Determining of Radial Profile of Hydrogen Determining of Radial Profile of Hydrogen Isotope Composition of TCV plasmas Isotope Composition of TCV plasmas A.Karpushov, B.P.Duval, Ch.Schlatter, H.Weisen with contribution from Laboratory of Atomic Collision Physics, Ioffe PTI for 32 nd EPS Conference on Plasma Physics, 27 June - 1 July 2005, Tarragona, Spain Centre de Recherches en Physique des Plasmas Association Euratom – Confėdėration Suisse, Lausanne, Switzerland RS TCV, Friday, June 3, 2005
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Determining of Radial Profile of Hydrogen Isotope Composition of TCV plasmas A.Karpushov, B.P.Duval, Ch.Schlatter, H.Weisen with contribution from Laboratory.
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Determining of Radial Profile of Hydrogen Determining of Radial Profile of Hydrogen Isotope Composition of TCV plasmasIsotope Composition of TCV plasmas
A.Karpushov, B.P.Duval, Ch.Schlatter, H.Weisen
with contribution from Laboratory of Atomic Collision Physics, Ioffe PTI
for 32nd EPS Conference on Plasma Physics,
27 June - 1 July 2005, Tarragona, Spain
Centre de Recherches en Physique des PlasmasAssociation Euratom – Confėdėration Suisse,
Lausanne, Switzerland
RS TCV, Friday, June 3, 2005
32nd EPS Conference on Plasma Physics, 27 June - 1 July 2005, Tarragona, Spain2
Introduction. Direct measurement of plasma hydrogen isotope neutral particle emission has been used to study particle transport in TCV. A Compact NPA (CNPA), with mass and energy separation has, been used to obtain information on accumulation, propagation and relaxation of hydrogen particles in a deuterium background plasma using programmed H-gas puffs. A series of thermal hydrogen gas injections into a deuterium background plasma, with a simultaneous switch-off of the main deuterium gas injection, leads to partial replacement of deuterium ions by hydrogen. A recovery algorithm has been designed to get information on the temporal behaviour of the radial hydrogen density profile. Algorithm uses the measured electron temperature and density profiles (TS), ion temperature profiles (CXRS), information on Zeff profiles and numerical modelling of neutral
density profiles and energy spectrums of neutrals escaping plasma with DOUBLE and KN1D codes.
32nd EPS Conference on Plasma Physics, 27 June - 1 July 2005, Tarragona, Spain3
M 410: M 410: “Effects of plasma shape on tokamak operational space and performance” “Effects of plasma shape on tokamak operational space and performance” Jaunt 414: Jaunt 414: “Ion transport”“Ion transport”p 414-1: p 414-1: “H-gas puff experiments on TCV”“H-gas puff experiments on TCV”
Method: Modulated hydrogen gas injection in deuterium plasma. Measurement of temporal variations of energy spectra of neutral hydrogen isotope fluxes: Jcx
H,D(E,t).
Reconstruction of temporal behavior of hydrogen isotope radial profiles: nH,D(). Calculation of transport parameters (DH,D,VH,D,H,D) and Analysis of their dependences on plasma parameters (ne,Te, shape) - tbd.
M414
32nd EPS Conference on Plasma Physics, 27 June - 1 July 2005, Tarragona, Spain4
counting with pulse amplitude discrimination Acquisition time resolution 0.5-4 msMax. count rate 800 pulse/ms
hardware
32nd EPS Conference on Plasma Physics, 27 June - 1 July 2005, Tarragona, Spain5
experimental scenario
A series of thermal hydrogen injection (duration of 10-100ms and period of 150-500ms) in background plasma with simultaneous switch-off main deuterium gas injection leads to partial replacement of deuterium ions by hydrogen
Plasma current, 150 kA
TS nemax: 4x1019m-3
FIR nl: 1.4x1019m-2
TS Temax: 900eV
CNPA Tieff: 400eV
Safety factor
Gas injection, mbarl/secHydrogenDeuterium 5
CNPA countrates deuterium, counts/2.5ms
CNPA countrates hydrogen, counts/2.5ms
The CNPA views the TCV plasma along horizontal view-line thought plasma axis for Zo=0
32nd EPS Conference on Plasma Physics, 27 June - 1 July 2005, Tarragona, Spain6
NPA countrate (N) energy spectrum of atomic flux (J(E))
detection efficiency
dzvvEfnnSEJa
a
iaiacxiia
)()()(plasma parameters energy spectrum of atomic flux (J(E))
attenuation
“CX spectrums” for Ho and Do in TCV deuterium discharge
Following H-gas puff, count-rates in the CNPA hydrogen channels (ch.1-5: 0.6-4keV) increase by a factor of 3-4 and counting rates in deuterium channels(ch.12-20: 0.5-6keV) decrease by ~1/2.
