Project Sherwood and magnetic fusion

In early 1952, Livermore’s soon-to-be first director Herbert York gave a series of lectures at the University of California, Berkeley on the physics issues of controlled thermonuclear reactions (CTR) and the country’s fusion programs at Princeton and Los Alamos. York’s lectures on magnetic fusion had the specific goal of stimulating the physicists in the audience to join him in forming a new laboratory focused on nuclear weapons development and fusion research. One physicist in attendance at York’s lectures was Richard Post. According to Post, who would become a leader and luminary in the field over the next six decades: “I was fascinated by the lectures. I wrote York a memo describing an idea I had…and he invited me to start a controlled fusion research group at Livermore when the Lab was founded...”

Livermore’s CTR Program, which was part of the Atomic Energy Commission’s “Project Sherwood,” began when the Laboratory opened in 1952. Over the first few years, the Livermore team explored many different devices and methods with researchers eventually settling on the magnetic mirror approach, in which hot fusion plasma would be confined in a cylindrical region by a uniform magnetic field with intensified fields at the ends.

Over CTR’s first six years of existence, fusion research under Project Sherwood had remained classified. However, according to Post, by the late 1950s “it was recognized that the problem [of achieving fusion] would be long and difficult and that all would benefit from a free flow of information.” In 1958, the weekend before the opening of the second United Nations International Conference on the Peaceful Uses of Atomic Energy (“Atoms for Peace”) in Geneva, the United States and Great Britain announced an end of secrecy in their CTR efforts. The Soviets subsequently proclaimed that they had built the world’s largest fusion research device, a doughnut-shaped machine called a tokamak, and declassified their research as well.

Livermore’s CTR team had been exploring two experimental lines using two series of machines – one effort led by Post and the other by Fred Coensgen. At the 1958 Atoms for Peace conference, Livermore’s achievements in magnetic fusion were announced and included the creation of a hot, mirror-confined plasma using the Toy Top device and the confinement of a hot-electron plasma between mirrors for a millisecond using the Table Top machine.

By the late 1970s, after overcoming a series of roadblocks in the formation and containment of plasmas, Livermore researchers were making enormous strides in both the quality of their insights and in the size of their experimental equipment. In 1977, the Energy Research and Development Administration (predecessor of DOE) approved $11 million for the Tandem Mirror Experiment (TMX), which promised significant performance improvements. That same year, construction also began on the Mirror Fusion Test Facility (MFTF), an advanced experimental fusion device designed to be an intermediate step between the existing mirror machines and an experimental fusion reactor.

Success with TMX experiments over the next several years led to a substantial modification of the original MFTF design into a large tandem mirror configuration called MFTF-B. The scope of the project was immense, with a 58-meter-long vacuum vessel and the largest set of superconducting magnets in the world. When the MFTF-B was finally completed in 1986, it had become the Lab’s largest construction project to date, at $372 million.

According to Keith Thomassen, who was the program manager for the MFTF, the energy crisis of the 1970s fueled “support for the development of alternative energy sources.” While MFTF was a “wonderful engineering feat,” the facility eventually fell victim to declining budgets and waning support for exploring energy alternatives. In 1986, shortly after the ceremonies at Livermore marking the completion of MFTF, the Department of Energy (DOE) mothballed the project. The machine was turned off before it was ever turned on.

While the decision was a major setback for fusion energy research at Livermore, scientists continued work on other approaches to magnetic fusion with collaborative studies of tokamak performance using the DIII-D tokamak at General Atomics and the NSTX-U spherical tokamak at Princeton Plasma Physics Laboratory.