Search found 1222 matches

by John Futter
Wed Jan 23, 2008 10:00 pm
Forum: Fusor Construction & Operation (& FAQs)
Topic: One-inch diameter 316 SS solid cathode test
Replies: 44
Views: 11291

Re: One-inch diameter 316 SS solid cathode test

<t>Jon<br/> Well done<br/> I have calculated the depth of implant for your cathode it may help with answering yield at higher voltages. to get implant depthmaximum take projected range minus longitudinal straggling to get the max atoms implanted per sq cm<br/> <br/> Edit: this post has an inline att...
by John Futter
Tue Dec 18, 2007 5:56 am
Forum: Vacuum Technology (& FAQs)
Topic: Aluminium Foil
Replies: 3
Views: 2564

Re: Aluminium Foil

<t>Also<br/> Aluminium is soft and it protects the knife edges on the CF's if you inadvertantly put them down too heavily, clunk the next fitting on top while doing a trial fitting ETC.<br/> Cooking foil is fine but use several layers to help with above, the vacuum stuff is alot thicker.<br/> foil i...
by John Futter
Fri Dec 14, 2007 1:40 am
Forum: Vacuum Technology (& FAQs)
Topic: Diffusion pump control methods
Replies: 3
Views: 2389

Re: Diffusion pump control methods

<t>In my opinion it is better to run the diff pump at its rated current / voltage and control pumping speed with a throttle valve (ie gate valve, butterfly valve or similar). Slowing the pumping speed by changing the temperature inside tends to change its pumping speed faster for lighter gases ie hy...
by John Futter
Thu Dec 06, 2007 9:14 am
Forum: Vacuum Technology (& FAQs)
Topic: Pump vibration & flexible piping
Replies: 8
Views: 3052

Re: Pump vibration & flexible piping

<t>Remember pumping speed depends on length to diameter ratio of your system (differential pumping)<br/> As an example ; at work we have an experimental chamber that is pumped by an ion pump, titanium sublimation pump and a Phieffer turbo, the chamber sits at 2 by ten to the minus 9 millibar and is ...
by John Futter
Thu Dec 06, 2007 7:16 am
Forum: Fusor Construction & Operation (& FAQs)
Topic: Chamber Complete
Replies: 6
Views: 3122

Re: Chamber Complete

<t>Glen <br/> very good first attempt<br/> bit too much current but should be relatively leak free -time will tell.<br/> I see the acetone there if you suspect a leak when roughing down a sqeeze bottle to put some round the welds slowly may help find the leaky one. As it is drawn in the vapour press...
by John Futter
Wed Dec 05, 2007 8:09 pm
Forum: Fusor Construction & Operation (& FAQs)
Topic: Tig Welding: Filler Metal
Replies: 10
Views: 4238

Re: Tig Welding: Filler Metal

<t>To clean the SS after welding two things should be done. firstly while the fixture is still hot cover all areas near the weld with weld pickle available from your nearest welding supply depot. This pickle cleans and repassivates the surface so that the SS becomes stainless again. It will remove t...
by John Futter
Tue Dec 04, 2007 8:11 am
Forum: Fusor Construction & Operation (& FAQs)
Topic: Tig Welding: Filler Metal
Replies: 10
Views: 4238

Re: Tig Welding: Filler Metal

Sorry forgot to say 1/16 electrode or 3/32 electrode.
Smaller electrode concentrates heat to a smaller melt zone hence the small cup size to make sure argon is around job.
make sure prepurge is on and as long a post purge on torch that you can afford
by John Futter
Mon Dec 03, 2007 6:50 am
Forum: Fusor Construction & Operation (& FAQs)
Topic: Tig Welding: Filler Metal
Replies: 10
Views: 4238

Re: Tig Welding: Filler Metal

3/8 nozzle let electrode protrude 0.5 inch ground not at 30 degrees but more like 15 degrees ie long taper.
practice on scrap bits first ie same thickness to get technique right
by John Futter
Mon Dec 03, 2007 12:02 am
Forum: Fusor Construction & Operation (& FAQs)
Topic: Tig Welding: Filler Metal
Replies: 10
Views: 4238

Re: Tig Welding: Filler Metal

should be fine without filler. make sure that tunsten tip is needle sharp and play most of the heat on the conflat to melt that to the hemisphere. 6 - 8 small tack joins around the thing first. Yuo should only need around 40 -50 amps.
by John Futter
Sun Dec 02, 2007 8:28 pm
Forum: Ion Gun Design and Construction (& FAQs)
Topic: Ion Focus / ZnS Screen
Replies: 9
Views: 6563

Re: Ion Focus / ZnS Screen

<t>This technique works well to although similar to the already stated the colloidon binds it all together and it does work with ZnS. Lifted off an electron microscope user group the article in full<br/> ""To all interested:<br/> As I said I used green phosphor from JEOL, cat. # 423-011. Call and se...