THE PRESENT STATUS ANDPROGRESS OF EAST(HT-7U)

TOKAMAKEAST(HT-7U) Team Presented by Weng Peide

Institute of Plasma Physics, Chinese Academy of Sciences, P.O. Box 1126, Hefei, Anhui, 230031, P.R. China

October 2003

ASIPP

Mission of the EASTThe main mission of the project is to develop anadvanced full superconducting tokamak and explore thescience and technological bases for fusion reactor.

• Demonstrate of steady-state operation with highplasma performance.

• Investigate of advanced tokamak physics anddemonstration of stationary H-mode operation bystrong shaping, current profile control and auxiliary heating.

• Investigate of particle and heat fluxes handling on atime scale much longer than the wall equilibration time.

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Major Radius Ro 1.75 m

Minor Radius a 0.4 m

Toroidal Field Bo 3.5 T

Plasma Current IP 1 MAElongation Kx 1.6 - 2

Triangularity d x 0.4-0.8Pulse length 1000 sHeating and Driving:( first phase)

ICRF 3 MW CW

LHCD 3.5 MW CW

ECRH 0.5 MW

Configuration:Single null divertorDouble-null divertorPump limiter

Conductor design and R&D Conductor development• NbTi cable in conduit conductor• Lowest cost: using existing strands• Using segregated copper to increase copper ratio (as

stabilizer)• Different surface coating to control AC losses• Lower operating temperature to increase margin

Several versions of the conductor have been developedand tested in ASIPP, ISSSP Kurchatov and Sultanfacility at CRPP.

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Sub-cable test at ASIPP

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CICC for EAST TF & PF magnets

Large proportion of segregatedcooper in conductor (68%)Different surface coating forTF and PF respectively

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Short Sample test

Four 15 kA TFand PF short sampleconductors with differentcoating on the strands andSS foil wrapping on thethird sub-cable have beenmade in ASIPP and testedin SULTAN facility atCRPP.The Ic, Tcs, AC lossesand stability againstmagnet field disturbanceof the samples have beenmeasured and compared

Results of AC loses measurement

Transient stability against Magnet field disturbance

0 2 4 6

0

2

4

6

8

10

12

14 PF3 PF3 PF2 PF2 TF TF PF1 PF1

f, HZ

ac lo

sses

, mJ/

cc

0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70

0

50

100

150

200

250

T*T/

s

Iop/Ic

TF 5.8T T=4.6K PF1 4.5T T=5.8K PF2 4.5T T=4.6K PF3 4.5T T=4.6K

5.0 5.2 5.4 5.6 5.8 6.0 6.2 6.4 6.6 6.8 7.0 7.2 7.4 7.6 7.80

5

10

15

20

25

30

35

40

45

50

55

60

65

B=4.5 Tdm/dt=2.8 g/s

TF PF1 PF2 PF3 calculated

Crit

ical

cur

rent

Ic (k

A)

Temperature T (K)

IC measurement

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0-20

0

20

40

60

80

100

120

140

160

TF: 4.5T,14.3kAPF1: 4.0T,14.5kAPF2: 4.5T,14.5kA

TF PF2 PF3

Inte

grat

ion

of (d

B/dt

)*(d

B/dt

)*dt

, T2/

S

Tcs-Top ( K)

0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.00.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

PF1&PF2: Void=36.67%PF3: Void=38.44%TF: Void=37.32%

(1/Void)0.72(19.5/(4*MF/(Visc*U))0.843+0.0265)*MF2*L/(2Dh*Dens*AHe2)

4 bar, 4 K Helium

PF2#PF1# TF

PF3#

∆P (1

00m

) [

bar ]

Mass flow [ g/s ]

Pressure VS mass flow rate

Test results• The Critical currents of the four conductors are lower than

the strand data 10-12% and the current sharing temperaturesof PF1 and TF are lower than the calculated value 0.2 K.

• The AC losses of four conductors are much lower thanexpected and have a non-linear behavior. The inclusion ofsegregated pure copper strands in the conductor will decreasethe coupling loss and consequently increase the transverseresistance greatly.

• The solder coating results lower inter-strand resistance canensure adequate current sharing, however, it bring highcoupling loss too, we will use it for TF magnet.

• The Nickel coating has relative higher inter-strand resistanceand can reduce the coupling loss effectively shows hightransient stability against magnet field disturbance, we chooseit for CS magnet.

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TF & PF conductor parameters ASIPP

CICC jacketing line

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PF coil

PF coil

PF coil

CS coil

TF coil supportsTF coil

EAST magnets

TF Magnet Design• The TF Magnet System consists of a toroidal

array of 16 D shape coils, each coil is composedof two packs of winding which to be wounduninterruptedly.

• NbTi Cable in Conduit Conductor withsegregated copper is chosen for TF magnet.

• The inner leg of TF coil cases is designed to bewedge-shaped to form a vault withstanding themagnetic centripetal forces.

• Vacuum pressure impregnation will be adoptedto enhance the insulation and integrity aftersetting coil into case.

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TF ParametersMaximal field at coil 5.8TTotal turns 16 × 130Coil size (D Shape) 3.52 × 2.51 mWinding type 6 pancakesConductor size 20.4 ×20.4 mmLength of each coil 2 × 593.5 mLength of cooling channel 201 mOperating current 14.3 kAOperating temperature 3.8 KTotal storage energy 298.5 MJ

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Stress analysis of TF magnet

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PF Magnet design

• The PF magnet system consists of three pair ofCentral Solenoid coils and four pair of Poloidalcoils. They are placed symmetrically about thedevice horizontal mid-plane.

• The flux swing of the PF magnet will be 10 VSand it could induce 1 MA plasma current andsustain it up to 10 seconds without auxiliarycurrent drive.

• NbTi Cable in Conduit Conductor withsegregated copper is chosen for PF magnet.

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18.6×18.620.8×20.8Conductor mm

PF13-14PF 11-12PF 9-10PF 7- 8PF1- 6

10Total flux swing VS

3.8Operating temperature K

6.8 /0.7dB/dt max T/s

14.5I max kA

1.54.3B max T

326020444140Turn

179221289103476Height mm

64685779188918891085Inner diameter mm

66506054267024011418Out diameter mm

PF Parameters ASIPP

I (kA)

t (s)

Current of PF coils

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Ip

TF coil case machining

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TF prototype coil winding

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PF coil winding

Vacuum pressure impregnation

equipment (VPI)for TF and PF coils

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TF coil after VPI

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Superconducting magnet test facility

Diameter available 3.1 m

Height available 4.7 m

Vacuum 1 × 10-5 τ

Maximal current 30 kA

Refrigerator 500W/4.5 k

The prototype of CS coil,two TF magnet and PFmodel coil have beentested in the facility

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CS model coil test

PF model coil test

0 100 200 300 400 5000

2

4

6

8

10

12

14

climb rate 300kA/sdrop rate 300kA/s

I

Cur

rent

(KA)

time(S)

0

5

10

15

20

25

30

35

40

mag

netic

fiel

d(kG

)

B1

CS prototype coil in the test facility

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2003-05-08 2003-05-09 2003-05-11 2003-05-13

0

50

100

150

200

250

300

Tin Tout

tem

pera

ture

of S

C co

il(K)

date

CS Coil cooling down

CS prototype coil test Simulate Plasma initiation

• excite the coil with the rate of 1 kA/s up to 15.2 kAand keep the flat top for 20 seconds.

• discharge the coil with dump rate –20 kA/s for 160ms up to 12kA, discharge the current from 12 kAto 10.6 kA with dump rate –10 kA/s for 140ms,from 10.6 kA to 6.6 kA with dump rate -5 kA/s for0.8 seconds, and -1.5 kA/s to 0.after that ramp the current from 0 to –13.2 kAwith the ramp rate -1.5 kA/s, keep the flat top for10 seconds and dump the current up to 0 with rateof 3KA/s again.

