Page 371 - Fundamentals of Magnetic Thermonuclear Reactor Design

348 Fundamentals of Magnetic Thermonuclear Reactor Design

FIGURE 11.18 Extra protective make switch.

only be maintained by the water flow for fractions of a second, a separator with
a separate explosive charge is placed in series with the commutation unit. The
explosives in the separator and commutation unit are ignited simultaneously.
Pressure produced by the explosion sets the dielectric cylinder in motion. It
disrupts the membrane and, once sited down, separates the central current lead
from the upper one, thus providing the electric strength of the whole device after
circuit opening.
The EPMS is part of the SNU. Its role is to protect multiple-acting switch-
ing equipment in the event of an FMS failure. It has a simple design making it
reliable and efficient (Fig. 11.18).
The EPMS contact system includes two stationary coaxial cylinders, whose
inner butt ends have conical recesses with radial triangular projections. The re-
cesses house an explosive charge, a polyethylene (PE) ring and an aluminium
ring. A multilayer PE film is used as an insulation between the stationary contacts.
The film thickness determines the pressure that the contactor can withstand when
open. The pressure of detonation products is transmitted through the PE ring to
the inside of the contact ring. This causes the ring to extend into the teeth of the
stationary contacts, thus cutting the PE film. The response time is about 20 µs.
The advantages of the described switching devices are their reliability and
high durability. Similar technical solutions may be employed in PS systems for
next-generation stationary tokamak reactors.

REFERENCES
[1] F.M. Spevakova, A.M. Stolov, (Tokamak
power supply systems), (Tokamak Engineer-
ing Problems), Energoatomizdat, Moscow, (1986) 9–68 (in Russian).
[2] N.A. Daniel, B.A. Larionov, N.A. Monoszon, et al. EMS power supply system, Plasma
Devices Oper. 1 (1992) 253–266.
[3] I. Song, A. Roshal, V. Tanchuk, et al. The fast discharge system of ITER superconducting
magnets, in: Proceedings of the International Conference on Electrical Machines and Systems,
ICEMS, Beijing, China (2011).