. Turn off the gas control valve and close the fusor valve a tiny bit more. Repeat the gas admission process until you get a stable flowing gas pressure of at least 10 microns in the fusor that is stable against the high vacuum pump's pinched off fusor valve. This is an art that must be mastered.
4. Turn on the high voltage power supply and adjust it upward until a glow just lights. If the current draw is over 10ma, turn the power back or off. You must back off the gas pressure by ever so slightly reducing gas flow rate or opening the high vacuum valve to drop back to maybe 6 microns. This is a constant battle at startup but will stabilize. Try again to bring the voltage up until you get a glow.
5. Assuming you have a glow, that is stable at some voltage, V, and at a current under 10ma without the grid heating red hot, you have arrived at a point where real opeartion and fusion can begin. If the voltage is below 15kv you will need to nurse the system to higher voltages to do much fusion. To do this, try reducing the operating pressure. At 15kv, you will be be making x-rays and they will be pouring out of the viewing port. If you are well above 15kv, you should be detecting neutrons via whatever instrumentation you have and, thus, doing fusion. From this point on, it is a matter of controlling the fusor valve, the gas control valve and the power supply in such a manner that you can achieve a higher applied voltage at the highest gas pressure within the limits of overheating and damaging the grid. You are on your own.
Warning*** always glance at the TC gauge from time to time when running a fusor. It MUST remain, forever, below 50 microns and preferably below 40 microns. What is happening is that the flowing D2 gas is loading up the Diff pump and thus causing a rise in the foreline pressure. Normal, yes, but it needs to be monitored. More than about 50 microns on the TC gauge and you are just throwing away valuable D2 gas.
Shutting down after a run**********************************************
This is far more important to you than the startup procedure!! Mess up here and you will regret it later. You can now destroy your turbo pump or create a horrible mess in your fusor and all vacuum lines by burned diff pump oil with just one slip in the shutdown process.
1. Shut off all high voltage to the fusor.
2. Shut the deuterium gas control valve tight and shut off the D2 gas bottle valve as well.
3. Open the fusor valve, all the way. The pressure on the high vacuum gauge will now plunge as the high vacuum pump is no longer choked off or throttled back.
4. After a couple of minutes, close the fusor valve tightly. The fusor is now isolated from the vacuum system. and the pressure will start to rise on the high vacuum gauge. This is normal. Ignore it. If you wish, you can now shut off the high vacuum gauge electronics.
5. You may now shut off the turbo pump. Once it has wound down and stopped, go to the next step. If you have a diffusion pump, turn off the power to the heater on the boiler, but leave the cooling fan on or water flowing. Leave this cooling cycle running for at least 10-15 minutes. I let my boiler temperature fall below 50 deg C before turning off the fan or stopping the cooling water. proceed to the next step after turning off the cooling at the approriate time.
6. Close the foreline valve tightly
7. The TC gauge should now read well below 30 microns or your low, base, foreline pressure seen earlier in step #7.
8. You may now turn off the mechanical pump. It is important to let the mechanical pump's foreline up to air and not leave a vacuum in this small volume or it might lift oil up out of the pump, fouling the foreline. Do this now! It is assumed you can open the foreline to air by some artifice already in place, (valve, quick release coupling, whatever).
This completes the startup-run-shutdown cycle for a basic fusor outfitted as noted above.
Richard Hull