JET Visit

August 5, 2017 at 8:58 pm

JET – Joint European Torus operates out of the Culham Centre for Fusion Energy, CCFE in the U.K.  It’s between Cambridge and London. Mega Ampere Spherical Tokamak, MAST, also operates out of CCFE.  It’s a huge campus and JET is the largest fusion experiment in the world.  Excluding perhaps the Wendelstein Stellerator and not counting ITER that is…

Partial view of the JET's core. Actual core is only about 3 cubic metres, but equipment surrounds it.

Partial view of the JET’s core. Actual core is only about 3 cubic metres, but equipment surrounds it.

JET consumes so much power that they have to call up the power people and check if it’s ok to turn on.  Turn ons are prohibited around 5PM on Winter evenings because there are too many people are coming home from work and turning on the heat. They have two 750 ton flywheels to store power.  In a flywheel, energy is stored in a rotating object, which can be charged up (sped up) and then released later.  These flywheels ensure JET doesn’t draw too much electrical power at once from the grid, instead charging up the flywheels over time, which then provide the massive pulses of power required – along with power draw from the grid.  The power requirements for fusion at this scale are ginormous.  Also, the coils in the JET reactor are water-cooled copper, as opposed to superconducting, they’ve never been upgraded – superconducting coils would lend a noticeable increase to performance.

I was invited for a tour after a talk I gave a year or two ago, and visited with my family in January of this year. It was a fantastic experience to see the scale of work done, and the resources available. I even spotted a shiny Leybold backing pump in one side room, would have liked to bring it home.  Fusion research has driven innovation in a number of areas related to operating the reactor.  Something I found particularly interesting was the remote handling apparatus developed.  The inside of the reactor can be worked on with no direct human contact, check it out!  Video shows real setup at 3:40, I was told that the best remote handling operators are video gamers.

 

A complete scale model of JET reactor! From the pre-CAD days.

A complete scale model of JET reactor! From the pre-CAD days.

Demo fusor at JET

Demo fusor at JET

 

They have a nice demo Fusor in CCFE. People get time and money allowances for relevant side projects, and one was a portable fusion device to cart around and raise awareness of fusion. The device is demo because it has a pretty much the same visual effect for their purposes, no need to actually fuse! Their biggest problem was vacuum leaks, no surprises there huh. It uses a dry scroll pump rather than a rotary vane.  A demo fusor is better described as a half fusor, the name is misleading.  In a normal fusor, a deuterium plasma creates the purple glow, you can get a similar purple glow with much less trouble in a demo fusor – though no fusion.  Instead of deuterium, it’s just air that creates the glow, and the voltage doesn’t need to be as high to ignite a plasma, so technical requirements are much reduced.

The people there were extremely kind and helpful. I didn’t see any experiment in progress, but to see all the equipment was a fantastic experience.  Many thanks to Pauline, Andrew, Chris and Nick.  On a smaller scale, the Fusor here is close to completion.  At the minute I’m setting up the myRIO and LabView control software, and connecting stepper motors to each of the valve’s shafts.  What’s left is to order deuterium, get the high voltage supply sorted, wait for the turbopump to be returned from servicing (thanks to ProVac and Leybold for sorting that!) and then I’m pretty much ready to go.  Yeehaw.

 

View inside the JET hangar, you're surrounded by equipment on all sides.

View inside the JET hangar, you’re surrounded by equipment on all sides.

Second, dummy reactor copy for trying out all modifications of fusion core before proper implementation.

Second, dummy reactor copy for trying out all modifications of fusion core before proper implementation.