Milestones and Progress: Cade Neely Fusor Update

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Cade Neely
Posts: 28
Joined: Mon Dec 30, 2019 9:06 pm
Real name: Cade Neely
Location: Southern Indiana

Milestones and Progress: Cade Neely Fusor Update

Post by Cade Neely »

Here is the update on my fusor progress as promised in my plasma submission. It has been a long, exciting (and slightly infuriating) journey. My system has gone from a fully functioning, remote-controlled vacuum system to a remote-controlled demo fusor. Let’s cut to the chase! Here’s the progress.

X-ray Transformer High Voltage Power Supply:
After I completed the vacuum system, I moved on to constructing a high voltage power supply. I decided to build it around an x-ray transformer that is controlled by a variac. The output of the transformer is rectified using a full bridge rectifier. The maximum I have pushed the system to is 5kv at 12ma. The reason I have only pushed it this high is because I suspect there is a short on the secondary. As I push the voltage higher, my variac starts pulling 8amps at 15v output. The high voltage components are located on the cart and were originally controlled at the cart. This power supply has been very useful as it allowed me to experiment and achieve plasma. In order to do fusion, I purchased a 20kv 7.5ma power supply at HEAS. While this supply will produce weak fusion, I plan on purchasing a neutron detection system from Maximus Energy in order to prove fusion.

High Voltage Feedthrough:
My high voltage feedthrough was inspired by a post from Liam David. It utilizes a compression fitting with a teflon ferrule to seal the quartz glass tube. A 1/8” stainless steel tube acts as the conductor and is attached mechanically using a large nut that rests on top of the tube. It is attached electrically to the compression fitting using a copper spring. The conductor is insulated as it passes into the vacuum chamber by an alumina stalk which allows a screw to be fed through. The molybdenum grid is attached to this screw. I chose molybdenum because of the price and rarity of tungsten.

Remote Operation:
Almost every system of the fusor so far has undergone two phases: construction and testing of that system, and then construction of the hardware necessary to control and monitor it remotely. This has added a whole level of complexity to the project but has been very rewarding. With my vacuum system, remote operation was controlled by the auxiliary electronics module. Remote control of the high voltage power supply was much more simple. As I stated earlier, the x-ray transformer and associated high voltage equipment is located on the fusor cart with the variac mounted on the cart as well. For remote operation, I mounted the variac inside my control panel and then ran wires to the cart, supplying the transformer with power. Powering the transformer proved easy, measuring the output was a different matter altogether. My voltage and current meters are 50 microamp analog meters. As such I had to find a way to transfer the power being produced to the control panel with minimal losses for accurate measurement. At the high voltage output of the rectifier, I installed a tap leading to an oil immersed 100 mega ohm resistor string. This was fed overhead via a wire to the “voltage meter” located at the control panel. This wire was the positive and the negative of the meter was connected to ground. The current meter is connected to the negative of the power supply and the other side of the meter is grounded.

Throttle Valve Control:
In order to control pressure remotely I installed a stepper motor on the valve between the turbo and backing pump. This was before I had completed the gas input system and as such, I was not running the turbo. This arrangement allowed control of the pressure in the chamber by throttling of the backing pump. This setup has since been removed as I am currently working on the upgraded valve that will throttle off the turbo when it is running.

Gas Input System:
The gas input system is composed of a quick connect fitting, needle valve, 1/8” stainless steel tubing, and compression to kf to conflat adapter. The quick connect fitting allows for easy connection and disconnection of gases.

Argon Plasma:
After completing my gas input system, I was eager to try argon plasma. First, I did a normal air run to test the system’s operation. After the test came back successful, I went for argon. The argon cylinder is mounted on the side of the cart and anchored down with a strap. I used a flow meter regulator for lack of a pressure regulator. The run was very successful with the only disappointing fact being the the plasma was not as blue as I thought.

Conclusion:
I am very pleased with the rate of progress of this project. It finally seems that fusion is in the not too distant future. The next steps are remote control of vacuum throttle valve and needle valve, achieve high voltage levels capable of fusion, installation of shielding, and neutron detection.
Attachments
Early Stages of Testing the HV Supply
Early Stages of Testing the HV Supply
Early Power Supply Setup
Early Power Supply Setup
HV Remote Operation Setup (Demo fusor setup)
HV Remote Operation Setup (Demo fusor setup)
HV Feedthrough
HV Feedthrough
Feedthrough Components
Feedthrough Components
Partially Assembled Feedthrough
Partially Assembled Feedthrough
A Highly Improvised Throttle Valve
A Highly Improvised Throttle Valve
Argon Cylinder
Argon Cylinder
Compression to KF to Conflat Adapter
Compression to KF to Conflat Adapter
Needle Valve and Quick Connect
Needle Valve and Quick Connect
Stainless Steel Gas Line
Stainless Steel Gas Line
Argon Plasma
Argon Plasma
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