Document

Report
Tokamak and Tokamak related Diagnostic
Experience in India
Parameswaran Vasu
[email protected]
Institute for Plasma Research
Gandhinagar, INDIA
Web site:http://www.ipr.res.in
1
Out line of the Talk
• Introduction to IPR
• Introduction to Indian Tokamaks
• Diagnostics Systems at IPR
• Summary
2
Where we are located
CAT
IPR
SINP
3
About the Institute
 The Institute for Plasma Research (IPR) – Located in village
 Bhat- a few kilometers from Ahmedabad Intnl. Airport
 Institute was established in 1986
 210 Scientist /Engineers
 TOTAL STAFF STRENGTH = 440
4
Objectives Of the Institute
 Experimental & Theoretical research
sciences & Nonlinear phenomena
 Physics
and
in
Technology of Magnetically
Plasmas
Plasma
Confined
 To stimulate plasma Research & Development
activities in the Universities and Industrial sector.
 Contribute in the training of plasma Physicists &
Technologists in the Country.
5
Indian Tokamaks
SINP
Major Radius R0(m)
Minor Radius a (m)
Toroidal Field BT (T)2.00
Plasma Current Ip (kA)
Pulse Duration (s)
Plasma Cross-section
Elongation
Triangularity
Configuration
Coils Type (TF & PF)
Current Drive & Heating
Vacuum vessel
Design & Fabrication
Installation
ADITYA
0.30
0.045-0.075
1.50
75
0.02-0.03
Circular
------Poloidal
250
0.25
Circular
--------Poloidal
Limiter
Limiter
Copper
SST-1
0.75
0.25
1.1
0.2
3.0
Copper
Water Cooled
----Ohmic Transformer-----(Iron Core)
(Air Core)
Conducting
Vessel with
Shell (Al)
Electrical break
M/S Toshiba
Indigenous
1987
1989
220
1000
Elongated
1.7-2.0
0.4-0.7
Double/single Null
Poloidal Divertor
Superconducting
4.5K
Ohmic/LHCD
(Air Core)
Vessel without
Break
Indigenous
2006
6
SINP Tokamak
Diagnostics
• Spectroscopy
• Microwave
interferometry
• Internal magnetic and
rogowskii coils
• Time of flight analyser
• Hard X-ray systems
for Runaway electrons
7
SINP Tokamak
Two Operational Regimes:
• Normal q regime ; q egde > 3
• Low q & ultra low q regimes; 0 < q egde < 2
Experiments 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 Runaway Electrons
by ECE
• Current holes, negative currents
have been observed
Experiments 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
8
ADITYA
Since 1989 …
Major Radius R0(m)
Minor Radius a (m)
Toroidal Field BT (T)
Plasma Current Ip (kA)
Plasma Cross-section
Configuration
0.75
0.25
1.50
250
Circular
Poloidal
Limiter
9
ADITYA discharge
10
ADITYA discharge
11
Diagnostics on ADITYA
 Spectroscopy, Visible to EUV
 Magnetic probes
 Impurity line monitors
 Langmuir probes
 Visible continuum
 Microwave
 ECE
interferometer
 Microwave reflectrometry
 Soft X-ray, Vert. and Hor.
 Lithium themal beam and
Arrays
laser blow off
 Bolometer array
 Limiter IR thermography
 HXR
 Thomson Scattering
12
Inward particle transport [NF 1993]:
• Net flux outward, differential flux bipolar
• Low freq (<20 kHz) flux inward
• Ionization driven drift instability
Inward
Outward
Net flux outward
13
Intermittency measured through
non-Gaussian PDF (PRL, 1992).
• First in
ADITYA
• Confirmed
worldwide
• New
perspective
-- intermittent/
bursty
transport
--IPO /
coherent
structures
14
Publications
[1] Phys. Rev. Lett. 69, 1375 (1992).
[2] Nucl. Fusion 33, 1201 (1993).
[3] Current Science 66, 25 (1993).
[4] IAEA (1993) Vol. 1, pp. 467-472.
[5] Phys. Rev. Lett. 73, 3403 (1994).
[6] Phys. Plasmas, 3, 2979 (1996)
[7] Phys. Plasmas 4, 2982 (1997).
[8] Phys. Plasmas 4, 4292 (1997).
[9] Pramana, 55, 727 (2000).
[10] Phys. Plasmas 10, 699 (2003).
[11] IAEA (1995) Vol.1, pp. 583-591.
[12] In Nonequilibrium Phenomena in Plasmas,
Springer, Dordrecht, (2005) pp. 199-218.
[13] Phys. Plasmas 12, 072520 (2005).
15
Thomson Scattering
7 Channels 100 GHz Interferometer
2.5
Shot No: 17982
Te : 304 eV
2.4
7
6
5
4
3
2
1
0
2.3
Log ( I )
Aditya #18920
at 65 ms
9
 ne dl ( 1014 cm-2 ) 8
2.2
2.1
2.0
-25
1.9
4
-1x10
0
4
1x10
4
2x10
4
3x10
4
4x10
4
5x10
4
6x10
4
7x10
-15
-5
r (cm)
5
15
25
4
8x10