-10 0 10 20 30 40 50 60 70 80

-15000

-10000

-5000

0

5000

10000

15000

20000

ramp rate 3kA/s

ramp rate 1.5kA/s

drop rate 5 kA/s,0.8S

drop rate 1.5 kA/s

drop rate 10 kA/s,0.14S

drop rate 20 kA/s, 0.16 S(4.4T/s,0.16 S,0.7 T)

ramp rate 1kA/s(0.22T/s)

I=13.2 kA

I=15.2 kA(B=3.34 T)

Cur

rent

(A)

Time (S)

Current dm/dt 2.2g/s per channelTin=4.7K

Coil discharge simulate plasma initiation

14:15:3614:15:4414:15:5214:16:0014:16:0814:16:1614:16:2414:16:3214:16:40

-15000

-10000

-5000

0

5000

10000

15000

20000

T4

T3

T2b

T5

T2b: inlet temperatureT3, T4, T5: outlet temperature

tem

pera

ture

(K)

currentcu

rren

t(A)

Time

0 10 20 30 40 50 60 70

4.5

4.6

4.7

4.8

4.9

5.0

5.1

5.2

5.3

5.4

5.5

5.6

5.7

Time (S)

Outlet temperature rise due to coil fast discharge∆T max <0.5 K

CS prototype coil testAC losses test and Iq test

• Rise the current to 7.5 kA (∆B=1.65 T) withramp rate 5kA/S dB/dt=1.1 T/S) and drop thecurrent with same rate to 0.3 kA repeat 13times, measure the temperature rise . The outlettemperature T3,T4 and T5 increased 0.52-0.56K.

• Rise the current to 14kA with 1kA/s up and risethe current with 0.5kA/s continuously, the coilquenched when the current reach 16.37 kA.

15:58:24 15:58:36 15:58:48 15:59:00 15:59:12 15:59:24 15:59:36 15:59:48-1000

0

1000

2000

3000

4000

5000

6000

7000

8000

currentCu

rren

t(A)

0 10 20 30 40 50 60 70 80 90 100

5.0

5.5

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

dI/dt=5 kA/sdB/dt(max)=1.1 T/sdelta T (max)=1.6T

T3

T4

T5

T2b

T2b: Inlet temperatureT3, T4, T5: outlet temperature

tem

pera

ture

(K)

AC losses test

10:3610:40

10:4410:48

10:5210:56

11:0011:04

11:0811:12

11:1611:20

11:2411:28

11:3211:36

11:4011:44

11:4811:52

11:5612:00

-2000

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

T3T4T5

T2b

Tem

pera

ture

(K)

currentC

urre

nt(A

)

Time

0 10 20 30 40 50 60 70 80

4

6

8

10

12

14

16

18

20

22

24

Quench current test

Iq=16.37 kATop=6.79KBmax=3.6T

1kA/s

0.5 kA/s

Measured Iq =16.37kA (at 6.79K,3.6T)Extrapolated Iq= 53.9kA (3.8 K,4.5T)accordingto above results

TF coil test

Two TF coils (after VPI) have been tested• The coil and coil case was cooled dawn successfully

thermal-hydraulic behavior of the TF coil wastested

• Resistance of in coil joints and coil terminal jointswas measured

• Coil exiting at operation relevant condition(B×I)was carried out.

• Coil quench current was measured.

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TF prototype coil in test facility

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TF prototype coil cool down

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TF coil exciting

17.62kA Bmax4T T2c=6.55K

I=15kA at Tout=7.12K

Iq=15.6kA B=3.9T T=6.9K

Extrapolated Iq from the test results =55-65kA at Bmax=5.8T,T=3.8K

Vacuum Vessel & in vessel components

• Full welded double wall structure.• Sixteen horizontal ports and thirty two vertical ports for

Diagnostic, auxiliary heating and current drive• Divertor and limit armed by graphite and CFC tiles• Passive stabilizers and fast feed back control coils.• The vessel and first wall can be back up to 200 o C and

350 o C respectively.• Active cooling for first wall components and vessel wall.• Flexible gravity supports are adopted to compensate

thermal expansion.

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Vacuum Vessel

In vessel components

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Prototype of Vacuum Vessel Sector manufacture

Stress measurement ofVacuum Vessel portsand support

Vacuum Vessel port Bellows

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1/16 prototype vacuumvessel

Accuracy inspection of 1/16 prototype VV on A NC milling machine

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CryostatCryostat consists of upperhead, middle cylindricalsection and flat bottom sectionThe main functions of thecryostat is to provide thevacuum insulationenvironment for the operationof the superconducting coils,all of magnets, vacuum vesseland thermal shield aresupported on the flat bottomsection. Except 48 penetrationsfor the vacuum vessel portsextention, there are 19penetrations on the cryostatfor cryo-feeder line, access tothe cryostat interior for repairor inspection.

