Alternating Current Tokamak Reactor with Long Pulses

Abstract

Alternating current (ac) tokamak operation in the reactor parameter range is studied by considering the volt-second consumption, A simple condition for obtaining ac operation with nearly constant pulse length is given by Lp/Rp < Td, ss (Lp is the plasma inductance, Rp is the plasma resistance, and Td, ss is the discharge length in the standard operation), assuming time-independent plasma parameters. The discharge length for ac operation is shorter than for standard operation and is given by Td, ac = Td, ss (ϕt – 2ϕL)/(ϕt – ϕL) where ϕt is the total transformer flux and ϕL is the plasma inductive flux. Alternating current operation is found to be advantageous in a large reactor having a large ohmic transformer flux ϕL satisfying . The superconducting magnetic energy storage system is proposed as an attractive power supply for ac operation in a large reactor.