Over the past few weeks the department overhauled the lab and the contents.  Bill and Jonthan, my two advisors, went out and purchased a spot welder, air torch, and tons of misc tools.  The lab is really looking spot on now.  I believe we’ll be able to build everything key to the project.

Also,  all the vacuum equipment, including the chamber and the pump,  have come in.  Check out the lab:

The lab as of now.

Our chamber is in:

The chamber, pump, and HV supply.

We pumped out a tube, not the chamber.  We got an ultimate pressure of around 2.8 mTorr.  This is great!

2.8 mTorr final pressure.

Should be assembling the chamber in the next few days.

-BK

It has a top end of what we expected after testing it to only 85%.  The reason why we don’t have data for 85%  and up is due to coronas.  Corona shouldn’t occur on our actually chamber, which will allow us to get to 18KV.

Our advisor, Jonathan, also bought a 30KV supply that won’t put out as much current as the BAX-30-70-NRL.

Bertan 825 30KV Power Supply.

Can’t wait to test out the supplies and make some plasma.

-BK

The last month has been used to mainly discuss how the vacuum chamber should be built.  There’s basically a few main geometries that we could chose from.  On the fusor forum, there’s one predominate style: spherical.

Ignore the nubs; see how the main body is spherical?

The spherical chamber has a few advantages.  Firstly, it simplifies the whole thing.  There only needs to be one grid, the inner one.  Secondly, its spherical design allows for tons of ports to be added to it, which means more data, instruments, or experimentation.  The disadvantages are that if the device was to be used by a future classmate it would be hard to adopt it.  Also the spherical chamber would have to be professionally manufactured which would take about 6 weeks and 1000 dollars.

Although we have the money, we don’t have the time.

We eventually designed our chamber off of a “4 way cross”.  The design will not be as easy to assemble as the spherical chamber, but we’ve come up with all the solutions.  Our design was heavily influenced by the University of Wisconsin’s IEC device:

Our chamber, created in auto cad with the help of the Kurt J Lesker drawings. Named the Gol3tron after our good friend, Adam Goler.

Compare it to Wisconsin’s design:

Wisconsin has a very similar design for their chamber, just bigger, badder, and more precise.

We also have started buying things.  We picked up a pump for 200 bucks thats good to 10^-4 Torr and a high voltage probe.  Hopefully we will start building the chamber next week.

Updates in the next week.

-BK

My 30,000 Volt 70 milliAmpere power supply I found in the "morgue" of the physics department

I have recently started testing the 30KV DC power supply that I have via a high voltage divider circuit. Its fairly old (1979), but has been sitting dormant for I would say a decade or so.  Its hard to believe that its almost 10 years older than I am and still working.

The front of my supply with all the gauges visible.

The power supply has a positive, transit, and negative polarity switch, adjustable input voltage which regulates the output voltage, a DC Limiter, and meters for both voltage and current.

What a Frakenstein power supply.

Here’s the back of it.  The coolest part is that the polarity of the voltage, positive or negative, is easily reversed via a piece of acrylic on the back:

The reversing mechanism.

Just pull it out and and twist it ninety degrees and you can go from negative to positive polarity.

As I test it I’ll post the results.

-BK

A fusor is a device that uses high voltages to confine and collide particles, as I’ve said before.  It does this by having two things:

• High voltage power supply and high voltage spherical grids.
• A vacuum chamber and a vacuum pump.

Here’s the schematic from the variant I will be making, the Hirsch-Meeks fusor:

To construct the device you start by getting a spherical stainless steel vacuum chamber such as this:

The Zambelli Fusor. All the knobs on it are addons to the vacuum chamber such as a high voltage feedthrough.

Inside of the spherical chamber is a tinier grid.  It looks like this:

The tinier inner grid attached to a high voltage feedthru.

The inner grid gets charged to -30,000 V DC and  the stainless steel spherical vacuum chamber gets grounded.  The resulting voltage in the chamber looks like this:

The potential well of the fusor. Particles roll in from the top, move over the bump in the middle, and collide dead center.

A top down view of the inside of the potential well. Notice the chimney, which is caused by charged particles which have been confined to the center.

Notice how it looks like a hill?  Its a hill for electrically charged particles!  They all roll down the sides and collide in the middle.  Its known as a potential well.  By decreasing the voltage on the inner grid (making it more negative) the hill gets steeper.  If the negative voltage is high enough, the walls are steep enough the particles will be moving at about 2,000,000 meters a second.  Yes, that’s really fast around 1% the speed of light.  At this point we can measure the particles in temperatures instead of speed.  The temperature is around 400,000,000 Kelvin or 719,999,540 Fahrenheit.  Its hot.   The last thing that needs to be done is reduce the pressure.

