WOW. Nice work.
No I have to clean my keyboard from drool....
Ready for assembly!
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richnormand
- Posts: 307
- Joined: Sat Aug 27, 2005 8:30 am
- Real name: rich normand
Re: Ready for assembly!
Hey, Nice start of the chamber. I'm going to do a chamber similar to yours. Why do you use the ratable conflats? Whats the difference from them to the non-rotatable?
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Richard Hester
- Posts: 1519
- Joined: Thu Jul 05, 2001 12:07 am
- Real name:
Re: Ready for assembly!
For diff pump oil, I would use silicone oils like DC704 and DC705 (or their equivalents). They much more affordable than Santovac and allow very respectable ultimate pressure without a cooled baffle. They also withstand oxidation much better than the cheap Octoil and equivalents, so an occasional up-to-air accident won't turn your oil charge into caramel. The mass spectrometer folks hate the silicone oils because of the extra ionic species they introduce (they use Santovac), but this should not be an issue with the fusor.
If you're using a huge 10" (or larger) pump, Octoil starts to look attractive because of the sheer cost of the oil charge, but for a little pump requiring only 50cc or so of oil, silicone is a good bet.
If you're using a huge 10" (or larger) pump, Octoil starts to look attractive because of the sheer cost of the oil charge, but for a little pump requiring only 50cc or so of oil, silicone is a good bet.
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lutzhoffman
- Posts: 188
- Joined: Mon Dec 07, 2009 8:59 pm
- Real name:
Re: Ready for assembly!
Hello:
Ref Fluids:
DC 705, and DC 704 are nice, but they have one problem, which may not be a problem with fusor application, but this IS a problem with electron microscopes, potential drop accelerators etc. The problem is that if you get any backsteaming, under discharge, ion / electron beam conditions. These silicon fluids can form insulating layers of SiO2 (Quartz) on the inside surfaces in the vacuum tank, or tube etc. This can affect the potential distribution, and HV properties, and even ruin a tube. Non silicon fluids tend to deposit carbon if anything, which is easy to deal with in comparison. Silicon fluids also have some solubility issues with many common solvents that are often used for cleaning, so you have to select the right solvent, if you need to clean your DP, or something else in your system. Maybe someone else has fusor specific knowlege as to if SiO2 deposits can be problematic in a fusor? I just do not know the answer to this question.
I ran DC 704 for years, for a coating chamber, and it worked very well, but now I use Santovac after getting 500ml on ebay for cheap, I would never go back to DC- 704 silicon fluid: No more cold traps between the DP and chamber, just a butterfly valve, and a cold cap which is built into my HS 2 DP. Plus if I were to loose vacuum again, due to breakage etc, its no big deal with Santovac, it tends to decompose into H2O and CO2 gas if somehow you get it that hot, which is not likely. I have lost vacuum at full temp more than once, due to breakage of glass parts etc, each time I first freaked out, and sweated it, until I checked the DP fluid, and all was fine.
My friend uses Diffoil 20 only, in both his roughing pump, and in his DP. His system works very well, and he has not had any major problems. He has a homemade 2 stage thermo-electric cooled trap between his DP, and his chamber. Very creative setup, he claims to get down to about -5C in the inside of the trap. The 2 stage thermo-electric cooler / fan is on the outside, and a foam insulated thick copper HV vac. feedthrough sucks the heat from the vacuum side copper baffle plate, to the external TC cooling setup,
He still has a cheap copper wool trap still between the DP, and the RP. His reason is: Even though he uses the same fluid in the DP, and in the RP, the lighter fraction breakdown products from the DP, and contaminants etc. will build up in the RP oil, he does not want these to migrate back into the DP. I have no idea if this is valid, but he is a "smart cookie", being a retired Xerox corp. engineer, with much partical experience, so I just accept his reasoning. His original cold trap was a dry ice acetone alchohol setup, which was much colder, but he is getting away with the -5C system now.
Octoil is toxic, and a suspected mutagen, with few advantages, which is why hardly no one uses it anymore, unless they have, or find a bottle for cheap somewhere. So in the end you have to decied what is best for you, and maybe for your health. Octoil cannot be that bad I suppose, because the subacate ester is used to keep C-4 plastic explosive pliable, and after my military years in the late 80's, my kids all look normal, well almost, but that's not genetic : )
No one else can tell you what is best for you, only knowlege gained can help you do this, and to select the correct fluid. Doug who contibutes to this column a lot, runs diffoil20 in his DP, and RP. He is of course not always correct, but he has actually converted my thinking on several issues, so I see him as one of the "bright bulbs" along with Carl, Richard, John and so many others in this column. These folks are people who actually build, and use the stuff that they are posting about in real life, which in my mind counts for something : )
Personally I like the fill and forget features of Santovac, and the elimination of the trap between my DP, and my chamber. I mention this only because when you look at prices, its more complicated than just the oil cost, because for example how much does a trap cost to buy, and then to fill? Yes you can probably eliminate the trap with DC 705 also, at a lower cost, but are you willing to accept the other aspects of silicon fluid? I cannot because I like DC potential drop accelerators, otherwise my pump could have DC-705 in it, jut the same. I am sure that with a little bit of reading, of past threads on this subject, you will figure it out. You have my respect already since you are a builder, so I will look forward to the day where you help me solve some problem, take care....
