The technology already exists to build a control system but, with the large number of interfaces involved and the exacting demands of such high-speed real-time control, major effort is required in design and software configuration.
The system is likely to have a hierarchical architecture, with a Supervisory Control and Data Acquisition (SCADA) system, processing operator commands and displaying information received from the following sources:
- Common clock and timing system
- High speed data acquisition system
- 100 x Laser control systems (each laser comprising 10 beamlets)
- 1000 x 'Beamlet' control systems (each amounting to one tenth of a HiPER Laser)
- Target Injection system
- Target tracking system
- Target engagement system
- Reactor control system
- Building controls
- Safety system
A plant start command will initiate the laser control systems, performing an automated alignment sequence before firing the lasers. The lasers will warm up and automated alignment will adjust for temperature differences within the laser chain.
When not operating, the reactor will be held at vacuum with the lithium coolant circulated through a pumping arrangement with a restrictor, to maintain temperature and prevent the coolant from solidifying in the lithium breeder blanket. This is a similar arrangement to the system used in fission reactors cooled by liquid sodium.
When the lasers are warmed up, the injector control system will command the injection of a fuel pellet. Once fired into the reactor, the pellet will be tracked in flight by the target tracking system. Information on its position and estimated point of closest travel to reactor centre are passed to the target engagement system which calculates the corrections required for position and time of arrival of the laser output pulses, triggering the lasers with the precise timing required.
When fusion events in the chamber have brought the reactor up to operating temperature, primary coolant is diverted through a heat exchanger by the reactor control system. This heats a secondary coolant medium which drives turbines and generates electricity.
Information from each fusion event is captured by the high speed data acquisition system for analysis by the SCADA system. Longer term corrections are fed back to fine tune the process.
During operation and when the facility is in maintenance mode, the building control system maintains the building in a suitable state, including control of air temperatures, access and egress, distribution systems and services.
The safety system will be stand-alone, capable of shutting down all facility operations or, (in the event of a fault) even a single laser. The system will monitor other safety sub-systems for each of the lasers, the reactor and the injection system. The safety system is likely to comprise a mix of hard wired logic and safety certified programmable devices.
