globus-m results toward compact spherical tokamak with ... · /qr ohmic l and h-mode confinement...
TRANSCRIPT
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V.K. Gusev, N.N. Bakharev, A.A. Berezutskii, V.V. Bulanin, A.S. Bykov, S.E. Bender, F.V. Chernyshev,
I.N. Chugunov, V.V. Dyachenko, A.D. Iblyaminova, M.A. Irzak, A.A. Kavin, G.S. Kurskiev, S.A. Khitrov,
N.A. Khromov, V.A. Kornev, M.M. Larionov, K.M. Lobanov, A.D. Melnik, V.B. Minaev, A.B. Mineev,
M.I. Mironov, I.V. Miroshnikov, A.N. Novokhatsky, A.D. Ovsyannikov, A.A. Panasenkov, M.I. Patrov,
M.P. Petrov, Yu.V. Petrov, V.A. Rozhansky, V.V. Rozhdestvensky, A.N. Saveliev, N.V. Sakharov, P.B.
Shchegolev, O.N. Shcherbinin, I.Yu. Senichenkov, V.Yu. Sergeev, A.E. Shevelev, A.Yu. Stepanov,
S.Yu. Tolstyakov, V.I. Varfolomeev, A.V. Voronin, E.G. Zhilin, A.Yu. Yashin, F. Wagner, E.A. Kuznetsov,
V.A. Yagnov
• A.F. Ioffe Physico -Technical Institute, Russian Academy of Sciences, St. Petersburg, Russia
• Saint Petersburg State Polytechnical University, St. Petersburg, Russia
• D.V. Efremov Institutes of Electrophysical Apparatus, St. Petersburg, Russia
• Saint Petersburg State University, St. Petersburg, Russia
• IPT RRC “Kurchatov Institute”, Moscow, Russia
• Ioffe Fusion Technologies Ltd, St. Petersburg, Russia
• RLPAT Saint Petersburg State Polytechnical University, St. Petersburg, Russia; Max-Planck Institute,
Greifswald, Germany
• TRINITI, Troitsk, Moscow, Russia
Globus-M Results Toward Compact Spherical Tokamak
with enhanced Parameters Globus-M2
1 (24)
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R 0.36 m
a 0.24 m
R/a 1.5
Btor 0.4 T
Ipl < 0.36 MA
< 2.0
δ < 0.5
βtor <15 %
βN <6.0 %mT/МА
Tpulse <130 ms
NBI [E/P] 30 keV / 1 MW
ICRH [F/P] 10 MHz / 0.3 MW
Te [max] ~1 keV
Ti [max] ~0.8 keV
q95 [min] >2
Btor/R <1.5 T/m
<n> [max] <1.2 1020 m-3
Close fitting wall; RGT tiles; Plasma gun; LH CD system
Globus-M spherical tokamak demonstrated
practically all of the project objectives
Maximal T and n values were obtained in different regimes
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“B-max” regime providing:
BT(R=0.36) = 1 T for Δt =0.4 sec,
IP = 0.5 MA for 0.3 sec
“t-max” regime for noninductive
current drive experiments
providing:
BT(R=0.36) = 0.7 T for Δt = 0.8 sec
We propose the simplest way to improve plasma
parameters: both magnetic field and plasma current 2.5
increase retaining other machine parts unchanged.
The machine name is “Globus-M2” ST
3 (24)
M M2
M M2
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Objectives of Globus-M2 permit regime modeling for
Compact Fusion Neutron Source (CNFS)
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Globus-M confinement,
heating, fast particle physics
and edge plasma issues
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0 2 4 6 8
0
2
4
6
8 b) Deuterium
L-mode
H-mode
E(m
s)
<n>(1019
m-3
)
Saturation density limit
ns~0.65A1/2BT/qR
Ohmic L and H-mode confinement
Murakami-Hugill limit
ncrit~2BT/qR
Linear lifetime dependence is characteristic for small
size machines with domination of electron heat
transport, e.g. Alcator-A, ISX-B, etc 6 (24)
Globus-M H factor ~ 1
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NB injection is the major instrument for plasma auxiliary heating
in Globus-M
In spite of difficulties connected with a compact size of the
machine good ion heating efficiency during NB injection
observed at low density.
(2-4) 1019 m-3 i ~ i,neo
7 (24)
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• “Horizontal” lines approximate Fokker-Planck equation solution
with slowing down losses and allow for direct losses estimate
• Direct fast particle losses is the main mechanism deteriorating
NB plasma heating in Globus-M
• “Bump on tail” – demonstrates additional source of losses 8 (24)
Fast particle first orbit losses at various major radii
inward
outward
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NBI, 26 keV, 0.6 MW NBI, 25 keV, 0.6 MW
a b
ΔR= -1.5 cm
ΔR= 0 cm ΔR= +0.5 cm
Drastic decrease of fast particle losses can be achieved by total
magnetic field increase
Sawteeth are responsible for additional fast particle direct losses, producing
“bump on tail” distribution
9 (24)
D → D injection
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• Magnetic field 2.5 fold
increase make it possible 6
fold beam energy increase
without TAE spectrum
enrichment:
Vb/VA 1 on Globus-M
Vb/VA~ √Eb/B at ne=const
• Unlike TAE EPM is recorded
as multimode excitation
• No additional Fast particle
losses – evidence is
neutron flux measurement
• Expectations for Globus-M2
are favourable
TAE single n=1 mode excitation
10 (24)
H-NBI into D-plasma, E= 27 keV
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IR videocamera and Langmuir probes data:
SOL heat flux e-folding length, qMP 3-5 mm SOL
divertor plates width, qD 15-20 mm
Pmax/S 1.1 MW/m2 (OH LSN discharge)
qMP(1T) = 2aρ/R ~ 2a√Ti / RВpol ~ qMP(0.4T)
Prospects for edge plasma parameters is important issue for
the upgraded machine
B2 SOLPS
ASTRA
11 (24)
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ICRH prospects for 1 T in
Globus-M2
12 (24)
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If ВТ is increased from 0.4 to 1 T what will be benefits for ICRH
heating by FMS waves at fundamental harmonic range?