PS: Put a big fan on that DP with some sheet metal, plastic etc. to direct the air, a PC fan is to anemic, but a big 6" + fan from some other big IT item will work.
Ref Fluids:
DC 705, and DC 704 are nice, but they have one problem, which may not be a problem with fusor application, but this IS a problem with electron microscopes, potential drop accelerators etc. The problem is that if you get any backsteaming, under discharge, ion / electron beam conditions. These silicon fluids can form insulating layers of SiO2 (Quartz) on the inside surfaces in the vacuum tank, or tube etc. This can affect the potential distribution, and HV properties, and even ruin a tube. Non silicon fluids tend to deposit carbon if anything, which is easy to deal with in comparison. Silicon fluids also have some solubility issues with many common solvents that are often used for cleaning, so you have to select the right solvent, if you need to clean your DP, or something else in your system. Maybe someone else has fusor specific knowlege as to if SiO2 deposits can be problematic in a fusor? I just do not know the answer to this question.
I ran DC 704 for years, for a coating chamber, and it worked very well, but now I use Santovac after getting 500ml on ebay for cheap, I would never go back to DC- 704 silicon fluid: No more cold traps between the DP and chamber, just a butterfly valve, and a cold cap which is built into my HS 2 DP. Plus if I were to loose vacuum again, due to breakage etc, its no big deal with Santovac, it tends to decompose into H2O and CO2 gas if somehow you get it that hot, which is not likely. I have lost vacuum at full temp more than once, due to breakage of glass parts etc, each time I first freaked out, and sweated it, until I checked the DP fluid, and all was fine.
My friend uses Diffoil 20 only, in both his roughing pump, and in his DP. His system works very well, and he has not had any major problems. He has a homemade 2 stage thermo-electric cooled trap between his DP, and his chamber. Very creative setup, he claims to get down to about -5C in the inside of the trap. The 2 stage thermo-electric cooler / fan is on the outside, and a foam insulated thick copper HV vac. feedthrough sucks the heat from the vacuum side copper baffle plate, to the external TC cooling setup,
He still has a cheap copper wool trap still between the DP, and the RP. His reason is: Even though he uses the same fluid in the DP, and in the RP, the lighter fraction breakdown products from the DP, and contaminants etc. will build up in the RP oil, he does not want these to migrate back into the DP. I have no idea if this is valid, but he is a "smart cookie", being a retired Xerox corp. engineer, with much partical experience, so I just accept his reasoning. His original cold trap was a dry ice acetone alchohol setup, which was much colder, but he is getting away with the -5C system now.
Octoil is toxic, and a suspected mutagen, with few advantages, which is why hardly no one uses it anymore, unless they have, or find a bottle for cheap somewhere. So in the end you have to decied what is best for you, and maybe for your health. Octoil cannot be that bad I suppose, because the subacate ester is used to keep C-4 plastic explosive pliable, and after my military years in the late 80's, my kids all look normal, well almost, but that's not genetic : )
No one else can tell you what is best for you, only knowlege gained can help you do this, and to select the correct fluid. Doug who contibutes to this column a lot, runs diffoil20 in his DP, and RP. He is of course not always correct, but he has actually converted my thinking on several issues, so I see him as one of the "bright bulbs" along with Carl, Richard, John and so many others in this column. These folks are people who actually build, and use the stuff that they are posting about in real life, which in my mind counts for something : )
Personally I like the fill and forget features of Santovac, and the elimination of the trap between my DP, and my chamber. I mention this only because when you look at prices, its more complicated than just the oil cost, because for example how much does a trap cost to buy, and then to fill? Yes you can probably eliminate the trap with DC 705 also, at a lower cost, but are you willing to accept the other aspects of silicon fluid? I cannot because I like DC potential drop accelerators, otherwise my pump could have DC-705 in it, jut the same. I am sure that with a little bit of reading, of past threads on this subject, you will figure it out. You have my respect already since you are a builder, so I will look forward to the day where you help me solve some problem, take care....
PS: Put a big fan on that DP with some sheet metal, plastic etc. to direct the air, a PC fan is to anemic, but a big 6" + fan from some other big IT item will work.
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Richard Hull
- Moderator
- Posts: 15024
- Joined: Fri Jun 15, 2001 9:44 am
- Real name: Richard Hull
Re: Ready for assembly!
I will be using pentavac/santovac in fusor V which will be underway after the HEAS conference should I decide to use my old diff pump instead of my 10" Turbo pump.
I picked up a thermo-electric cooler mounted on a 2" Veeco diff pump that is air cooled last weekend for $40.00 at a Teslathon. It came with a bottle of 704. I may use my old diff pump with the coller added of move over to the Veeco. We will see.
The turbo is water cooled and I don't like that. I have had the thing for years, but just am resisting the flowing water bit.
Richard Hull
I picked up a thermo-electric cooler mounted on a 2" Veeco diff pump that is air cooled last weekend for $40.00 at a Teslathon. It came with a bottle of 704. I may use my old diff pump with the coller added of move over to the Veeco. We will see.
The turbo is water cooled and I don't like that. I have had the thing for years, but just am resisting the flowing water bit.
Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment