nuclear fusion A quality high vacuum chamber is required for = Pade \ aa appropriate chamber can be found оп eBay, Я у Pe but generally it is best to make one. Parts can > a 2. be scrounged for severa

nuclear fusion
A quality high vacuum chamber is required for = Pade \ aa
appropriate chamber can be found оп eBay, Я у Pe
but generally it is best to make one. Parts can > a 2.
be scrounged for several hundred dollars, ог <a ` » РЯ
purchased new for $500+. Somers — у
Get two stainless steel hemispheres, purchase Sas > СУ. g 86
two corresponding conflat-flanges (8" flanges Sy 74 вт
in my case), Боге out holes for accessory Е Е nr
flanges, and then TIG weld it all together. Bd If 55 Se, :
conflat style. Conflat can be seen т the image ры 5 и: ва
below as the flanges with bolts, and KF (kwik- дах “ff? bon
flange) are seen as those with only clamps че А г
holding an o-ring on the mating surface. Only a G RS SaaS
weld on the inside, never on the outside (since har т №
virtual leaks can be formed if both inside and
outside are welded). If you've never TIG
welded before, it would be wise to have 2
someone with experience do it as the welds ь $
must be flawless with no pin-sized holes or .
porous areas to hold a vacuum. ь
After machining, thoroughly clean the Ms
chamber and avoid getting fingerprints in it >
since these will outgas, which means at | ®. )
vacuum pressure molecules in the oil of finger Se
prints or machining oil will become vapor and
make it hard to maintain plasma stability or
reach a good ultimate vacuum level.
The inner grid (where the high
voltage is applied) must now be
built and attached to a high
voltage feedthrough.
tungsten for the grid wires since / .
it has a very high melting point, j
hot during high power runs. У, ~
cordless drill, the only thing you really can't build without a shop
spherical shape of roughly 1-1.5 р
inches т diameter (for a 6-8"
chamber), it should work fine.
The grid should be internally 5
attached to an electrical
pictured т the second image. _ 2%
This feedthrough needs to be ON,
rated for the cathode voltage
is a good target voltage.
If you can purchase а power supply
(occasionally but not commonly found —
surplus) appropriate for fusion use, the na as _——.
high voltage becomes very simple. Simply Г «.—аэ—
take the output of the 40kv negative
physically large high voltage 50-100k ohm a /
ballast resistor in series (large enough Bs р ‘bs =
that its length will not flash-over if 40kv is ed tae Saban —
The difficulty is that it is often difficult if )
not impossible to find an appropriate fully
assembled DC supply of this voltage level las
that is affordable to the amateur scientist. |
Pictured is my high frequency ferrite Бе и
transformer pair, with а 4-stage multiplier fe ug Т }
If a fully assembled power supply 7 | 4 | a j
(typically manufactured by either г * | | Fr
necessary either reverse the rectifiers for ы
negative polarity or add rectifiers if К has = ©
have rectifiers, it probably will И it is т its \ $
power supply. This is what | did, however = =
several aspects must be resonant and if it - = =_= } Е
is ever taken out of tune, the transistors р
will burn out. Probably not the best option
for people with little electrical
Time to turn it on (don't forget to cover any
viewports/cameras with lead! Also x-rays can —
pour out of ceramic feedthroughs so point them
monitoring for x-rays where any people are
present). The basic procedure is: =
sufficient backing pressure, turn on the diffusion и .
or turbo pump and wait for it to fully warm up or >
achieve running speed
-Throttle the chamber back (with the valve
Install the oil diffusion pump (or turbo р
-Ever so slightly open the needle valve to the
-Turn up the high voltage until either plasma
you only get one chance т your life to screw up ч
with voltages of this degree)
-И nothing has happened, keep admitting more
gas and the pressure should keep going up.
Plasma should form around 40kv at about 10-15
microns of deuterium.
If all goes well, you should see on your camera
the image below, and you should be detecting у) Э
neutrons at this point.
Operation is quite a balancing act, since the devterura
voltage is controlled by both the power supply,
after doing so it becomes quite simple to run.
-A roughing vacuum pump capable of reaching at least 75
vacuum to reach at least 75 microns.
-A secondary high vacuum pump, either a turbo pump or oil
-A high voltage supply, preferably capable of at least 40kv 10ma -
-A high voltage divider probe for use with a digital multimeter
-A thermocouple or baratron (of appropriate scale) vacuum gauge
-A neutron radiation detector, either a proportional He-3 or BF3
tube with counting instrumentation, or a bubble dosimeter
-A Geiger counter, preferably a scintillator type, for x-ray
-Deuterium gas (can be purchased as a gas or extracted from 020
through electrolysis - it is much easier and more effective to use
-A camera and TV display for viewing the inside of the reactor
-General engineering tools, a machine shop if at all possible
(although 90% of mine was built with nothing but a dremel and
is scratch building the vacuum chamber)
the fusor to operate. Sometimes ап ~— ye < %-
scrounging or a higher budget). Fill the | BAS :
whatever fill level the pump — — ~ ;
documentation suggests, attach the = Vy 7
inlet to а valve which then connects to | Yj, : wa’ №
the chamber (see diagram), and attach Ир >
the outlet to a mechanical backing pump Я \, $ — -
pump will not operate properly or the oil } N
will oxidize quickly). > а
cooled, many oil diffusion pumps
require water cooling, smaller ones
pump by turning on the boiler on the attain Plame:
diffusion pump. After it warms up (could
take a while), the vacuum should rapidly Mechanical bump
drop below the single micron range. a i