This is Hacker Public Radio episode 3,739 for Thursday the 1st of December 2022.
Today's show is entitled, Multipactors For the Masses.
It is hosted by one of Spoons and is about 26 minutes long.
It carries an explicit flag.
This summary is, seemingly advanced artifacts of one's locale are tangled whims upon
exponential inspiration.
Hello Hacker Public Radio.
This is one of Spoons.
To give my brain a rest, I'm going to channel someone else today.
I've been working on a few other shows, but in order to get a show in quickly, I thought
I would transcribe an old video manuscript that's been lying around in an old partition somewhere,
which impressed me at the time.
The audio quality was very bad, and although I'm fairly sure the speaker would have not
mind if I passed on his lecture in its entirety.
Thought it might be more straightforward to transcribe verbally his talk easier than getting
my head around composing editing my own show.
I did transcribe that audio in my noisy server in because it was warm and comfortable
in there, and that's where the video was.
I did apply audacity noise reduction, which took care of the 6 or 8 head dryer noise
is coming from my server, but bear in mind, my voice still sounds like I'm talking over
something, but it's not too bad.
I did cut out about 10 minutes at the beginning, which is a potted history of nuclear
power, fish and power stations and their problems, and then moving into a talker mac research,
a talker mac, I think is a Russian word for a magnetic bottle.
On the whole, I do trust this fellow to get his numbers correct, I did check a few of
them because they sounded large, very large.
He has been known to make a joke, but I don't think this is a joke.
At least not in the regular definition of a joke.
The speaker was Robert Murray Smith, and his subject was a table-sized fusion power generator.
So enough of me already, here is the story.
In order to get a nuclear reaction to happen, what you need to do is get enough of the
reactants together, act the sufficient density, and you need to direct them towards each
other at the correct angle and with sufficient force, because the nucleus has a force of
repulsion due to positive nuclear forces, protons having a positive electric force, and
neutrons being neutral, the electrons are not in the nucleus, they're around it, and they
have those negative charges.
So the nucleus is, will only get so close before they'll repel each other.
The simplest example being two protons, two hydrogen atom ions, like without their electrons,
an ion is a charged particle, and its charge will be the difference between its positive
and negative charges.
That repulsion is called the Coulomb force, in order to get our two protons to fuse together
to form helium, we need to overcome the Coulomb force.
When that force has been overcome, then the protons will be fused together and held together
by nuclear forces.
You will need a fairly direct hit.
If you direct particles off-centred, then they will deflect, and that's the difficult
part.
There is a formula, you need the density of each reactive species, and then sigma f, which
is the cross-sectional area, and we factor in the velocity of the collision.
The product of all of those factors is the likelihood of the reaction occurring, like the
ability of the reaction to occur.
So to illustrate the formula a bit, we have reactive species, we've got particles, we've
got the density, like how many you can get in the smallest space, or within the space
over which you have any influence, and then you have the velocity, velocity being a vector
speed, that's speed, with direction.
The tokamaka approach seeks to increase the velocity of the particles by heating them up,
giving them energy by heating, which is apparently a very energy-intensive way of increasing
velocity, and bear in mind, these particles are charged particles.
So we do have ways of accelerating them, which we've known about and used for many years.
For example, if we populate a space with charged particles, and then introduce a plate of
material to which we apply a voltage, then those charged particles will accelerate towards
the plate, and the velocity of the particles will be related to the voltage.
Now let us relate temperature to velocity of a charged particle.
This is interesting, and electron volt is the speed of an electron towards a charged plate
at the voltage of one volt, one electron volt.
It is likely a familiar with the unit of the Kelvin, which is a unit of thermal energy, equivalent
to a unit of one Celsius degree, although those scales have their zeros at different points.
So roughly minus 273 Celsius would be zero Kelvin, and also zero ranking degrees, which
I hadn't heard of before, one ranking degree being equivalent to a Fahrenheit degree, and
ranking starts as absolute zero, and goes upwards in degrees ranking.
I'll be using Kelvin's, and one Kelvin is equivalent to 11,600 electron volts.
