Princeton Plasma Physics Laboratory

Princeton is home to the Princeton Plasma Physics Laboratory (PPPL), a Department of Energy (DOE) National Laboratory that is managed by Princeton University. PPPL, with about  450 employees, is dedicated to developing the scientific and technological knowledge base for fusion energy as a safe, economical, and environmentally attractive energy source for the world’s long-term energy requirements.  The Laboratory also examines the basic science and other applications of plasma physics and conducts a variety of popular educational programs for the New Jersey community.


Fusion is the power source of the sun and stars.  It is the fusing of two positively charged atomic nuclei.  This reaction converts mass to energy, which appears as heat that can be utilized for either electric power production or as process heat for industry or water desalination.

Magnetic fusion energy is created in laboratories by heating a gaseous fuel made up of isotopes of hydrogen (deuterium – which is extracted from water – and tritium – which is easily bred within the reactor) to temperatures of approximately 100 million degrees Celsius – more than six times hotter than the sun – in specially designed machines surrounded by magnets to confine the hot plasma.

Benefits of Fusion Energy

  • The major fuel used to create fusion energy – deuterium – can be readily extracted from ordinary water.  Thus, fusion is capable of providing a large-scale energy supply to all nations using domestically available, virtually unlimited fuel;

  • Since no fossil fuels are used, there are no greenhouse gas emissions;

  • Fusion is inherently safe, with no possibility of a meltdown or a large uncontrolled release of energy;

  • There is no need for long-term waste disposal, since fusion does not form any fission products.

Remaining Challenges in Fusion Energy

Fusion energy has been – and is – created routinely in laboratories in the U.S. and around the world.  However, at this point, we can only sustain that energy for milliseconds at a time.  The challenge is to advance the physics, materials, and technology to the point that we can maintain that energy for longer periods of time; to produce more energy from the reaction than was necessary to create the reaction; and to create a self-heating “burning plasma,” which is a major next step for fusion.

U.S. Fusion Program

The DOE Office of Science’s Fusion Energy Sciences (FES) program provides the scientific foundation for fusion energy. Clean, safe and plentiful, fusion energy is critical to the nation’s future energy security.  In partnership with the U.S. fusion community, our office advocates for:

  • National User Facilities: DIII-D at General Atomics (GA) in California and NSTX-U at the Princeton Plasma Physics Laboratory (PPPL) offer capabilities to advance critical scientific and engineering innovations in the magnetic confinement of fusion-relevant plasmas. These world-class facilities include cutting-edge diagnostic instrumentation and outstanding research staffs.  Combined, these facilities serve nearly 1,000 users.
  • University Programs: University-led research plays an indispensable role in the U.S. fusion program. Universities are an essential incubator of ground-breaking scientific ideas and discoveries and a source of expertise and ideas for research conducted on major experimental fusion facilities in the U.S. and worldwide.  They also play a critical role in training the next generation of U.S. plasma and fusion scientists
  • National Labs/Private Industry: Along with universities, national labs and private industry provide critical experimental, theoretical, and computational expertise and access to resources for the U.S. program in areas such as advanced fusion concepts, materials development, fusion theory and computation, advanced instrumentation, and high energy density laboratory plasmas.
  • U.S. Partnership in the ITER Project: ITER is the largest international science collaboration in the world and will demonstrate the scientific and technological feasibility of producing fusion power, an essential precursor to ultimate commercialization.  The U.S., along with six international partners, is designing and domestically manufacturing components for the project, which in December 2017 passed the 50% complete mark for First Plasma. Despite bearing only 9% percent of construction costs, the U.S. will have access to 100% of ITER–developed technology and scientific data.  Over 80% of U.S. ITER funds are spent in the U.S.
  • International Collaborations: U.S. researchers leverage fusion efforts worldwide to advance key elements of fusion science and technology. This research includes substantial collaborations on the EAST facility in China and the Wendelstein 7-X stellarator in Germany, as well as efforts in England, South Korea, and Japan.

Together, these elements provide the scientific basis for fusion energy, the foundation for the innovative next steps in the U.S. fusion program, advances in plasma science, and valuable research and training opportunities for the next generation of scientists and engineers.