plot- ---log I vs ( )2
16
SXR
Front view
Horizontal Array
36 detectors distributed in 2 arrays.
• X-ray energy range : 500 eV to 15 keV. Spatial
resolution : 1.5 cms.
• Temporal resolution : 10 microsecs.
Vertical Array
Side view
• Absorber foil technique for Te (100eV to 800eV)
17
SXR Tomographic pictures
18
Plasma Spectroscopy, IPR
Spectroscopy Group in IPR is involved in the following
diagnostics monitoring plasma emission in
Visible to
EUV wavelengths
• Halpha
• Visible Continuum
• Impurity monitoring
Using
• 1.0 m Vacuum Normal Incidence Spectrograph
• 1.5 m Vacuum Grazing Incidence Monochromator
• 0.3 m Vacuum EUV Survey Spectrograph
• 0.5 m Visible spectrograph
• 1.0 m Visible imaging (multi-track) Spectrograph
• Filters-PMT Assemblies
19
RESULTS
The existing Spectroscopic Diagnostic facilities are versatile
enough to be used in diverse situations encountered in
ADITYA operation and yield good quality data which have
been used in:
• Fluctuation studies
• Impurity Influx estimates
• Zeff measurements
• Profile reconstruction of emissivities
• Spectral line shape analysis
The results have been used to model our discharges using codes like
Tokamak Simulation Code (TSC)
20
Fluctuation
Shot no. 15061
4
2
0
-2
-4
f (kHz)
0
Mirnov
Signal in a.u.
amplitude (a.u.)
6
30
40
50
60
-0.5
-1
-1.5
-2
30
30
20
20
10
10
0
30
35
40
45
50
CIV
0
30
30
40
35
50
40
45
60
50
t(ms)
t(ms)
Fig.5: Time series analysis shows the presence of mhd oscillation (m=2) in CIV
signal
Time series analysis shows the
oscillations (~10 KHz) in CIV
emission correlating to MHD
oscillation (m=2) Mirnov signal.
Sawteething:
Cross
correlation
between SXR (from Core) and H
(from edge) shows 200 sec delay.
[ICPP Conf. (2004)]
21
60
(kA
) 50
shot 13012
shot 12888
Impurity Influx
40
P
I 30
20
10
0
1
4
x 10
Fe
0.8
XV
41.7 nm
4
3.5
3
Counts (a.u.)
Fe
XV
0.6
0.4
2.5
2
1.5
1
0.2
0.5
0
-10
0
10
20
30
40
50
Time
Time(ms)
(ms)
60
70
80
90
Reduction in Fe signal
following wall conditioning
100
0
2150
60
2200
2250
2300
2350
0
15
30
75
90
45
Time (ms)
Wavelength (A0)
Successive spectra (15 ms
apart): evolution of CIII and
CV ionization stages
Influxes from ADITYA surfaces (atoms/cm2 sec)
Species
Wall
Limiter
Hydrogen
1.0 x 1016
>1017
Oxygen
1.8 x 1015
2.0 x 1016
Carbon
1.7 x 1015
2.2 x 1015
22
Zeff measurements
Shot : 15345
19-Aug-2004 01:51:31 PM
1.8
1.6
1.4
Signal (a.u.)
1.2
1
0.8
0.6
0.4
0.2
0
-0.2
40 mv
0
Noise Level
50
100
150
Time (ms)
Visible continuum measurement:
Typical
intensities
~1011
photons/cm2.sr.nm.sec, 50 s time
resolution, S/N ~ 4
Zeff during a clean shot
estimated, and compared with
modelling
results
from
Tokamak Simulation Code
[PPCF (2004)]
23
Profile reconstruction of emissivities & Line Shape

30000
250
Measured
Total_fit
Cold_Comp_
Cold_Comp_
Cold_Comp_
Warm_Comp_
Warm_Comp_
Warm_Comp_
Hot_Comp
Residue
25000
20000
Intensity (a.u.)
15000
200
10000

