A Visit to General Atomics DIII-D Tokamak Fusion Facility
by Bill Cress
Last Friday while in Los Angeles I was very fortunate to have scheduled a pre-arranged private tour of General Atomic’s DIII-k Tokamak Fusion Facility in San Diego California. I was met by Richard Lee senior Scientist in overall charge of the Fusion Energy Education Group. He was kind enough to go above and beyond and insure that I had a complete understanding of their facility in the 2 hours we spent together. The General Atomics Tokamak is currently the 3rd largest in the world with an even larger one, ITER under construction in France. Built in 1976 and replaced with an upgraded version in 1986, this is a magnanimous device! Constructed primarily of high grade Stainless Steel and Aluminum. There are huge copper coils that circumscribe the machine, placed every several feet around the chamber. Additionally smaller copper coils are placed around the chamber perpendicular to the main copper coils and there are also diagonal coils as well. all electrically charged and used to guide and direct the reaction when the Tokamak is ignited. It uses Deuterium and Tritium as fuels for the machine, however because of the dangers of Tritium, and the lack of ability to handle tritium, they are only using Deuterium. Tritium is not needed for most plasma experiments. The facility is completely funded by The Department of Energy.
It is housed in a building of approximately 100,000sf with a sliding concrete slab that is put in place over the Tokamak when it is ignited, this controls any errant neutrons that may escape through the roof and contaminate neighbors ( done to satisfy environmentalist!) This Tokamak is the 2nd largest user of electrical power in the state of California. It is powered by 175,000 megawatts of electricity. The devise is fired only during 17 weeks of the year and fusion is only created for a 5 second interval at that time. Each shot costs several million dollars. The device is completely lined on it’s interior with approximately 2 1/2″ thick graphite tiles to keep the reaction from burning through the walls of the Tokamak. Reaching interior temperatures of 15 million degrees it’s easy to do. While I was there they were replacing some interior tiles and welding some interior seems that had deteriorated. 200 scientists are there and involved on a daily basis and more when it is fired. One picture shows the overall control room. I was surprised that they permitted me to take any pictures at all! Certain areas like the laser labs and microwave labs were off limits to pictures. Very serious stuff!. There are hundreds of thousands of connections and wires feeding the Tokamak, it’s amazing that anyone is able to know where anything goes! Richard did admit that sometimes they just run new lines rather than try to figure it all out! Richard introduced me to all of the staff along the way and it is a very interesting group of people. One in particular Charles Moeller who is one of the worlds leading experts on Microwave apparatus and launchers that survive in a fusion environment. He is the go-to guy and I have design on trying to attract him to Project Icarus as I believe he would be a great consultant and contribute significantly! This is a not to be missed tour if you happen to be in San Diego.