Fusor Mk. II Progress

It's been a while since I've written, school and other commitments have continued to devour my free time.
It's good to be back.
Since I left off with my last post on my Mk.II reactor, I have made much progress. I have had the chamber machined, gone through two different power supplies, acquired a bottle of deuterium, and gotten an ultra high vacuum system working.

Before I go into any more detail on my current apparatus, I'm just gonna recap how the fusor works in Layman's terms:

The vacuum chamber is pumped down to a very low pressure, and a high negative voltage is applied to the inner grid, which is a spherical electrode in the center of the chamber. The outside of the chamber is left grounded. Due to electrostatic field emission from the grid, the gas in the chamber is ionized, forming a plasma. These gas ions are positively charged, and due to the inner grid's strong negative charge, they are accelerated towards it. In the center of the grid, some of the ions collide. If the gas in the chamber is deuterium (hydrogen-2), the two colliding deuterium nuclei will fuse into a helium-3 nucleus and eject a fast neutron. The nucleus then will remix with electrons emitted from the grid and become neutral.

Just to start off, here is a picture of my current setup:

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Now for a quick walkthrough of the different sections of the reactor...

The Chamber:

 The reactor's stainless steel, spherical chamber was machined with the help of Tom Egan at Mercury Machine Company's machine shop, and my deepest thanks goes out to them, I really couldn't have done this without their excellent work. The chamber has a 1.5" wide viewport, a high voltage feedthrough port, a port connecting to an air cooled diffusion pump, a 6" long tube for a future ion source, additionally, there are two 3/8" NPT ports on the top of the chamber for vacuum gauging and a soon to come gas system. The flanging on the chamber is a mixture of commercial and custom hardware. Both the pump flange and the feedthrough flange are ISO-esque flanges in which an o-ring is pressed against a flat plate, forming a seal. The 8" diameter flanges holding the halves of the chamber together, as well as the 2.75" flanges on the ion gun tube and viewport are conflat-type flanges. In a conflat flange, a copper gasket is pinched tightly between two "knife edges" on either flange. This creates a very strong seal between the flanges.

High Voltage System:

Originally, I had planned to use an x-ray transformer to power the fusor, and later I decided on using a two stage, lines frequency voltage multiplier to run the reactor, constructed of 2 stages of 2 banks of 16 microwave capacitors, driven by a few neon sign transformers (In the future, I plan to use this supply, however with a distribution transformer powering it). However, recently, I was graciously given a 30kV Glassman high voltage power supply, which I currently am using to power the reactor. The
supply uses a simple D25 connector to interface with a simple controller I made for it.

The Vacuum System:

The fusor's vacuum system consists of two pumps, a rotary vane mechanical pump, and a air cooled, oil diffusion pump. The mechanical pump first pulls the chamber down to a pressure of around 160 millitorr -1/4750th of atmospheric pressure. At this point, the diffusion pump is turned on. A diffusion pump is a type of  ultra-high vacuum pump that uses fast moving heated oil to pump a gas from a chamber. The diffusion pump will bring the overall system pressure down to less than one millitorr of pressure. The diffusion pump can be throttled by a variac that controls the oil heater's voltage.

Pictures of Runs: 

Three loop grid, pressure around 10 millitorr

Two loop grid, pressure around 5 millitorr

Toroidal grid

High Speed Videos of The Air Cannon

I recently shot a couple of videos of my air cannon and put them in a compilation. The camera used was a casio Exilim Fc-100.

Enjoy

Fusor Mk. II: Update and Plans

It feels nice to be writing again. Since my last update I have acquired a 75kV x-ray transformer, as well as all the parts to make my vacuum chamber. I also got a Veeco EP-2A air cooled diffusion pump. Inconveniently, both this pump and my HV feedthrough require custom flanges to be machined. The plans for my new chamber are below.

In the plans, the HV feedthrough port is the lower left one, the diffusion pump port is the bottom middle one, and the long one on the bottom right is an ion gun based on a DC magnetron, which is not shown. The DC magnetron is unlike it's cousin, the cavity magnetron, which creates microwaves, whereas the DC magnetron helps ionize gas by setting electrons into a spiraling path. Inside the source, there will be a 6"x1/4" rod charged to 3-5 kV. The magnets will surround the source partially, or I will use a large electromagnet wound around the source.. The 30kV will be generated by a 15kV NST (floating center tap) run through a voltage doubler constructed of microwave oven capacitors and diodes.

I have also decided that I will leak deuterium into the chamber through a 5 micron wide orifice on the ion gun. The deuterium will first be regulated down to 5 psi from tank pressure by a hydrogen regulator, and then it will pass through the 5 micron orifice and through a ball valve.  

To detect neutrons, I will be using a much cheaper approach than the normal bubble dosimeter or a He-3 or B-10 tube. I will be using a cloud chamber to view proton recoil from neutrons as they pass through a hydrogenous moderator. The chamber will be lead shielded, allowing only strong cosmic rays and neutrons to pass into it. There will be a piece of LDPE inside the chamber to allow for the proton recoil to occur. Below is a picture of proton recoil tracks in a cloud chamber.

Fusor Update and Pictures

Sorry I haven't written for a while, but the science fair and school have completely consumed my life.

This is just a quick update on the fusor. 

