Concept definition of vacuum system for loop operation of large helical device

Abstract

As the Large Helical Device (LHD), which is under construction at the National Institute for Fusion Science, is installed in a super conducting magnet as confinement magnetic field, it is capable of operating in a steady state loop operation, if proper particle controls of both upstream (plasma region) and downstream (exhaust, impurity removal, H-isotope separation and refueling) are achieved. In the following, not only is the concept of the steady state loop operation described but also several hardware developments to meet this requirement are discussed.