Wednesday, November 7, 2012

Tuesday, November 6, 2012

Monday, November 5, 2012

Parts of the chamber

In a chamber, there must be a few parts in order for the fusor to work:
  1. High voltage feedthrough
  2. Viewport
  3. Grid

High voltage feedthrough

The hv feedthrough is what allows us to insert hv electricity into the chamber without disturbing the vacuum system. These parts can get very expensive, up to $1000 starting at about $100. Currently, I am using a automotive spark plug as my feedthrough because they are very cheap and require only a little bit of machining.





Viewport

 Viewports allow the spectator to view what is going on inside the fusor. In real fusors at higher voltages, these can be very dangerous because x-rays are released through them.

Grid

The grid is what is wired to the hv feedthrough attracts the air molecules it which are then ionized.

 -Not my grid-

The theory

A demo fusor requires a few basic parts:
  1. Vacuum system
  2. High voltage
  3. Chamber

The Vacuum system

A vacuum must be used to remove most of the air inside the chamber. The remaining air particles are ionized by the demo fusor system. Vacuum systems tend to become expensive so its important to keep your eye out on eBay. There are two main different types of vacuum pumping methods:
  1. Mechanical pump
  2. Diffusion pump

Mechanical pump

A mechanical pump is also called a roughing pump because it removes most of the air inside of the chamber before the diffusion pump kicks on. A really good mechanical pump can take the pressure down to < 5 microns.

Diffusion pump

A diffusion pump is normally not used in a demo fusor because it can take the pressures down a lot lower and there must be remaining air molecules to ionize. The animation below demonstrates the process of a diffusion pump.
http://www.edwardsvacuum.com/uploadedFiles/Resource/Corporate/About_Us/diffusion_pump.swf


The High voltage system

A very high voltage is needed to attract the air molecules to the grid, usually about -1,000 to -10,000 volts aka. -1kv to -10kv (kilo volt). The grid is at the center of the fusor and is wired to a negatively biased power source. We will get into more details later. 
 

The Chamber 

The vacuum chamber is a vary expensive part of the fusor unless you build your own ( go to http://rtftechnologies.org/physics/fusor-mark3-hemisphere.htm for more info), in which case it is still very expensive but not the same as a manufactured one. They are usually made of stainless steel 304 although some demo fusors can be made out of bell jars. They must be vacuum tight.
 


















-Not my fusor-

Designing a demo fusor

Welcome,
This section of my blog will introduce you to the demo fusor. A demo fusor is a device that looks as if its doing fusion but is actually ionizing the residual air molecules. 

As Richard Hull from fusor.net puts it, "The demo LOOKS and OPERATES just like a real fusor. With no deuterium, it can't do any fusion. What it does is that it takes residual air molecules remaining in the demo fusor, which never has a secondary pump, and ionizes the various atmospheric gases. These ions and electrons look like and act like a real fusor to the eye and it also operationally mimes how a real fusor needs to be run. 


Isn't the effect beautiful! 

 A real fusor requires a special gas called deuterium which, right now, is very hard to acquire.

 In the next few posts, you'll learn how to build a basic demo fusor and where to get thee parts. Good luck!