Two stage vacuum pump.

A vacuum pump can be used to obtain pressures low enough to allow thermal electrons to ionize most of the gas giving you a plasma.  The end result looks like this:

Brian McDermott's fusor in action. Notice the star of gas confined to the center!

More confined gas with an e-beam jet coming out of it in Richard Hull's fusor.

These are the results I hope for.  These can be obtained with regular air.  But, to make fusion, you need Deuterium, which is special hydrogen.  By inserting it in the chamber fusion reactions can occur numerously at around -26,000 V.  This will be our last step in the process, although just making confined plasmas with air would be great.

The next posts should be shorter as they will just update you with the progress we’ll be making.

-BK

Around two years ago I became interested in a scientific project that allowed amateurs to perform nuclear fusion, for a modest price.  This was during my sophomore year of college at American University.  Now that I’m in the last semester of my senior year  I feel comfortable that I can properly construct one of these

devices myself.  This device is known as a ‘fusor’.  It was originally created by Philo Farnsworth (the inventor of the television not the professor from Futurama).  For a scientifically unsavy person a fusor can be a little complicated.  Here’s the short version:  A fusor uses electric forces to confine and shoot ions.  Ions are just atoms that have been stripped of some electric charge; they’re not electrically neutral.  If the fusor shoots the ions hard enough, they can collide together and start a fusion reaction.  Wait!  Stop right here!  Disregard anything you have ever heard about fusion.  No, there is no such thing as cold fusion.  No, fusion is not science fiction.  Yes, fusion has been done on Earth before (a lot infact!).  Let me explain a few things to you so you can understand what we’ll be doing and how we’ll do it.  Well get back to the fusor in a bit.

100% Badass Chemist/Physicist

Over one hundred years ago a physicist/chemist named Ernest Rutherford was experimenting with fundamental nuclear particles, called alpha particles.  Rutherford was to shoot the particles at a peice of gold foil.  The hypothesis was that the particles would be slightly deflected as they went through the gold foil.  Dr. Rutherford did see this, but he also saw the alpha particles deflect in huge angles due to what we now know was the atomic nucleus.

Enrico Fermi proudly displaying the Schrodinger equation.

Fast forward around thirty years.  A physicist named  Enrico Fermi came up with the crazy idea that the atomic nucleus of big atoms were unstable.  He postulated that the nucleus could be broken apart under the right conditions.  Specifically he though that a special atom, Uranium, could be broken if a he shot it with a neutron, an electrically neutral particle.   It turned out that he was right.  The process of breaking a nucleus was deemed a fission reaction.

How fusion occurs in the sun. It takes four hydrogen nuclei.

Shortly after the fission reaction it was realized that there was another nuclear reaction: a fusion reaction. Instead of breaking a nucleus, fusion requires two small nuclei to come together and join.  This reaction is considerably harder to perform because in physics ‘opposites attract and likes repell’.  Whenever two positively charged nuclei try and come together and join  the electric force says NO!  But, get them close enough and another force, the nuclear STRONG FORCE, pulls them together.  Fusion occurs!

Fusion has been occurring in labs since the 1930′s.  The oddest part about it is that you see fusion everyday, or should I say night.  Stars are producing heat and light because of fusion.  Another example of fusion was the hydogen bomb Ivy Mike.

Fusion releases a whole bunch of energy when it happens.  The problem is keeping it under control and harvesting it.  Scientists have devised many complicated ways of confining fusion.  One way is through a doughnut shaped device called a ‘tokamak’.  To the left is a tokamak in Korea that is running.  The blue glow is from plasma.  What is plasma?!

The trademark pink glow of hydrogen plasma in a tokamak. Notice how its not touching the walls: its confined!

When atoms are heated, changes in phase occur.  A common phase change is when ice melts into water.  Another common phase change is when water is boiled into steam, a gas.  Another phase change can occur when a gas is superheated.  This phase change turns a gas into a plasma.  Heating a gas requires special techniques, but the most common way is by using high voltage electrons to `knock’ into the gas atoms, therefore heating them up. This is called ohmic heating. When the gas atoms have enough energy they ionize, and the atoms’ electrons are not bound the nuclei anymore. A side effect of the nucleus being stripped of its electron is that it loses its electrical neutrality; it can react to an electric field, which in turn can provide a force on the particle.  Plasmas tend to glow due to hot gases giving off energy in the form of light.