The effect of plasmas had been noticed as early as 1901, when Marconi found that radio waves could cross the Atlantic in spite of the curvature of the earth. We now know that the waves were reflected by the ionosphere. The study of plasmas probably began with Irving Langmuir’s experiments on sheaths in 1928, and it was he who coined the name plasma in a blood-free context. Practical use of plasmas began in the late 1940s with E.O. Lawrence’s invention of the calutron (named for the University of California) for the separation of U235 from U238 for use in atomic bombs. It was the effort to tame the H-bomb into a steady source of electricity—hydrogen fusion—that spawned modern plasma physics. More on that later.