Patent Number: 042773067
Section: claims

1. In a toroidal plasma confinement method including the steps of providing a toroidal vacuum chamber zone, providing a high temperature hydrogen plasma in the vacuum chamber zone and a toroidal magnetic field in which the plasma is embedded, and providing a poloidal magnetic field in which the plasma is embedded, the improvement comprising controlling plasma impurities by generating a magnetic plasma confining field for confining a high temperature plasma having continuous inner flux lines in a high temperature plasma zone in a plasma vacuum chamber without internal divertor coils, which chamber is elongated in a direction along the major toroidal axis, generating a region of lower magnetic field strength in said elongated vacuum chamber for confining a plasma of lower temperature than said high temperature plasma to provide said poloidal field with a field configuration in which the radially outer flux lines of said poloidal magnetic field about the high temperature plasma are axisymmetrically bound to terminate at the vacuum chamber wall about said region of lower magnetic field strength adjacent the high temperature plasma in a direction along the major toroidal axis opposite the direction of positive ion toroidal drift, providing a source of pure hydrogen at the high temperature plasma zone, evacuating the low temperature plasma zone, and maintaining a low temperature plasma adjacent the high temperature plasma. 2. A method in accordance with claim 1 wherein said low temperature plasma in maintained by r-f heating. 3. A method in accordance with claim 1 wherein impurity control is accomplished at least in part by collisions between protons and impurity ions sufficient to produce collisional pumping. 4. A method in accordance with claim 1 wherein said impurity control is accomplished at least in part by electrostatic pumping.