What is a plasma? Plasma is an electrically conductive gas, composed of unbound ions and electrons. 99.9% of the visible matter in our universe is plasma and is found in stars, our sun, interstellar gas, and comet tails, to name a few. Plasmas are strongly influenced by electromagnetic fields and exhibit collective behavior as a result of particle-field interactions. Plasmas support a rich variety of wave phenomena and can form structures, such as filaments, tubes, and layers.

Plasma applications. Plasmas provide radiation and contain high energy particles that produce chemically reactive species. Applications that exploit these properties include thin-film deposition for semiconductor manufacturing, plasma lighting systems, and sterilization of medical devices. Other applications such as electric thrusters, plasma actuators, and fusion reactors take advantage of the conductive nature of plasmas and their response to electromagnetic fields. Electric thrusters propelled the Dawn spacecraft to Ceres and Vesta as shown in this image and are also currently being used on hundreds of satellites in Earth orbit.

Plasma-liquid & plasma-solid interactions. Plasmas contain reactive species that interact with surrounding material to provide unique reaction pathways. This enables modification of everything from semiconductors to living tissue, and forms the basis of plasma medicine, nanomaterials synthesis, and fabrication of microelectronics devices. The field of plasma-materials interactions provides extraordinary opportunities for cross-disciplinary collaboration, as it exists at the intersection of plasma physics, surface science, atomic and molecular physics, chemistry, and condensed matter physics.

Fusion energy. Fusion devices contain a hydrogen plasma under intense temperature and pressure, achieved either by magnetic or inertial confinement. The vessel walls are exposed to a harsh environment in which they are subject to high heat loads, neutron damage, chemical erosion, and physical sputtering by high-energy particles. The interaction between the edge plasma and the surrounding material profoundly influences the conditions in the core, making plasma-materials compatibility one of the main scientific challenges in achieving fusion energy. Check out this PhD Comics video on fusion featuring PPPL scientists!