To illustrate this, if you are familiar with a cathode ray tube, the old television screens,
the particles, the electrons which would be hitting the inside screen of your old television,
would have an equivalent temperature of about 200 million Kelvin's due to the velocity
at which they're travelling.
So millions of degrees Kelvin are possible if you express them as velocity, remember electron
volts.
To enumerate our example, 4,200 kilovolts, so 4.2 million volts, mega volts, will give
us this 200 million Kelvin's previous century, an inventor named Phylo Taylor Farnsworth,
was working on valve diodes, so the valve diode is a vacuum tube with one emitting plate
and another plate in there, another charged plate, and this he developed into a multi-packter,
and from the multi-packter was developed to the fuser, which was a device to accelerate the
particle velocity to fusion velocity.
Please now engage your imagination, for the diagram is most simply a metal sphere or a metal
cylinder on the outside, which is positively charged, and then either a central point within
the sphere, which is negatively charged, or imagine a wire passing through the cylinder,
which is negatively charged with respect to the positive charge of your metal cylinder.
Dial up your potential difference to 50,000 kilovolts, so 50 mega volts, which we can do,
then we fire our charged particles, our positive ions, from the outside to the inside
to the negatively charged region in our center, and those charged particles will accelerate
into the center.
These charged particles speed into the center, and they will come out the other side a little
bit, but then the repulsion from the positively charged outer surface will drive them back
towards the negative center, to which they are already attracted, so fans with was accelerating
charged particles from all directions, and many of them, into the center where they would
aggregate, where they would be confined, and tend towards the negative charge in the center,
therefore their density increases greatly, as do the chances of collision.
You can describe the conditions at the center of this device as a potential well.
Apparently, fans with did achieve fusion with this device, some amount of fusion,
of course the physical implementation of that device had its limitations, or you could say it
expressed its excursion limits. If you recognise that sometimes people are doing things accidentally,
fans with implemented a wire grid as the central electrode, if you like, the negatively charged
electrode, to which were attracted the positive ions, so those positive ions were particles,
and they about 2% of the particles would collide with the wire grid, not make it
inside through their ginormous holes in the grid. So 2% of the kinetic energy of the positive
ions would be dissipated into the wire grid transformed into heat energy, so the wire grid would
get very hot. So that 2% of energy was enough to melt the wire grid within a few seconds, such
that the energy, the reaction energy inside was not enough to assume fusion. These devices are
called inertial electrostatic confinement devices. I could not make out the names very well,
but Hirsch and Mix were two other people involved in the development of fuses at that time.
Think spherical grids again, meshes, so you've got a central mesh, but polarity is reversed this
time. So a positively charged mesh sphere at the centre surrounded by some empty space and then
surrounded by a negatively charged mesh. So a grid within a grid and we surround all of this space
with a casement, a hard casement to contain our fuel. The fuel in this case was deuterium,
deuterium goes by the alias of heavy hydrogen and is one proton, one neutron, and the electron.
So ordinary hydrogen is just one proton, one electron. Double the mass similar electronic charges.
So if we've encased our deuterium in this system and we've dialed up the potential difference
between the two grids, then the positive ions will be attracted to the outer mesh grid,
allowing the electrons to be attracted to the central positively charged grid, electron mass being
so much smaller than the mass of protons, they are more easily controlled in these conditions.
More easily contained, relatively easy, of course, relating to the
high energies involved in this activity. Apparently what happens here and I've not to witness this
is the electrons become packed into the center of this device and create what is called a virtual
cathode, a core of electrons concentrated enough to then attract the positively charged ions which
had collected on the outer grid and pull them into the center and they do their overshooting and
then return to center, Cayley style traversal, while apparently not neutralizing themselves.
