Stability issues of the ITER divertor experiment and laboratory (IDEAL) conceptual design study

Issues dealing with the plasma stability of the IDEAL conceptual design are presented. Of basic concern is stability of the plasma with respect to the interchange mode and the creation of a stable average minimum-B configuration. Interchange stability is achieved by the addition of a quadrupole magnetic field at each end of the device. The shaping function of the quadrupoles was found to be more than adequate for interchange stability. Numerous construction issues impacted the design of the quadrupole magnets and their effect on stability is assessed. One option for IDEAL is to drive an axial current down the device as an auxiliary source of plasma heating. Axial current alters the stability properties of the device introducing the possibility of kink modes which may limit the overall power achievable by this method.