RogerBW's Blog

Several right-minded people went to Culham, on one of their rare open days, to visit the Joint European Torus and the Mega Ampere Spherical Tokamak (which should really be called a Sphekamak but never mind). (Images follow; all are cc-by-sa.)

These are both experimental machines, feeding data into the design and construction of ITER, which should finally produce more power from fusion than it takes to run it. Actual fusion power stations are being forecast for 2050 or later, rather than the conventional twenty-or-so years.

1/20 scale engineering model of the JET - design started in 1973, and computers of the day weren't good enough to verify that everything would fit together.

Really, how can one resist?

MAST building. It's all like this. Rain was clearly audible on the roof, far above.

MAST containment, about a metre of boronated concrete to catch stray neutrons.

Main vessel workshop and MAST cylinder.

The old central solenoid.

Vessel lid, in a positive-pressure tent.

Copper-plate ion trap. A charged particle beam is sent through a neutralising medium to turn it into a neutral particle beam, which goes into the chamber to add energy. Any charged particles remaining in the beam are pulled out with electrical fields and caught in the trap.

I think these are the ion separators.

Bottom plate (within the plastic sheeting). "Crown" open to accept new central solenoid.

More of the MAST chamber.

Padlocked breaker board.

We got rushed past this, but I think it's some sort of gas or water injection system.

Main solenoid contact, several pounds of copper.

Explanatory model. Main plasma-holding magnets (poloidal field) are the P series, with the toroidal field magnets further out and not shown; divertor magnets (catching cooled plasma, ideally after several tens of turns round the central solenoid) are the D series, and that seems to be where most of the engineering effort is going these days. The "nose" near Dp is an innovation to keep non-cooled plasma from getting pulled out; JET has a simple trough at the bottom (and top).

The bridge between buildings - with fan-heater for winter.

CESG doesn't give this advice any more. But it's a pretty old poster.

Access has been PURGED!

Interferometry laser for measuring plasma velocity.

Remote operations control room for JET, including MASCOT control rig at mid-right. (The T stands for "Transistorised". That's how old the core design is.)

One of the doors into the JET "hot cell".

The main door takes some fifteen minutes to open or shut. The section above it can be lifted too, when cranes need to be run through.

Personnel lock.

Beryllium handling facility. (They're using tungsten-beryllium tiles on the inner surface at the moment, rather than the older carbon fibre tiles. It's useful in terms of not contaminating the plasma, but non-fun to work.)

Training facility. One of the octants was heavily modified for experiments, and building a new one seemed like a better bet than putting it back into conventional service; so it's now one-eighth of the full-size mockup of the JET that's used for maintenance training and for running through particularly fiddly operations in advance.

The interior of the mockup.

Crane holding the MASCOT manipulator (which is moved into the mockup just as into the real thing).

Anonymous equipment racks.

Panorama of the inside of the JET.

Cutaway model.

Divertor coils.