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Homebrew Equipment A place to show, design and discuss the weird and wonderful electronic creations from the hands of individual members. |
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3rd May 2019, 12:02 pm | #21 |
Hexode
Join Date: Jul 2016
Location: Ashby de la Zouch, Leicestershire, UK.
Posts: 253
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Re: SparkChambers
Building now...…..
200mm dia x 200mm long acrylic cylinder with acrylic end plates. Power supply slung under base acrylic, from 15kV NST I stripped from my old SGTC. 10 ali plates spaced 20mm apart on nylon spacers and bolts with HV on alternate plates. Argon filled with telltale neoprene disc to show pressure increase as sparking will heat up gas. HV to be cut manually to start with. Maybe auto later. Model railway valves for Argon inlet/air outlet. Non pulsed HV to start with, as the first spark chambers had this so this is old fashion stuff. PS. I haven't forgotten 'Bach with sparks,' but as I said somewhere for the moment it's on 'the bach burner.'
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"One small step for man".....because he has arthritis. www.retinascope.co.uk Albert. |
5th May 2019, 10:11 am | #22 |
Hexode
Join Date: Jul 2016
Location: Ashby de la Zouch, Leicestershire, UK.
Posts: 253
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Re: SparkChambers
When a partical passing through my chamber ionises the Argon, ( I hope ),
the spark created will continue so I need to cut the HV after some short time. As I am finding, switching 20kV plus HV is rather costly so I will make a short period timer to cut the mains supply to the NST, if I can detect when a spark has been triggered by a partical and not spurious. This is all a new ball game for me and the next part of the game is ordering a small cylinder of Argon and a regulator. to suit. I think these will fit the bill from Machine Mart who is near to me...…….. https://www.machinemart.co.uk/p/argon-gas-cylinder https://www.machinemart.co.uk/p/bott...RoC6RQQAvD_BwE Maybe I ought to train up as a gas engineer.
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"One small step for man".....because he has arthritis. www.retinascope.co.uk Albert. Last edited by Viewmaster; 5th May 2019 at 10:19 am. |
5th May 2019, 3:49 pm | #23 | |
Guest
Posts: n/a
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Re: SparkChambers
Quote:
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25th May 2019, 7:25 pm | #24 | |
Octode
Join Date: Jan 2012
Location: Wimbledon, London, UK.
Posts: 1,464
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Re: SparkChambers
Quote:
Isn't it true to imagine that if helium can diffuse through the glass envelope of a valve, then it can also leak out of the valve too? This will depend on the partial pressure of helium on either side of the glass, not the total pressure difference, surely? Colin. |
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25th May 2019, 10:48 pm | #25 |
Moderator
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,801
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Re: SparkChambers
There's a well publicised issue of new iPhones using MMS resonators in vacuum packages instead of Quartz crystals. They are temporarily disabled by helium diffusion into the tiny vacuum chambers if there is raised helium density in the environment. Worth looking up as an illustration of helium diffusion.
David
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26th May 2019, 5:30 am | #26 | ||
Dekatron
Join Date: Jun 2015
Location: Biggin Hill, London, UK.
Posts: 5,190
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Re: SparkChambers
Quote:
As for helium diffusing out, this was certainly a problem with HeNe laser tubes when I was at school. They would lose the helium and stop working. |
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26th May 2019, 12:06 pm | #27 |
Dekatron
Join Date: Aug 2016
Location: Colchester, Essex, UK.
Posts: 4,081
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Re: SparkChambers
The pictures remind me of my Jacob's Ladder, c/w HT lead and Gabriel (starter) electrode. ('Arc-Angel' pun courtesy of BigClive!) The two HV resistors in series are around 5Meg each. The run time isn't long enough to overheat the Tupperware, as the bolts act as a good heatsink.
Dave |
26th May 2019, 6:56 pm | #28 | |
Octode
Join Date: Jan 2012
Location: Wimbledon, London, UK.
Posts: 1,464
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Re: SparkChambers
Quote:
What you need is a decent rotary pump and oil-diffusion pump or a turbo-molecular pump, plus the pipework, isolation valves, Pirani gauges and ionisation gauges. You never know, you might find just what you want in a skip. The last place that I worked at scrapped a Jeol GC-MS system and a VG ZAB! I worked on one of the early ZABs at the Royal Society Research Unit at Swansea University ages ago - beautiful reverse-geometry beasties. Oh, dear. I think I have just gone too far off-topic...sorry. Colin. |
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26th May 2019, 7:11 pm | #29 |
Nonode
Join Date: Jan 2016
Location: Stafford, Staffs. UK.
Posts: 2,529
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Re: SparkChambers
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26th May 2019, 7:51 pm | #30 |
Dekatron
Join Date: Sep 2007
Location: Oxfordshire, UK.
Posts: 4,310
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Re: SparkChambers
The HeNe laser is a very marginal device, to be honest. The single-pass gain can be as low as a percent or two. So the outcoupling has to be a good deal less than this, requiring a cavity Q of several hundred. Any slight misalignment of the mirrors, or optical absorption/scattering losses due to sputtered contamination, will snuff it out.
Cheers, GJ
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27th May 2019, 7:12 pm | #31 |
Heptode
Join Date: Jul 2010
Location: Wellington, New Zealand.
Posts: 653
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Re: SparkChambers
Just as a side issue I seem to recall bubble chambers for seeing radiation trails in 6th form physics using solid dry ice - is this the same or some different mechanism??
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27th May 2019, 7:49 pm | #32 |
Dekatron
Join Date: Sep 2007
Location: Oxfordshire, UK.
Posts: 4,310
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Re: SparkChambers
The solid dry ice ones would have been cloud chambers rather than bubble chambers, the latter being a superheated liquid and the former a supersaturated vapour. The passage of a high-energy subatomic particle leaves an ionisation trail behind it which then nucleates either condensation of the vapour (cloud chamber) or appearance of a trail of fine bubbles (bubble chamber). In a spark chamber the ionisation causes a gas discharge to develop. In some ways they're all similar, in others they're very different.
There were once some quite large liquid hydrogen bubble chambers at the lab where I spent most of my working life. By the time I arrived they had gone. But the huge (essentially immovable) concrete blast wall put in to direct the explosion fragments away from the staff in the event of an accident was still there ! Cheers, GJ
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