So the result is a cloud of electrons at the center, but then a densely populated area
of protons or should say positively charged ions because the neutrons are in there as well,
just adding density, apparently fusion does occur within this central core of
deuterium nuclei, nucleuses. This is on the record as reproducible, you might find some
pretty pictures, however that central grid still absorbs enough energy for this to be a non-viable
device from which we can extract a net energy, net useful energy. So at this point you might be
wondering how you can construct this situation without having a grid at all or having a grid which
cannot be hit by the electrons, since that's the obstacle. A person called Robert Bussard,
whom proposed a space engine, the Bussard ramjet, Bussard created a polywell
from a ring of magnets. The simple description given was that the ring of magnets was aligned
such that the electrons went around the magnets and were caught in the center well. So they could
not or did not collide with any physical barrier. The arrangement was difficult to engineer,
but Bussard died, I don't know how. The group which he created progressed to the project to
WB7. This video manuscript is about 12 years old and I've read in web pages just now that WB8
has been achieved since. The American Navy did take over this project. They might have officially
dropped it by now, a lot of time has passed and there's a lot more information online about
the developments ramifying from that project. Bussard reckoned he could get this working for
about $200 million and I did see that number written on a web page. If you take a look at the
budgets of some of these Tocamac projects and fusion projects nowadays like Cadurash in France
and of course American military budgets, you'll see that number is very small relative to
what they're spending on other things. Bussard had combined inertial electrostatic confinement
with Tocamac technology, the magnetic bottle technology. If you'd like to research that device
then search under Rigatron, Rigatron, but Robert Murray Smith at the time was keen on
a tangential method. In order to function and work safely, Tocamac's need to be surrounded by a
lithium blanket. The lithium blanket is about two metres thick and reacts with the particles which
are produced and escaped from the Tocamac producing Tritium which is fed back into the reactor.
Tritium is very rare. The Tocamac containment magnets were initially placed outside the lithium
blanket and Bussard's Rigatron had the magnets within the lithium blanket which yielded better
reaction results. Then Bussard took this further by putting the magnet arrangement inside the inertial
electrostatic containment device. Maybe if there's any advice to be derived from this many
lecture by Robert Murray Smith. Perhaps it is this. When people seem to run into hurdles,
big teams of people are huge projects and they all over the world use the same principles
thinking they can overcome these hurdles. Then either you think or are hoping that you can
overcome these hurdles or maybe take a couple of steps back to where the path diverged and see
what people were working on before they followed the path which appears to be blocked because
face it there a plenty of people trying that already. So maybe there was something close by which
escaped the attention of the excited researchers when they made a mini breakthrough. So Murray Smith
went back to Farnsworth's multi-packtor. The multi-packtor is an electron cascade device. Multi-packtion
is a problem for microwave engineers because it interferes with signals. So they tried to eliminate
multi-packtion. So maybe this is a case of utilizing sods law. Side note that might engage the
sense of humor of the universe and maybe all e-cout a few secrets as it chuckles back at you.
Engage imagination, not very much imagination, maybe concentration would be more appropriate
because the diagrams are very basic actually and tend to involve the same plus is minuses, lines,
curves, straight bits. Imagine a plate of material from which you can
emit electrons. You can shoot off electrons and those electrons you aim at another plate of material.
If you choose appropriate materials these electrons will be deflected back but will at the same
time produce more electrons from the second surface which will also scatter away. In the general
direction of your initial plate you're emitting plate. This is the cascade and those electrons
can cause yet more electrons to be emitted from whichever plate they collide with. Then you can
direct all of these or contain all of these cascading electrons with either magnetic field or an
electron magnetic field or electrostatic field. If you shape your emitting plates and bouncing
plates into some kind of parabolic mirror then you can imagine a situation where you have fewer
electrons to catch because most of them are bouncing towards another plate anyway. Apparently this
multipactor device of fans' worths would build up such an amount of electrons so quickly that his
laboratory would start to shake and his device would glow bright blue which is the point when you
know you're on to something. So he did what any level headed scientists would do and he dug a
30-foot well into which he could lower his multipactor device and switch it on until the place was
shaking too much. So this multipactor was a physical device. These parabolic mirrors are contained
in a vacuum tube. The electron flight time between the parabolic mirrors is specific. Therefore if
you know the distance between the parabolic mirrors and the speed of the electron and you divide
the distance by the speed then you've got the time it takes to traverse to travel the gap. Then you
can play at reversing the polarity of the mirror plates such that the polarity of the mirror that
your electrons are travelling towards is reversed and you come back off that plate and then reverse
the other plate before the electrons get there that kind of a situation. Your brain might be
recognizing the scene here. What happens if we switch the plates more quickly than the electrons
can reach the other side. So you switch the plates faster and faster the electrons which were
travelling to the other side in whichever direction they were travelling then switch to go back
before they reach the mirror and then eventually you can imagine there'll be going backwards and
forwards in the center of the device like in the space between the parabolic mirrors.
