Plasma Physics and Nuclear Fusion J. C. Sprott Department of Physics University of Wisconsin - Madison Presented to Physics 208 on October 30, 1998

Outline n Fission versus Fusion n Requirements for Fusion n Plasma Characteristics n Plasma Confinement n Experimental Devices

Advantages of Fusion n Inexhaustible Supply of Fuel n Relatively Safe and Clean n Possibility of Direct Conversion

Requirements for Fusion n High Temperatures n Adequate Densities n Adequate Confinement Lawson Criterion: n  > s/m 3

Two Approaches n Inertial Confinement: u n  / m 3    s n Magnetic Confinement: u n  / m 3    1 s

Magnetic Confinement n Magnetic Field Limit: B < 5 T n Pressure Balance: nkT  0.1B 2 /2  0 n ==> n  / m T = 10 8 K n Atmospheric density is 2 x / m 3 n Good vacuum is required n Pressure: nkT  1 atmosphere Confinement:   1 s n A 10 keV electron travels 30,000 miles in 1 s