Possible control scenario of radial electric field by loss cone particle injection into a helical device

The possibility of controlling the radial electric field of toroidal plasmas by injecting high energy electrons along the reversible loss cone orbit of helical magnetic traps is investigated. It is well known that the radial electric field plays an important role in the confinement improvement scenario, especially in the low collisional regime in the physics picture of neoclassical theory. For this purpose, it is made clear that the most suitable particles are transit particles, which show a transition from helically trapped orbits to blocked ones. It is also found that a parallel AC electric field launched from outside assists this transition and makes it possible for particles to penetrate deeply into the plasma. In addition it is confirmed that the viscosity of the plasma coupled with the helical field configuration provides a bifurcation of plasma states and its stable solution results in an improvement of confinement.