ETC-Rel code: orbit trace code of relativistic electrons in a tokamak

A code ETC-Rel has been developed which traces the orbits of relativistic electrons in a tokamak. The canonical Hamiltonian form for the relativistic guiding center drift motion of an electron has been newly derived for the development of the code. The equations of motion for the guiding center are described using Boozer coordinates. Therefore, a mapping routine has also been developed to visualize the orbits in real space (Cartesian coordinates). Simulations performed using the ETC-Rel code have demonstrated that the magnetic perturbations at disruption cause a collisionless loss of runaway electrons. These predictions agree closely with recent JT-60U experiments on fast plasma shutdown, showing that it is possible to prevent the generation of runaway electrons. (author)