The ITER toroidal field model coil project

208 A. Ulbricht et al. / Fusion Engineering and Design 73 (2005) 189–327
Table 4.3
The test procedure for Phase 2 (TFMC + LCT coil)
Position number Procedure
1 Checkouts at RT
2 Cool down
3 Checkouts at operation temperature (∼4.5 K)
4 Single coil test TFMC analog to [20], no cycling
5 Single coil test LCT coil up to 11.3 kA at 4.5 K analog [20], no cycling, no current sharing measurements
6 TFMC + LCT coil, low current checkouts (IT = 3.5 kA, IL = 0.8 kA, F = 0.0025 × F0 a ) at 4.5 K
Ramp up–hold–ramp down (ramp rate TFMC: 22 A/s, LCT: 5 A/s)
Ramp up–hold–inverter mode discharge (max. power supply voltage) (ramp rate TFMC: 79 A/s, LCT: 18 A/s)
Ramp up–hold–safety discharge (exponential current decay) (ramp rate TFMC: 22 A/s, LCT: 5 A/s)
7 TFMC + LCT coil, ramping up in selected currents steps in fractions of F0 at 4.5 K
{IT [kA], IL [kA], F/F0 [1]}: {10, 2.3, 0.021}, {20, 4.6, 0.082}, {30, 6.9, 0.18}, {35, 8, 0.25}, {49.5, 11.3, 0.5}
For each step: repeat procedure of position 6b 8 LCT single coil test up to 16 kA at 3.5 K analog to [20], no cycling, no current sharing measurements
9 TFMC at 4.5 K + LCT coil at 3.5 K, ramping up in selected currents steps in fractions of F0
{IT [kA], IL [kA], F/F0 [1]}: {60.6, 13.9, 0.75}, {66.4, 15.2, 0.9}, {70, 16, 1.0}
For each step: repeat procedure of position 6b 10 TFMC at 4.5 K + LCT coil at 3.5 K, optimisation of the heating procedure without current
11 TFMC at 4.5 K + LCT coil at 3.5 K, determination of the operation limits (TCS) by stepwise increase of the heating
power of inlet helium of two pancakes at F0
{IT [kA], IL [kA], F/F0 [1]}: {70, 16, 1.0} till trans. into normal conducting state occurs
12 TFMC at 4.5 K + LCT coil at 3.5 K, TFMC cycling by a total of 28 triangular current pulses at four current levels
with a ramp rate 140 A/s and LCT coil at 16 kA steady state operation
{IT [kA], IL [kA], F/F0 [1]}: {35, 16, 0.5}, {52, 16, 0.75}, {63, 16, 0.90} c , {70, 16, 1.0} c
13 Repeat Pos. 9 for {70, 16, 1.0}: ramp up–hold–ramp down, check mechanics
14 Repeat Pos. 10 + 11 for {80, 14, 1.0}
15 Repeat Pos. 10 + 11 for {80, 16, 1.14}
16 TFMC fast high voltage discharge d : IT = 6 kA, UT = 4.8 kV, τ = 26.5 ms
17 Standardised 25 kA safety discharge for measurement of electrical losses performed at suitable positions in the test
procedure
18 High voltage (HV) tests: DC, AC, partial discharge, pulse voltage
These tests are performed in the relevant position numbers of the test procedure, e.g., 1, 3, 15–17
19 Daily tests before starting testing: DC HV test, low current safety discharge
20 Final checkout at operation temperature
21 Warm up
22 Checkout at room temperature
a Rated attractive Lorentz forces F0 ∼ IT × IL; IT = ITFMC; IL = ILCT; F0 is defined for the reference load case TFMC 70 kA/LCT 16 kA.
b The inverter mode discharge was omitted for IT > 35 kA because the faster achieved IT ∼ 0 led to undefined power supply operation, which
caused excessive electric losses in the TFMC. The reason is the magnetic coupling between TFMC and LCT coil, which has for same inverter
voltage a smaller ramp rate caused by much higher inductance (LLCT = 1.57 H, LTFMC = 0.027 H).
c During cycling at these current levels two quenches of the LCT coil occurred. The reason was a too low temperature margin. After lowering
the inlet temperature to 3.0 K no more quenches occurred.
d The LCT coil is shorted by its safety discharge resistor.
the operation of the LCT coil winding in the temperature
range between 3 and 3.5 K. This was necessary
to operate the NbTi coil up to a current of 16 kA. For
the cool down, the He was supplied directly from the
2 kW refrigerator to the test configuration in a separate
transfer line, whereas during operation at the temperature
level of 4.5 K, the 2 kW refrigerator liquefied He
into the control dewar (B250), while both coils and