Status of SST-1 Project and Fusion
Research in India
Yogesh C. Saxena
Institute for Plasma Research
Gandhinagar, INDIA

Plan of Talk
• Fusion Research In India– ADITYA Tokamak– SINP Tokamak• SST-1 tokamak– Objectives– Parameters– Description of Sub-systems & Fabrication Status

Indian Tokamaks

Major Radius
R0Minor RadiusaToroidal Field
BT
Plasma Current
Ip
Pulse Duration?
Plasma Cross-section
Configuration
Coils Type (TF & PF)
Current Drive & Heating
Vacuum vessel
Design & Fabrication
Installation

ADITYA

SINP Tokamak

0.75 m0.25 m1.50 T
250 kA
250 msCircular
Poloidal Limiters
Copper Water cooled
Ohmic Transformer(Air Core)
Vessel with Electrical breakIndigenous
1989

0.30 m
0.075 m2.00 T
75 kA
20-30 ms
Circular
Poloidal Limiters
CopperOhmic transformer(Iron Core)
Conducting Shell
M/S Toshiba, Japan1987

ADITYA TOKAMAK• Regular operations with transformer-Converter power system. 80-100 kA ; 100
ms plasma discharges at 8.0 kG field are being studied. Standard Diagnostics havebeen developed and deployed.
•Magnetic flutuations have been studied using Single value decomposition
technique.
•Edge fluctuations and turbulence in density and potential have been investigated.

• Pdf are found to be non-Gaussian ; turbulence exhibits intermittency•Low frequency (< 50 kHz) contribute to convective particle transport•Turbulence exhibits complex, chaotic spatial and temporal variation.

• Coherent structures have been obtained.in potential fluctuations using
conditional averaging techniques. The dynamics of the structures suggest
mechanism of “bursty” transport of edge plasma.
•Coupling coefficients and coherencies have been obtained using Wavlet
analysis to study the power transfer due to linear,mixed and quadraticcoupling.

ADITYA TOKAMAKUpgradation:• A 20-40 MHz 200 kW ICRH system has been added.

•A 28 GHz 200kW Gyratron based ECRH system is commissioned.
•Additional Diagnostics have been implemented:•Thomsom Scattering system•Spectroscopy ( GIM, 10-600nm; NIM, 100-300 nm; VIS 300-800 nm)•Electron Cyclotron Emission measurement•Soft X-ray Camera

SINP Tokamak
Two Operational Regimes:•Normal q regime ; q egde > 3•Low q regime; 0 < q egde < 2Experiments in low q regime:•Accessibility condition for VLQ and ULQ regimes•Anomalous Ion heating in VLQ discharges•Edge Biasing experiemts in VLQ dicharges•Runaway Electrons in startup phase of VLQ discharges•Variation in Up-down asymmetry with edge safety factor

SINP TokamakExperiments in normal q regime:•Drift wave like instability in Tokamak core region.
•Anomalous current penetration•Temperature fluctuation induced anomalous transport•Origin of inversion of up-down potential assymetry•Observation of ringing toridal current exlinable by Helicity
conservations•Observation of Runaway Electrons by ECE

Proposed to add LHCD on the tokamak in near future.

OBJECTIVES:•Maintaining shaped, double/single null plasmas
with non- inductive Current drive & auxiliary
heating•Steady state operation with controlled particle andpower exhaust•Advanced Tokmak Configurations with bootstrap
current•Learning new Technologies relevant to steady statetokamak operation:•Superconducting Magnets•Large scale Cryogenic system (He and LN2)•High Power RF Systems•Energetic Neutral Particle Beams•High heat flux handling

3-D Cut View of SST-1

SST1 MACHINE PARAMETERS••••••••••

MAJOR RADIUSMINOR RADIUS
ELONGATIONTRIANGULARITY
TOROIDAL FIELD
PLASMA CURRENTASPECT RATIOSAFETY FACTOR
AVERAGE DENSITYAVERAGE TEMP.

: 1.1M: 0.2 M: 1.7-2: 0.4-0.7: 3T: 220 kA.
: 5.2:3: 1X 1013cm-3: 1.5 keV••••••••••PLASMA SPECIES: HYDROGEN
PULSE LENGTH: 1000s
CONFIGURATION: DOUBLE NULL:: POLOIDAL DIVERTERHEATING & CURRENT DRIVE:LOWER HYBRID: 1.0 MWNEUTRAL BEAM
: 0.8 MW
ICRH
: 1.0 MWTOTAL INPUT POWER : 1.0 MW
FUELLING: GAS PUFFING

3-D Cut View of SST-1

SST-1 MAGNET SYSTEM
Requirements:• Confinement, Shaping and Equilibrium Fields•Ohmic Flux Storage•Feed-Back Control

Supercondcting Magnets:•Toroidal Field (TF) Coils :16 Nos.

• Poloidal Field (PF) Coils :9 Nos.

Copper Magnets (Water Cooled) :•Ohmic Transformer (TR) Coils :7 Nos.