emissivity (E,z)
32nd EPS Conference on Plasma Physics, 27 June - 1 July 2005, Tarragona, Spain7
DOUBLE-TCV code
0
200
400
600
800
1000
Te
,Ti,
eV
P lasma profiles for #29601 @0.75s
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10
1
2
3
4
5x 10
19
psi
n,
m-3
ne
ni
HD
C
Te
Ti
DOUBLE-TCV: Simulation of CX fluxes emitted by tokamak plasma (Maxim Mironov, A.F.Ioffe PTI, March 2005)
The code uses the same Monte-Carlo technique to calculate neutrals distribution in plasmaAssumes that plasma is surrounded by homogenous atomic gasNeutral beam injection (NBI) included
H and D CX-spectrums before H-puffnH/nD:[5.6-7.8]%
500 1000 1500 2000 2500 3000 3500 4000
1025
1026
1027
1028
1029
E, eV
Fd
c
H puff in #29601 @0.786 sec
005-007 ms
007-010 ms010-015 ms
015-020 ms
020-025 ms
025-030 ms030-040 ms
040-050 ms
CX-spectrums of H-ion population created by H-puff
32nd EPS Conference on Plasma Physics, 27 June - 1 July 2005, Tarragona, Spain10
recovery algorithm
0 0.2 0.4 0.6 0.8 10
0.5
1
1.5
2x 10
18
psi
n H,
m-3
Base functions from 'base 29601 XXX.mat'
500 1000 1500 2000 2500 3000 3500 4000 4500
1024
1026
1028
E, eV
Fd
cAssume a hydrogen density distribution as a linear combination of density base functions and build basefunctions.
i
baseiiH nkn
Dbasei nn with
nH/nD=const
nH/nD(=0)=0
nH/nD(=1)=0
i
baseiidc FkF mod
For each nibase calculates CX-spectrums (Fi
base)Model CX spectrum is a linear combination of “base CX-spectrums” with same ki
k kdc
kdckdc
EF
EFEFexp
expmod
Fond ki from minimisation of difference between “model” and “experimental” CX-spectrums
Density base functions
CX-spectrum base functions
32nd EPS Conference on Plasma Physics, 27 June - 1 July 2005, Tarragona, Spain11
results
CX-spectrum and density profile at 5-7 msblack – result, colours – ki “base functions”
400 600 800 1000 1200 1400 1600 1800E, eV
Fd
c
#26001 @ 5.00-7.00ms
0 0.2 0.4 0.6 0.8 10
0.5
1
1.5
2x 10
17
psi
n H,
m-3
1000 2000 3000 4000 5000 6000
1024
1026
1028
1030
E, eV
Fd
c
#26001 @ 10.00-15.00ms
0 0.2 0.4 0.6 0.8 10
1
2
3
4
5
6
7x 10
17
psi
n H,
m-3
CX-spectrum and density profile at 10-15 msblack – result, colours – ki “base functions”
32nd EPS Conference on Plasma Physics, 27 June - 1 July 2005, Tarragona, Spain12
results
500 1000 1500 2000 2500 3000 3500 4000
1026
1028
E, eV
Fd
c#26001 @ 30.00-40.00ms
0 0.2 0.4 0.6 0.8 10
1
2
3
4
5
6x 10
18
psi
n H,
m-3
500 1000 1500 2000 2500 3000 3500 4000
1026
1028
E, eV
Fd
c
#26001 @ 100.00-125.00ms
0 0.2 0.4 0.6 0.8 10
2
4
6
8
10
12
14x 10
17
psi
n H,
m-3
CX-spectrum and density profile at 30-40 msblack – result, colours – ki “base functions”
CX-spectrum and density profile at 100-125 msblack – result, colours – ki “base functions”
32nd EPS Conference on Plasma Physics, 27 June - 1 July 2005, Tarragona, Spain13
results
0 0.2 0.4 0.6 0.8 10
2
4
6
8x 10
18
psi
n H,
m-3
H puff in #29601 @0.786 sec
0 0.2 0.4 0.6 0.8 10
0.05
0.1
0.15
0.2
0.25
psi
n H/n
D,
m-3
H puff in #29601 @0.786 sec
005-007 ms
007-010 ms010-015 ms
015-020 ms
020-025 ms
025-030 ms030-040 ms
040-050 ms
005-007 ms
007-010 ms010-015 ms
015-020 ms
020-025 ms
025-030 ms030-040 ms
040-050 ms
500 1000 1500 2000 2500 3000 3500 4000
1025
1026
1027
1028
1029
E, eV
Fd
c
H puff in #29601 @0.786 sec
005-007 ms
007-010 ms010-015 ms
015-020 ms
020-025 ms
025-030 ms030-040 ms
040-050 ms
density profiles during H-puff CX-spectrums during H-puff
During H2-puff, the nH/nD ratio evolves from a hollow radial profile (<20ms) to a flat profile (20-25ms). After puff switch off hydrogen accumulated in internal region.
