Project Matterhorn was the code name for controlled thermonuclear research started by Lyman Spitzer at Princeton University during the Cold War. In 1951, Spitzer outlined the basic concept for creating a stellarator, a device for confining and heating ionized hydrogen gas to release fusion energy for the production of power. In 1951 Project Matterhorn was created, supported by The US Atomic Energy Commission and Princeton University. Spitzer's fusion research was housed on Princeton's Forrestal Campus where Princeton physicist John Wheeler conducted nuclear weapons research. Spitzer's research was code-named "Matterhorn S" and Wheeler's "Matterhorn B." Project Matterhorn did crucial research which contributed to the creation of the Hydrogen Bomb. When the nuclear weapons research ended in 1958 the project was declassified and in 1961 became the Princeton Plasma Physics Laboratory, which is still in operation today.