Plasmagun/railgun for Stelarate

For the design and construction details of ion guns, necessary for more advanced designs and lower vacuums.

Re: Plasmagun/railgun for Stelarate

Postby Andrew Haynes » Sun Feb 05, 2017 1:10 am

@Dennis P Brown
The idea is to have a 10 turn coil about 500*200mm, made of steel pipe 10mm Id with 16mm Od, at each turn a spark gap and magnetic .
I'm not sure of the induction but if I can get a couple thousand amps flowing throughout the plasma would be good.
The pulse should get to 20000K increase the meanfreepath and at the same time lower the resistance.

@Rex Allers and Richard Hall
Being working on the safety and capacity, the picture below is abit better, plan to solder the connections just need a 100watt iron, and electrical tape it up.
Attachments
tmp_14415-IMG_20170205_140129-1955745111.jpg
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Re: Plasmagun/railgun for Stelarate

Postby Dennis P Brown » Mon Feb 06, 2017 12:14 pm

As I posted before and as others are now indicating, a safe "shorting stick" is very important to both check that the system is safe (fully discharged) and to enable you to discharge the system in the event of an emergency. That is, a long plastic stick with a metal end (metal screw or pointed rod) with a fairly high current (proper gauge) well insulated (for the voltage) wire connected from that tip to a ground (the same used for the cap bank is fine as long as it has been checked - i.e. is a good ground.) I have one of these for both my fusor and accelerator (its voltage multiplier.) I never touch any part of these systems without first checking them with the ground stick.

Another important safety issue - caps that are rapidly discharged can over heat and explode. Shielding and proper safety eye wear is essential, too.

Those exposed rails on those banks are death traps just waiting to happen and you will very much need some type of stand off shielding for those rails if I am reading your picture correctly.

I see no issues with you getting a plasma in the 20,000 K range at a few hundred amps for a fraction of a second; that said, the ability to accelerate deuterium to any type of significant fusing velocities will not be achieved with such little power and low voltage (building a small accelerator would do far better.) Even a high end neutron detector system would not measure any signal with such a low velocity plasma. However, you are mistaken if you think an atmospheric system will support a plasma that allows increased "mean free path". Sorry, but the only way to change that parameter is to significantly lower the pressure (in the range of 10^-3 torr or more.)

You have some good experience with caps so a voltage multiplier shouldn't be too difficult (getting a 50 kV, high current (for a small fraction of a second) system isn't hard to build (but isn't cheap, however, unless one gets a good deal on the caps but that is another issue.)) The very high vacuum system is another matter and may not interest you for a small accelerator so that might not be for you; however, that, in essence is what you appear (from my read) to be attempting to achieve - accelerate deuterium - with this current system. That will not work at all with such a low voltage much less at atmospheric pressure.
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Re: Plasmagun/railgun for Stelarate

Postby John Futter » Mon Feb 06, 2017 6:05 pm

At least you are using micrpwave oven capacitors that have an in built high value shorting resistor
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Re: Plasmagun/railgun for Stelarate

Postby Andrew Haynes » Wed Feb 08, 2017 3:59 am

Hi, I entered the data on hyperphysic website for the mean free path, at standard temperature compared to 20kK was a 100 magnitude longer, lowering to 1kPa at the outlet, should get the length enough, with the voltage drop around the coil ,parallel, should or maybe accelerate it enough.
I don't want to make 50kv, or 220kv.
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Re: Plasmagun/railgun for Stelarate

Postby Dennis P Brown » Fri Feb 10, 2017 10:59 am

You do realize that the room temperature mean free path is on the order of a nano-meter so increasing it by just two orders of magnitude isn't very much - 100 nm isn't very significant - and really, since the plasma temp isn't uniform (only a very narrow region reaches those temps), your average ion mean-free path is going to be much shorter. So, what do you think will be the result of your atmospheric (atm) pressure arc in air will achieve?

Aside: Don't use such an arc in hydrogen/deuterium gas at atm pressure! This class of gas is very explosive if oxygen is present in any moderate to even minor amounts (as for arcing H2/D2 in the atmosphere, that could prove highly dangerous for even small amounts of gas! Also, H2/D2 burns with nearly an invisible flame.) Also, even in pure H2/D2 a dangerous over pressure can occur in a sealed container by reactions and also from the temp induce pressure spike of an arc. In a fusor the pressure is 10-6 atm so D2/H2 isn't gonna create problems (and the trace oxygen levels are far lower still.) DO NOT ever expose H2/D2 at or anywhere near atm pressure with arcs!

Have fun but do remember safety is paramount.
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Re: Plasmagun/railgun for Stelarate

Postby Andrew Haynes » Sat Feb 11, 2017 4:16 am

This is the prototype that I will be using.
Data

Code: Select all
H value ????
Volts.     uF.      Bv.       Nogap       vp
?            1.5a.    9kv.      1.              1 m/sec,a


a = approx.


Things I noticed, potassium ion are quite conductive. There's a lot of back pressure in a pipe. With a magnetic the positive ion travel one direction compared to electrons, that's different from salt water.
Attachments
tmp_21376-IMG_20170211_170439-1955745111.jpg
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