Some kind of little ball of electrons there. For good measure we can include
electromagnetic field around the device in the perpendicular plane to help form that ball of
electrons. So you can switch on your device in cascade mode generate a whole bunch of electrons just
bouncing around cascading from the plates making more electrons shoot out because they've been
energized such and then switch on your plates to oscillate such that the electrons fly backwards
and forwards and then don't have time to reach the other side and then have less and less time
to travel any further so they find themselves in the middle of your space in your device and then
who can put the squeeze on them with your electric magnet to push those electrons even closer together.
The difference between this device and the devices we first described is the lack of any grid
in the middle. We're not attracting the particles using a central grid but we have got
a ball of electrons which can now act as a virtual cathode so we just need to introduce some
ions so we can shoot those into the middle of the ball of electrons in the usual way.
You can heat up some emitter and positive ions so particles with positive charge no electron
but physical matter will be emitted and also attracted to this ball of electrons.
This is a situation which has been shown to produce fusion to generate the conditions
under which fusion does occur and Robert Murray Smith is standing in front of a squeaky white board
in a very echoey room in the distant past telling me distant this century telling me that this
device works better on a smaller scale like your kitchen table kind of a scale. Maybe even the
size of an old incandescent large bulb and the energy imports are not prohibitive they're not
too great. What about the tritium, very expensive, even deuterium not on the shelf at my supermarket?
Well those are chosen because they're very light so you can accelerate them
at greater speeds with energies which are not prohibitive so the higher the density of
something, the higher the mass rather then the more energy you need to give it to get it up to speed
up to fusion speed if that's the method you're using but Murray Smith is suggesting
boron 11 which is on the shelf in the borax. Boron 11 is about 80% of boron on the planet it's
a stable isotope in sea water about 0.005%. So multiply that by the ocean or pick up a box of borax
useful for other things if you collide a proton with boron 11, proton being the hydrogen ion
then you'll get carbon 12 and three alpha particles which does sound a bit alchemical but at
school I mostly thought it was only the transuranic elements that would be splitting into things
you know or making different elements of those three alpha particles one is a high energy alpha
and the other two are mixed energy alpha particles you will also generate some x-rays so have your
lead foil standing by don't keep it with the aluminium foil it's a different kind of poisonous
and if you know where I can get some tin foil I'd be very interested because I don't see
that in the supermarket either the high energy alpha particle has a specific speed specific energy.
Now where these high energy alpha particles to collide with a metal plate then they will absorb
two electrons we can make the side walls of our container from this metal and therefore have a
high voltage current flow through outer surface of our vessel no steam involves no heating
element no turbine just an electrical charge on the container vessel in case you missed the memo
and alpha particle is the nucleus of a helium atom so once the alpha particle has picked up
its electrons from the metal wall it becomes a low energy helium atom the helium atom is not
radioactive so the reaction products of this boron proton reaction are helium and x-rays and carbon 12
common carbon it is possible to substitute lithium for your boron you'll notice those
recipes listed if you go searching so this device is relatively safe compared to
fish and nuclear power stations which produce tons of nuclear waste even the fusion generators
have their radioactive products they're nowhere near as long-lived as the from the fish and
power stations but we're still talking generations of humans at the time Robert Murray Smith
made that video he was quite happy for people to contact him to join in a collaboration he didn't
think he could make this thing by himself and if you look at his other work he's obviously got
a lot of parallel projects many of them very accessible to the hacker and maker crowd this
old video as at least ten years old and I'm sure people have worked on this kind of a project
I've had a quick look and I've noticed old web pages describing a similar kind of thing I
didn't check the details yet but to you could if you were interested my show notes might include
some English words which you can search upon maybe one day I'll give you some nice show notes
but I still have dreams about struggling to finish my homework choose well folks don't get
electrocuted and don't spend too much time beside ginormous radio transmitters
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