5000
0
150
-

515 520 525 530 535 540
PIXEL
+
r/a = 0.9
100
50
0
655.9
656.0
656.1
656.2
656.3
656.4
656.5
656.6
656.7
Wavelength (nm)
Multi-track spectral data around H
from nine poloidal chords simultaneously;
OV, H and CII are seen
12
H, C II, O V, Normalised Emissivity (a.u.)
INSTRUMENTAL
WIDTH ~ 2 PIXEL
(He-Ne LASER)
300
10
8
6
H
4
C II
OV
2
0
-1.0
-0.8
-0.6
-0.4
-0.2
0.0
0.2
0.4
0.6
0.8
1.0
r/a
Analysis of H line shape shows
presence of multi-temp. components
of Hydrogen atoms in the plasma
edge
Inversion of above data shows
emitting regions of H, CII and
OV at plasma edge
24
Analysis of spectra with CR Model
ADITYA wall conditioning often uses a helium discharge by ECR, upon
which periodic Ohmic Pulsed Discharges (PD) are superimposed (4 ms
every 4 s)
ECR+PDC
ECR
Normalized HeI Line Intensity
1.0
0.8
0.6
0.4
0.2
0.0
500
600
700
800
900
1000
Major Axis in mm
ECR
plasma
(Te~17eV,
Ne~7.5x1010 cm-3) is confined to
a narrow region, while during
PD, the plasma (Te~8.5eV,
Ne~9x1011 cm-3)
cross section.
fills
vessel
Analysis of spectral data using a
Collisional Radiative (CR) Model
code to infer Te and Ne that ‘best fit’
the Helium line
(2005)]
intensities [JAP
25
ADITYA simulations using TSC
• Total eight shots were chosen for modeling. Typical parameters :
R/a=0.75/0.25m, BT=0.75T, Ip~65-75kA, density~1.2-2 x1013/cc,
discharge duration 75-95 msec, negligible hard X-ray during flat top
• Inputs to TSC :
Plasma and vessel geometry, experimental OT and BV currents.
But FB applied on these currents to force TSC follow experimental
Ip and Rp. Hence the differences between experimental and
simulated values are to be considered as error in the simulations.
 experimentally measured central and edge densities. Density
profile chosen as ne(ψ,t)=ne0(t)(1- ψβ)α+nb. α=1, β=2 chosen for all
shots
 Impurity concentrations
26
TSC simulation
results of
ADITYA shot
#12308
27
TSC simulation results (other parameters)
Impurity charge states
t=20 msec
#12486
Te,i profiles
Current profile
Flux
t=60surfaces
msec
χe,i (m2/s)
ψ
28
Publications
[14] “Modelling of Ohmic
discharges in ADITYA
tokamak using Tokamak Simulation Code”, Plas.
Phys. & Cont. Fus., 46, 1443 (2004).
[15] Optimization of the number of soft x-ray arrays and
detectors for SST-I Tokamak by the tomographic
method. Rev. Sci. Ins., 74, 2353 (2003).
[16] Superiority of Bessel function over Zernicke
polynomial as base function for radial expansion in
tomographic reconstruction. Pramana, 61, 141
(2003)
[17]"Characterization of Helium Discharge Cleaning
Plasmas in ADITYA Tokamak Using collisional
radiative-model Code", Jnl. App. Phys. (2005).
[18] “Exploring core-to-edge transport in Aditya tokamak
by oscillations observed in the edge radiation” Proc.
12th International Congress on Plasma Physics
(ICPP), held during October 25-29, 2004 at Nice,
France.
29
OBJECTIVES:
• Study Physics of Plasma Processes in tokamak
SST-1 : A steady state
superconducting tokamak
under steady-state conditions.
• Particle Control (fuel recycling and impurities)
• Heat removal
• Divertor Operation (radiation, detachment , pumping etc )
• Current maintenance
–LHCD, Bootstrap, advanced configurations
• Learning new Technologies relevant to steady state
tokamak operation:
• Superconducting Magnets
• Large scale Cryogenic system (He and LN2)
• High Power RF Systems
• Energetic Neutral Particle Beams
• High heat flux handling
30
Status:
• SST-1 assembly has been completed. Commissioning is in progress.
• Integrated operation of the Cryogenic system with magnets and thermal
shield have been carried out and distribution of cryogens have been
checked.
• Cooling of thermal shields up to 80K and of magnets up to 70K has been
achieved.
• Leaks in the cryogenic distribution were observed and prevented further
cool down of magnets. The leaks have been identified and repaired.
• Modifications of the Liquid Nitrogen distribution Has been completed to
achieve uniformity in temperatures at different thermal shields.
• In-vessel and other first phase diagnostics have been integrated to SST-1.
• Next cool down scheduled to start in two months.
31
DIAGNOSTICS ON SST-1
• Electromagnetic Sensors
• Rogowskii Coils -- Plasma current &
Halo Current
• Mirnov Coils -- Magnetic
Fluctuations & Eddy Currents
• Magnetic Probes -- Plasma position
and shape measurements
• Saddle Loops -- Locked mode
detection
• Fiber Optic Current sensors -Plasma current
• Hall Probes -- Plasma current and
position
• Flux Loops -- Loop Voltage
• Diamagnetic Coils -- total stored
energy
• Langmuire Probes Divertor Plasma
• Far Infrared Interferometers -Density measurement and Control
•Vertical , Lateral and Tangential
• Electron Cyclotron Emmission
• Radiometer
91-130 GHz
• Fast Scanning Fourirer Transform
Michelson Interferometer 75-1000 GHz
• Thermography
• Thomson Scattering
• X-Rays
• Soft X-Ray imaging; Hard X-Ray
Monitors; Vacuum Photodiode Array
• Motional Stark Effect
• Spectroscopy
Passive : Visible/UV/VUV
32
Active : HNB based CXRS & MSE
Summary
• I P R has built Aditya & SST-1 Indigenously
• Developed & Installed various diagnostics in
Aditya
• Design & Procurement of diagnostics systems for
SST-1 is underway.
In India we have a big diagnostics group with first
hand experience in:
• Designing and putting together a variety of optics
and spectroscopy based diagnostics, and
• The analysis of data from such diagnostics
Which will enable us to execute effectively the ITER
related diagnostics responsibilities we undertake
33
Thank you
34
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