ENGINEERINGNET.EU -- In late February China completed and shipped its first major component for the project - 660 metres of toroidal field dummy conductor; while in Italy in early march the Italian Consortium for Applied Superconductivity (ICAS) completed the commissioning of the jacketing line facility, as well as equipment needed for the manufacturing of conductors.
The superconducting magnets are some of the highest value and most essential components of the Iter reactor, which is soon to start construction at Cadarache in Southern France.
The reactor is to be a kind of tokamak – a doughnut-shaped vacuum vessel which, when operational, will confine and heat a plasma of deuterium and tritium ions to achieve sustained nuclear fusion.
Confinement of the plasma is maintained through the toroidal field system which keeps the plasma moving around the chamber, and a poloidal field which pinches the plasma and keeps it away from the walls. In total Iter will require 16 toroidal field and six poloidal field coils.
Each D-shaped toroidal coil contains multiple strands of superconducting cable, and weighs in at about 363 tonnes. Each cable consists of about 1000 strands of a special alloy of niobium and twisted together and encased in a steel jacket.
The 'dummy' version replaces this alloy with copper so as to qualify the cabling and jacketing process without wasting the more valuable superconducting material.
In the jacketing process long sections are welded together into a line about 750 metres long and the cable is drawn through it, allowing weld quality to be checked and repaired if necessary.
The schedule for the Iter project looks set to be delayed by a year, in part due to the disruptive influence of the natural disasters that struck Japan last March.
(source & picture: World Nuclear News)