•Poloidal Field (PF ) Coils ( in-Vessel): 2 Nos.
•Position Control Coils ( in-Vessel): 2 Nos.

Conductor for SST-1 Superconducting Magnets
Strand Characterstics
Material: NbTi in Cu
Strand Diameter: 0.86 mm
Filament Dia.
: 10 µm
Filaments per strand : 1272
Cu : NbTi:: 5:1
Cu RRR: 100
Ic@4.5K; 5T: 232A
Index ‘n’: 45
Hysterisis Losses: 33.5 mJ cm-3

Conductor Characteristics
Conductor type
: CICC.
Outer Dimensions: 14.8× 14.8 mm2.
No. of Strands: 135.
Cabling Pattern: 3? 3? 3? 5.
Last stage wrapped (half overlap) with
25 ? m thick SS304 tape.
Twist Pitches:––––

I stage : 40 mm
II stage : 75 mm
III stage: 130 mm
IV stage: 290 mm

Conduit Material
Conduit thicknessVoid Fraction
Ic @ 5T, 4.5K
Iop @ 5T, 4.5K

: SS 304L.
: 1.5 mm.
: ? 36 %.
: 36 kA.
: 10 kA.

SST-1 TOROIDAL FIELD COILSTF COIL Winding Pack:

PARAMETERS OF TF COILS:• Modified D-Shape• Base Conductor: NbTI based CICC

•Total No. of Coils :16• 6 # of Double pancakes•Turns per Coil :108• Cross-section : 194x144 mm2•6 Double Pancakes with 9 turns per pancake•Current per turn (3T Field at Plasma Center): 10 kA•Maximum Field at Conductor:

5.1 T•Maximum Field Ripple :0.35%•Total Inductance (16 Coils in series) :1.12H•Total Stored Energy:

56MJ•Dump Time Constant:

12 s•Peak Dump Voltage:± 600VSST-1 Poloidal Field Coils
Design Drivers:•Support single & double null equilibria with wide range of Triangularity ( 0.4-0.7),
Elongations ( 1.7-1.9), li (0.75 -1.4), ? p ( 0.01-0.85) & slot divertor configuration•Limiter operation during Plasma current ramp up

Parameters of PF Coils

Coil
#Coil
Verticaltype coils Radius Location(m)(m)
PF1PF2PF3PF4PF5PF61222220.45
0.45
0.50
1.72
2.01
1.35

0.0? 0.43? 0.93? 1.03? 0.65
? 0.35#Winding
Cross- turns
section(mm2)
71x3208071x163
40136x380 192
85x1364085x136
40100x100 16

SST-1 OHMIC TRANSFORMER
Design Drivers:• Stress limited maximum flux storage•Matching to existing power supply•Plasma Break down and initial plasma current
ramp up

Characteristics:• Water cooled copper coils•Stored Flux : 1.4 Vs @ 20 kA per turn•Maximum Field in plasma Volume : 18 GCoils#Radius(m)Turns(#)

Xsection(mm2)Center(m)TR1

10.20672120? 260
00.00

TR220.49

40

195 ? 95?? 1.40

TR322.42358 ? 23?? 0.73

Fabrication of Magnetic Field Coils

Manufacturing of Magnetic Field Coils

SST1 Vacuum Vessel & Cryostat
Vacuum Vessel parameters•

VESSEL MAJOR RADIUS: 1.285 m•

VERTICAL SEMI AXIS

: 0.81m•

RADIAL SEMI AXIS

: 0.53 m•

POLOIDAL LENGTH: 4.4 m•NO. OF MODULES: 16

Cryostat parameters:
Vertical Height: 2.6 mOuter Diameter: 4.4 mInner Diameter: 0.355 m

Wall Thickness: 10 mmTotal Surface Area

: 59 m2

Total Volume: 39 m3

Total Weight: 4520 kg•

NO. OF TOP PORTS: 16•

NO. OF BOTTOM PORTS: 16•

NO. OF RADIAL PORTS: 16Material: SS 304L•TOTAL SURFACE AREA

: 75 m2

No.of Modules:8•

TOTAL VOLUME: 16 m3•

TOTAL WEIGHT: 4100 kg•MATERIAL: SS 304L•

VACUUM:10-8mbar

Fabrication of SST1 Vacuum vessel andCryostat

PUMPING SYSTEM FOR SST-1 TOKAMAKNORMAL PUMPING OF VACUUM VESSEL:• Out gassing gas load ? 1 x 10(-4) mbar l/s• Design base pressure ? 1 x 10(-8) mbar
• Required pumping speed ? 10,000 l/s• 2# TMP each ( 5000 l/s)
• 2# of Cryopumps (10,000 l/s)

DIVERTOR PUMPING OF SST-1 TOKAMAK:•Particle exhaust requirement : 22 mbar l/s at 1×10(-3) mbar
•Required pumping speed: 22000 l/s for hydrogen•Design value of pumping speed : 44600 l/s for hydrogen•16 # TMP ( 5000 l/s) ; on top and bottom ports

CRYOSTAT PUMPING:• Out gassing gas load ? 5 x 10(-2) mbarl/s at 300 K•Design base pressure ? 1 x 10(-5) mbar
•Required pumping speed ? 5,000 l/s•2# TMP ( 5000 l/s) on Cryostat ports

Plasma Facing Components of SST-1
Design Drivers:•Steady state heat and particle removal•1 MW power Input•Surface temperature ? 1000 0C•Baking up to 350 0C•Electromagnetic forcesss during VDE,
disruptions and halo currents•Modularity•Isostatically pressed, low ash content,Graphite•Tiles mechanically attached to High strength
copper alloy (CuZr & Cu CrZr) backplate;•Cooling tubes (SS304) embedded in & brazedto the back plates.

