Tungsten filaments are usually very beefy in real "He-Man" ion guns. They are usually 18 gauge wire minimum or multistranded finer gauge wires wrapped up to nearly 8 gauge equivalents!!! Lots o' amps to get lot o' ions.
I attach an image of some of the multicore heavy duty jobs I have in my element stock.
As ion guns work in the 10 micron and under pressures, the tungsten WILL slowly erode and deposit on everything within the gun. Thus all ion guns in this catagory are definitely in the high maintenance catagory.
Make sure you design a gun for disassembly, component replacement and easy cleaning. All of this is why we don't all have "sea mine" fusors looking like porcupines with ion guns all over them. At our level of operation, all ionizer filaments will be sacrificial in nature. Note!! Nice Iridium filaments will not oxidize or chemically react at some rather high pressures. Got heavy gauge Iridium??
All this talk of coated filaments is a bit premature. At our pressures, poisoning of the coatings and reduction or degradation of performance would be a regular occurance. These coatings work much better at 10e-5 torr or deeper vacuums.
We will have to "bull-head" our ions into existence with good old raw, sacrificial tungsten and a gang o' amps on the fils.
I have toyed with the idea of a high current, thoriated tungsten rod micro arc sourcing the electrons. It might be worth the effort.
Richard Hull
Tunsten ion gun filaments
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Richard Hull
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Tunsten ion gun filaments
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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
Re: Tunsten ion gun filaments
Hi Richard:
That is quite an assortment of filaments.
Phil has provided some really good filaments in heavy gauge tungsten. I usually run them at 10 amps.
The first picture is the filament on the original mount as a gun for a laser.
Happy Fusoring!
Larry Leins
Fusor Tech
That is quite an assortment of filaments.
Phil has provided some really good filaments in heavy gauge tungsten. I usually run them at 10 amps.
The first picture is the filament on the original mount as a gun for a laser.
Happy Fusoring!
Larry Leins
Fusor Tech
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- gun5.JPG (26.13 KiB) Viewed 4257 times
Re: Tunsten ion gun filaments
Hi folks:
A filament mount built by Phil:
Two insulators a gas inlet in copper and a 13/16 conflat port on the back ( Yes conflat does get that small)
A filament mount built by Phil:
Two insulators a gas inlet in copper and a 13/16 conflat port on the back ( Yes conflat does get that small)
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- gun4.JPG (25.78 KiB) Viewed 4257 times
Re: Tunsten ion gun filaments
If we all had our wish list out. What type of cathode would be best ( material and coating ) for our ion guns. I have to put another order into the cathode people and now is a good time to get pricing. Do we want the cathode to be an electron emitter? The cathodes I have here are very heavy duty. Even if the material is tungsten, irridium or other that can hold up better to D2 let me know.
Re: Tunsten ion gun filaments
You know, I think I just might know where you can get really high
quality, professionally made ion guns for next to nothing simply
because the timing is right. I am the RF Systems Engineer here at
KLRU-TV in Austin, Tx and all the other UHF TV engineers in our
market have sadly noted that our very expensive klystron tube
amplifiers have suddenly assumed scrap value with the FCC
mandated conversion from NTSC to ATSC digital tv. Now the only
game in town for high-powered UHF RF is the MSDCIOT (Multistage,
Depressed-Collector, Inductive Output Tube). Those of us who are
making the transition to high-powered digital TV are having to
temporarily operate two complete transmitter plants simultaneously
while the public warms to the idea of digital TV (and the prices drop).
This means enormous power bills (> 30 k$/mo for us) and we're all
having to scrap at least one functioning backup NTSC transmitter to
make room for the new guy in the building. Usually, the backup is an
older RCA or Harris klystron model with at least two klystrons in the
amps and one or two in crates as spares. When we scrapped our
1977 RCA model, I dutifully pulled both Varian klystrons, packed them
up with our two spares and called the usual rebuilders that only a year
earlier had bought one spare from us for $18,000. I was amazed to
find out that because of the digital conversion and resulting glut of
klystrons that nobody was willing to pay us more than the freight to get
them to the plant. With a heavy heart I cut four beautiful $30,000
klystrons up into scrap for the recycler. Only then did I get a chance to
see the beautifully engineered heater-cathode structure inside these
tubes. They are indirectly-heated capsules that completely surround
the tungsten ribbon, preventing tungsten deposition inside the tube.
They normally run at 6 volts and draw 22.5 amps for a beam current
as high as 5 or 6 amps (27-32 kvdc beam voltage). These would be
perfect for fusor use and I would be willing to bet that any UHF
broadcaster in your area might have one or two of these klystrons just
sitting around gathering dust. Give the station a call and see what you
can get one for. You might be surprised.
Frank
Franklin Roberts
RF Systems Engineer
KLRU-TV Austin, Texas
(512) 475-9069
quality, professionally made ion guns for next to nothing simply
because the timing is right. I am the RF Systems Engineer here at
KLRU-TV in Austin, Tx and all the other UHF TV engineers in our
market have sadly noted that our very expensive klystron tube
amplifiers have suddenly assumed scrap value with the FCC
mandated conversion from NTSC to ATSC digital tv. Now the only
game in town for high-powered UHF RF is the MSDCIOT (Multistage,
Depressed-Collector, Inductive Output Tube). Those of us who are
making the transition to high-powered digital TV are having to
temporarily operate two complete transmitter plants simultaneously
while the public warms to the idea of digital TV (and the prices drop).
This means enormous power bills (> 30 k$/mo for us) and we're all
having to scrap at least one functioning backup NTSC transmitter to
make room for the new guy in the building. Usually, the backup is an
older RCA or Harris klystron model with at least two klystrons in the
amps and one or two in crates as spares. When we scrapped our
1977 RCA model, I dutifully pulled both Varian klystrons, packed them
up with our two spares and called the usual rebuilders that only a year
earlier had bought one spare from us for $18,000. I was amazed to
find out that because of the digital conversion and resulting glut of
klystrons that nobody was willing to pay us more than the freight to get
them to the plant. With a heavy heart I cut four beautiful $30,000
klystrons up into scrap for the recycler. Only then did I get a chance to
see the beautifully engineered heater-cathode structure inside these
tubes. They are indirectly-heated capsules that completely surround
the tungsten ribbon, preventing tungsten deposition inside the tube.
They normally run at 6 volts and draw 22.5 amps for a beam current
as high as 5 or 6 amps (27-32 kvdc beam voltage). These would be
perfect for fusor use and I would be willing to bet that any UHF
broadcaster in your area might have one or two of these klystrons just
sitting around gathering dust. Give the station a call and see what you
can get one for. You might be surprised.
Frank
Franklin Roberts
RF Systems Engineer
KLRU-TV Austin, Texas
(512) 475-9069
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Alex Aitken
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Re: Tunsten ion gun filaments
If I'm reading the thread right its not the simple design thats the problem. The high pressure (of D2) the fusor requires causes the guns filement to sputter from ion impacts. Its probably this more than evaporation thats the problem. If this is the case a fancy electron source from an ultra high vacuum tube wont be much more help even if it can be fabricated as part of an ion source.