I am currently upgrading my vacuum system and and adding in a diffusion pump, which is a type of high vacuum pump used in series with a mechanical pump, this pump should allow me to reach pressures of less than 1 millitorr. I am also going to build a 50kV/5mA power supply, which should allow me to do fusion. I am also building a 6", spherical stainless steel chamber, complete with conflat high vacuum flanges, a nice high voltage feedthrough, an ion source operating off the magnetron principle, and a nice viewport.

Recently, I also entered my fusor in the science fair as part of a project titled "Effects of an Outer Grid on an Inertial Electrostatically Confined Fusion Reactor", and I received many awards! 

I received the following awards:

• Mars Society Grand Prize
• 1st Place in Physics at the District Science Fair
• District Fair Grand Prize 
• Superior Rating at Districts
• Akron Council of Engineering and Scientific Societies Grand Prize 
• Bridgestone America Best Physics Project
• 2nd in Physics at NEOSEF
• Superior Rating at NEOSEF
• The Office of Naval Research Naval Science Award
• International Society of Automation Grand Prize
• Superior Rating and Perfect Score at Ohio State Science Fair (no prizes like 1st 2nd or 3rd were given out)

I also received a perfect score at states, meaning my work will be published in the Ohio Academy of Science's Publication. And I will attend a Junior Academy of Science Conference in D.C. 

Me at states in front of my project

Now for some pictures of the fusor, these were taken during, or just prior to, it's last run before being critically damaged. 

This picture is my favorite, makes an excellent desktop background

Another one of my favorites, camera is looking down an e-beam

Yet another of my favorites

BIG bugle jet

Great Starmode with Ion/Electron Beams!

Currently, the fusor is broken, due to a broken bell jar. But, prior to it breaking, I got a great starmode out of the fusor! I found that scaling the inner grid down allows for this to occur. Pictures are below. :) The fusor will be fixed soon with a metal chamber.

Video of the Fusor

Here's a video of the fusor running. I built a new rectifier and the NST can now exhibit its full potential.

How the Fusion Reactor Works

I have received many questions about how exactly my reactor operates so here is a post explaining it. I may make a video for those who more easily grasp concepts when images are provided.

The concept of fusor operation is much simpler in theory than  in execution. Basically, I pump the bell jar down to a high vacuum, charge the inner electrode (outer one is grounded) to a high negative DC potential.

Field emmition from the grid causes the gas inside (air for non fusion, deuterium (2H) for fusion) the gas ions, as they are positively charged, are accelerated towards the negatively charged inner grid. They carry enough inertia to continue past the grid wires and collide in the center.

The remixing of ions and electrons creates the plasma discharge.

No more Fusor for a little while/What's coming up.

Sorry, but there won't be many fusor posts for the next week or two due to some minute electronics issues. However, my CDV-700 geiger counter is on it's way, and I plan to do a review on it.

Here is a recent pic of the plasma star.

Star Mode-Achieved!

Finally, with a new grid based off of interlocking washers, I have achieved "star mode" from my fusor. This occurs when plasma jets, electron, and ion beams emanate from the plasma at many points inside the inner grid.

The ground fault protection on my neon sign transformer fires rapidly (I desperately need a new NST) when operating in this mode, rendering it hard to get a good picture of this. My best efforts are shown below.

New Inner Grids!

Here are some new inner grids I made:

Heres a nice spiral torus shaped grid

And, because of valentine's day, why not a heart shaped grid.

Fusion Reactor's First Light!

After about 1000 hours of work and research, halon fire extinguisher in hand, donning my lead jacket...I flipped the variac's power switch, turned its knob, turned the ground fault protection off, and frankly, much to my surprise, a brilliant glow of blue plasma appeared. Yup, it works. The next step after this is to move on to fusion by upping the input voltage and building a deuterium injection system. To find out more about how this type of reactor works go here: http://en.wikipedia.org/wiki/Fusor

Heres a picture of the fusor's control panel

Here are the oil filled cylinder's containing the circuit boards..in this picture they aren't completely hooked up.

Here are more pictures of the plasma:

The Rubberband Minigun

I build this a couple summers ago just for kicks, to challenge myself. It is a 6+ foot long minigun (gatling gun) that shoots industrial sized rubber bands at rates of up to 60 bands a second. Theoretically, it can hold 2000-3000 rubber bands, but, for the sake of my sanity, this has not been tested (reloading is a slow process). The gun works by stretching rubber bands around pegs with a slot in them and then running a ribbon through the slot, when the ribbon is spooled in, the barrel spins, and the ribbon is pulled out of the slot, thus firing the rubber band. The gun Is powered by a cordless drill.

Coming Soon!

I am in the middle of building a Farnsworth Fusion Reactor. I will get around to posting it soon, I am a bit delayed in my projects because midterms are fast approaching. In the meantime, to learn more about what exactly this is, visit www.fusor.net.

10' Air Cannon

Well, I figured I might as well start this blag off with a quite literal bang. This is an air cannon I made about a year ago that fires projectiles at 800 feet per second. The barrel is 10' of either 1.5" or 2.5" PVC pipe and the chamber is a total of 10' of 4" PVC pipe (All the components on the cannon are pressure rated). This cannon doesn't use a ball valve or any other slow opening valve to fire, instead it uses a chamber sealing piston valve to quickly dump the air pressurized  to 120 psi in the chambers out the barrel. The effects of all this energy imparted on a tennis ball or arrow are quite substantial, as evidenced by the video below.(+1 Internets if you caught the XKCD reference.)