32nd EPS Conference on Plasma Physics, 27 June - 1 July 2005, Tarragona, Spain14
results
density profiles after H-puff CX-spectrums after H-puff
0 0.2 0.4 0.6 0.8 10
2
4
6
8x 10
18
psi
n H,
m-3
H puff in #29601 @0.786 sec
0 0.2 0.4 0.6 0.8 10
0.05
0.1
0.15
0.2
0.25
psi
n H/n
D,
m-3
H puff in #29601 @0.786 sec
040-050 ms
050-060 ms
060-070 ms
070-080 ms080-090 ms
090-100 ms
100-125 ms
040-050 ms050-060 ms
060-070 ms
070-080 ms
080-090 ms
090-100 ms100-125 ms
500 1000 1500 2000 2500 3000 3500 4000
1025
1026
1027
1028
1029
E, eV
Fd
c
H puff in #29601 @0.786 sec
040-050 ms
050-060 ms
060-070 ms
070-080 ms080-090 ms
090-100 ms
100-125 ms
With successive H-puffs, the hydrogen profile becomes peaked; hydrogen “accumulation” in internal regions takes place. “Confinement time” for low density, low current L-mode discharges was 15-25ms.
32nd EPS Conference on Plasma Physics, 27 June - 1 July 2005, Tarragona, Spain15
results
0 1 2 3 4 5 6 7
0
1
2
3
4
5
6
-grad(nH)/n
H, m-1
H
/nH
, m/s
# 2 9 6 0 1 VH
:-0 .3 5 m /s DH
:0 .8 3 m 2 /s for :[0 .3 5 :0 .6 5 ]
VnnD To explain H-puff results from TCV, a plasma pinch must be considered.An estimation of effective diffusion coefficient yields a value ~1m2/sec, pinch velocity is ~1m/s for dn/dt1020 m-3sec-1
32nd EPS Conference on Plasma Physics, 27 June - 1 July 2005, Tarragona, Spain16
results
H-puff
EE
EJEF
cxdc
)(
)()(
NPA data analysis“CX spectrum”:
1
ln)(
EFdE
dET dc
effNPA – effective NPA ion temperature
)(
)()(
det EEt
ENEJ
NPA countrate (N) energy spectrum of atomic flux (J(E))
dzvvEfnnSEJa
a
iaiacxiia
)()()(plasma parameters energy spectrum of atomic flux (J(E))
“CX spectrums” for Ho and Do in TCV deuterium discharge
Subtraction of interpolated “background” from hydrogen “CX-spectrum” allows to get temporal behavior of NPA “CX-spectrum” and ion temperature of additional hydrogen population created due to H-gas injection.
Energy spectra of additional hydrogen population relaxes to background Maxwellian CX-spectra in 10-30 ms. (Ion-Ion local thermal equilibration time < 1 ms)
hydrogen and deuterium interpolated “background”and subtracted additional hydrogen population
effective CNPA ion temperaturefor E[0.5 3.0keV],error bars ~15%
detection efficiency
attenuation
32nd EPS Conference on Plasma Physics, 27 June - 1 July 2005, Tarragona, Spain17
Response time () of NPA counrates on H-puff increases with increase of plasma density
32nd EPS Conference on Plasma Physics, 27 June - 1 July 2005, Tarragona, Spain18
discussion
V I Afanasyev, A Gondhalekar, and A I Kislyakov, “On the Possibility of Determining the Radial Profile of Hydrogen Isotope Composition of JET Plasmas, and of Deducing Radial Transport of the Isotope Ions”, JET report JET–R(00)04 (Oct. 2000)
TCV result is contradictory to the observation of deuterium transport in hydrogen plasma observed on JET with short pulses of D2 gas injection (JET discharge #43446), where the nD/nH ratio
was hollow during and after gas injection. Such behaviour of radial profile of hydrogen isotope ratio probably can be explained by dependence on mass pinch velocities and ion diffusion coefficients.
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10
0.05
0.1
0.15
0.2
0.25
psi
n H/n
D,
m-3
H puff in #29601 @0.786 sec
32nd EPS Conference on Plasma Physics, 27 June - 1 July 2005, Tarragona, Spain19
limitations
Analysis of H propagation in TCV plasma with high current and high density is “difficult” due to effects of sawtooth activity.
In CNPA measurement a plasma centre can not be resoled due to low NPA counting rates at high energies (>3-4keV); high is limited by a low energy limit of NPA (Ti(=1)~30eV)
“GOOD”L-mode, OHTe > 400 eV, NL<3x1019m-2
“BAD” sawtooth ELMs + H-mode X2 ECH non-Maxwellian F(E) High density
Ip:340kA, FIR nl: 3.2x1019m-2,
TS ne:5.5x1019m-3, Te=1keV
32nd EPS Conference on Plasma Physics, 27 June - 1 July 2005, Tarragona, Spain20
summary
1) CNPA was successfully tested as tool to measure hydrogen isotope composition.
2) A recovery algorithm of hydrogen isotope ratio radial profile from NPA measurement was developed and tested for TCV.
3) A density profiles can be recovered for TCV L-mode, low density, low current discharges.
4) Ion transport coefficients are in reasonable agreement with other observations on TCV (D~1m2/sec, V~-1m/s).