Magnetron ion source for Carl's Jr.
Posted: Mon Dec 04, 2006 4:01 pm
Here is a cross-section diagram of the ion source currently in use on the Carl's Jr. fusor (see viewtopic.php?f=6&t=2648#p12158)
The total cost of the brand-new parts needed to make one of these is probably under $100. The magnets are made by stacking grade N42 cube NdFeB magnets into stacks, then aligning and fixing the stacks into a row with N poles all in one direction and S poles all in the other. The diagram depicts how the magnetic poles should be aligned. Note that these magnets will want to fly apart with great force and care must be taken to hold them together. I use aluminum duct tape with good results.
The major strengths of this design are the simplicity (minor machining and brazing is called for) and the versatility (any of the 5/8" feedthroughs sold by CeramTec can be used with the quick connect, and the position of the end of the stalk can be varied by moving it up and down in the quick connect). The major weakness is that we have viton o-rings and NdFeB magnets, neither of which tolerate the high temperatures that this ion source may generate unless precautions are taken. Another weakness is that this source will not work AT ALL iif it is reverse-polarized (e.g. center electrode negative).
Improving this ion source is the subject of my active work now and I will post updates specifically about this source here.
-Carl
The total cost of the brand-new parts needed to make one of these is probably under $100. The magnets are made by stacking grade N42 cube NdFeB magnets into stacks, then aligning and fixing the stacks into a row with N poles all in one direction and S poles all in the other. The diagram depicts how the magnetic poles should be aligned. Note that these magnets will want to fly apart with great force and care must be taken to hold them together. I use aluminum duct tape with good results.
The major strengths of this design are the simplicity (minor machining and brazing is called for) and the versatility (any of the 5/8" feedthroughs sold by CeramTec can be used with the quick connect, and the position of the end of the stalk can be varied by moving it up and down in the quick connect). The major weakness is that we have viton o-rings and NdFeB magnets, neither of which tolerate the high temperatures that this ion source may generate unless precautions are taken. Another weakness is that this source will not work AT ALL iif it is reverse-polarized (e.g. center electrode negative).
Improving this ion source is the subject of my active work now and I will post updates specifically about this source here.
-Carl