SST-1 LHCD SYSTEM
Frequency: 3.7 GHz.
Power ( 2 klystrons each of 500 kW CW): 1 MW
Antenna type: Grill# of subwaveguides: 32 x 2rows
Periodicity (with 2mm thick septa): 9 mmSubwaveguide opening: 76 x7 mm2
Design NII (at 90o phasing): 2.25
NII variation (from 40o to 60o phasing) : 1.0 - 4.0
Klystron input power: 10Watt

SST1 ICRH System
PARAMETERS
Frequency Range: 22.8 - 92 MHzPower: 1.5 MWNo. of Antenna:4#Duration: 1000 sec
Tx-Line system: 9" water cooled
Coupling efficiency : 80 – 9245.6 MHz for 2 ? ce heating at 1.5 T
91.2 MHz for 2 ? ce heating at 3.0 T
22.8 MHz for DD- Minority heating at 3.0 T
24.3 MHz for IonIon-Ion Hybrid resonance at 3.0 T
Two generators of 1.5 MW each to cover thefrequency range

SST1 ECRH SYSTEM
Objectives:• PrePre-Ionisation & Plasma start up• Electron Cyclotron Heating to assist Current drive during LHCD

Main Parameters• Gyratron Frequency : 82.6 GHz•Output Power: 200 kW CW•Output Mode: HE-11•Operating TF Field :•Fundamental : 3 T•2nd Harmonic : 1.5 T•Exit dimensions of Waveguide :63.5 mm

NEUTRAL BEAM INJECTION SYSTEM
Objectives:
For SST-1:•Heating and Current Drive•Fuelling•Momentum Injection
On Test Stand:•Long Pulse Operation•Data Base Generation

Parameters:
Injection

Co-TangentialSpecies

H/D ( He on Teststand)Beam Voltage

20 - 80 kV

Beam Power

0.3 - 1.7 MW

Ion Source

Multipole Bucket TypeBeam Divergence<1

Number of Beam Line 1
Number of Sources1

Duti Factor

1000s on 5000s off

Pumping

Cryo-condensation
pumps @3.8K

Chevron Baffle for Cryo-pump

Helium Cryogenic System
Heat Loads & Cooling Requirements:• Steady State Heat Loads: 180 W

•Energy input to SCMS

: 125 kJ

•Current leads: 150 l/hr

Features of He Plant•Fully automated refrigerator/liquefier•400 W for SCMS + 250 W for Cold
Circulation Pump
•200 l/h Liquefaction for Current leads•Equivalent nominal power 1350 W@4.5K•2500 l capacity Master Control Dewar•Cold Circulation Pump with Heat exchangers•300 g/s flow of SHe through SCMS:•4.5K, 4.0 bar(a) Inlet to SCMS; <5.0K,> 3.0 bar(a) at outlet to SCMS

Erection of Helium PlantINTEGRATED FLOW DISTRIBUTION & CONTROL SYSTEMIFDCS links the He Plant to SCMS
•Supercritical He flow through TF coils, PF coils, TF casings & Cold Bus Duct
•Liquid Helium Supply to Current leads . Provision for SHe supply to test chamber

IFDCS PID

Valve Box Schematics

LN2 & Gas Management System
LN2 Requirements (1.5 bara; 79K):•Radiation Shield : 350 l/h – 1450 l/h•CLB, Cryo-transfer lines: 95 l/h•Liquid Helium Plant : 110 l/h•On-line Purifier :110 l/h•NBI system : 225 l/h – 400 l/h

LN2 Storage & Dostribution:•3# tanks 35 m3 each (105 m3 Total)•Max operating pressure 2.75 bar g•Max Discharge rate 2000 l/h•Main Transfer Lines ( 250 m )•Phase separator/ Sub-cooler Dewar•LN2 Distribution and Return lines•N2 Gas vent lines

High pressure storage system:•2# of 25 m3 SS tanks at 150 bar
Medium Pressure storage system:•4# of 68 m3 tanks at 14 bar.
Gas Recovery system:•2# of 40 Nm3 gas bags
•1 g/s recopvery compressor @150 bar•PurifierFoundation and support structure

TF Coil Assemly Mock Up

TF Coil Vessel Sector Assemly Mock Up

Current LeadBus DuctThanks for your kindattention