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VV and CS Thermal shield The thermal shields comprisethe vacuum vessel thermalshield which interposesbetween the VV and the magnetstructures , the cryostat thermalshield which surround the wallsof the cryostat and thetransition thermal shields thatenclose the port connectingducts . The main function ofthermal shield is to reduce thethermal radiation from vacuumvessel and cryostat to themagnets. All of thermal shield issandwich structure using two of3 mm thick steel panels on bothside and reinforced by 19×19square cooling pipe in between.The thermal shield will be cooled by60 K Helium.

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Thermal Shield fabrication

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1/8 of bottom Cryostatthermal shield

1/16 of prototype VVthermal shield

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Installation of device support structure

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Bottom cryostat installed on the support

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Pre-assembling

Cryogenic Systems

• The cooled mass is around 165 tons at 3.8-4.5K and 20 tonsat 80K. The heat load estimated is about 890W/4K +7.5g/sand 30kW/80K for normal operation.

• 110g/s-3.8K supercritical Helium flow for the PF coils cooling,260g/s-3.8K supercritical Helium flow will be used for TFwindings and coil cases cooling. 110g/s-60K Helium flow willbe used for thermal shield.

• The cryogenic system consists of 2kW/4.4K+11kW/80Krefrigerator, 260g/s-4bar He pump, 1000L-3.8K sub-coolerand 10000L-4.5K liquid He tank, gas storage system andcompressor station.

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CASIPP HT-7U

LN2

O RP

C1 C2

T1

T2

T3

4 . 4K

T4

Cu

rr

en

tleads

3.5 K

Thermal shield

19.5 bar

N2

He

300.0 K293.0 K 293.0 K

45.9 K

34.4 K

20.6 K

7 bar

0.37 bar

1 2 . 4K8.7 K

1.04 bar

6.4 K

T1

T2

T3

4.4 K3.5 K

148.5 g/s

210 g/s48.24 g/s57.4 g/s

1050 W

100 g/s

110 g/s

13 g/s0.47 bar

5 . 5 4K

4.5 bar

200 W Entropy

Temperature

Refrigeration cycleflow sheet of the refrigerator

3.5 K

CASIPP HT-7U

16 TF coils& 1st part ofTF cases

2nd part ofTF cases &structure

CS coils &PF7~8 &PF 13~14

PF9~10 &PF 11~12

4.5 K

SHe pump

Cooling of magnets

From J-T valve To oil ring pump

cool

dow

n

cool

dow

n

P=4.5 bar

cool

dow

n

Compressor station &Helium gas storage system

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Power Supply System•Thyristor converter has been designed for AC/DC conversion in TF Power supply and PF Power supply•Multi-stage forced commutation techniques and thyristor DC circuit switches are applied in PFPS to reduce the peakpower.• Thyristor and explosive actuated DC circuit breakers have been developed for quench protection.• High frequency H-bridge inverter for FPPF is undertaken.•The TF power supply and first set of PF power supply has been fabricated and tested. It is used for the coil test successfully.

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First set of test PF power supply system

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One set of PF power supply of HT-7U is used for coil test

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The converter output current:test result: 15kA,cross zero

smoothly

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The operation of switchnetwork unit

test result: current 15kA, voltage

2.4kV, switch times 3ms;

83 MW transformer substation for HT-7U

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ICRF & LHCD SystemThe LHCD System• 2.45 GHz existing system, which is used for HT-7

tokamak now, consists of 20 klystron amplifiers with CWoutput power of 2 MW in total.

• 3.7 GHz system consists of 2 klystron amplifiers with 1.5MW output power and 1000s pulse length.

The ICRF System Two subsystems, each one has 1.5 MW output power and

the frequency range is from 30MHz to 110MHz. The first1.5MW RF generator has been prepared and in benchtest now.

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1.5MW/30-110MHz RF generator

1MW 2.45GH LHCD launcher

2MW LHCD power supply

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Summary• The engineering design and entire preconcerted

R&D program has been carried out. • Cryostat, 1/16 of prototype of Vacuum Vessel and

Thermal Shield are fabricated and delivered toASIPP already. All of components will becomplated in the beginning of next year.

• The prototype CS coil and TF coil has been testedThe results shows that all of the magnets can bemeet the design requirement. The SC Magnetfabrication is going on smoothly.

• It is hopeful to finish machine assembly in 2005.

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