• Single pass resonance absorption of FMS
waves increasing due to λ decrease
• Ion-ion hybrid resonance absorption increasing
• High magnetic field improves fast ion
confinement and heating efficiency
BT 0.4Т 1 Т
1fci
for H+
6.1
МHz
15.2
МHz
13 (24)
ωH 2ωD
3ωD
2ωH
ωii
0 10 20 30 40 50 60
R (cm)
50
40
30
20
10
0
-10
-20
-30
-40
-50
Z (
cm
)
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0.4 0.6 0.8 1Bo, T
0
0.2
0.4
0.6
0.8
Rcoupl, O
hm
8 10 12 14frequency, MHz
Antenna-plasma coupling
resistance raise increases RF
power absorption efficiency with
magnetic field
-30 -20 -10 0 10 20 30 -30 -20 -10 0 10 20 30
4
3
2
1
0
4
3
2
1
0 a.u
.
a.u
.
ICR heating efficiency increases with magnetic field raise from
0.4 T to 1 T
Particle Fraction of power at
0.4 T
Fraction of power at
1.0 T
e- 0,641 0.46
p+ 0,260 0,38
d+ 0,099 0,16
CH = 10%
0.4 T 1 T
14 (24)
cm cm
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LH CD experiment in Globus-M and
expectations for Globus-M2
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Novel experimental arrangement was used in experiment with
plasma breakdown, current ramp-up and sustainment by LH waves
NEW antennae with
“toroidal” slow down:
Ntor ≈ (6 – 7)
Npol ≈ 1
OLD antennae with
“poloidal” slow down:
Ntor ≈ (1.0 – 15)
Npol ≈ (7 – 8)
16 (24)
Vessel walls were totally
protected by graphite
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0
5
10
15
20Plasma current (kA), shot #30529
0
1
2
3
4
5RF power (a.u.)
0
2
4
6
8Vertical field Bv (mT)
0
1
2
3D-alpha (a.u.)
0
1
2Line integrated density, R=0.24 m (10^18 m^-2)
0
1
2
3НXR (a.u.)
0
1
2Line integrated density, R=0.24 m (10^18 m^-2)
100 260140 180 220
Time (ms)
-1
0
1Mirnov signal (a.u.)
100 260140 180 220
Time (ms)
Line integrated density R=0.24 m (1018 m-2)
Line integrated density R=0.42 m (1018 m-2)
Contribution of the inductive
PF coil flux doesn’t exceed
20%
•Inductive flux conserved in the
plasma current surf = IpLext = 7,1 mWb
•Vertical field ramp-up flux
PF = Δtramp-up Usurf = 1,5 mWb
Total driven current comprises at least by 80% of noninductively
driven current by LH waves at 900 MHz and 60 kW RF power
launched
17 (24)
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Comparison with other experiments…
Globus-М, 2011-12, 0.4T MAST, 2009
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Time (ms)
LCFS
Noninductively driven current forms plasma column with closed
magnetic surfaces
Magnetic reconstruction by current filament method was used
19 (24)
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BT = 1 T
IP(total) = 0.5 MA; IP(LHCD) = 0.32 MA.
F=2.45 GHz; PLH = 0.5 MW 20 (24)
Preliminary ray tracing simulations of noninductive CD drive by
LH waves in Globus-M2
10-waveguides Grill may be oriented
both in poloidal and toroidal directions
0,0 0,2 0,4 0,6 0,8 1,00
1
2
3
4
5
Ne, T
e
Ne/10
19m
-3
Te, keV
0,0 0,2 0,4 0,6 0,8 1,00
1
2
3
4
5
J, M
A/m
2
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Globus-M2
parameter modeling
21 (24)
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Globus-M regimes provides basis for ASTRA code
modeling of Globus-M2 parameters
20 February 2012, RL-PAT seminar
0.150.932τ BI p
y,IPB98
EsmMGl
e
M2Gl
e / 3χ2.7
1χ 2
1.40.59 BI p
Valovic
E smMGl
e
M2Gl
e /3.1χ6.2
1χ 2
Electrons heat transport
Ions heat transport AN
i
NEOCL
ii += DAN
i
Particle transport – unchanged
IPB98(y,2)
Spherical tokamak scaling (M.Valovic et al, Nucl. Fusion, 2009, V49, p075016)
22 (24)
Instruments: ASTRA, NCLASS, NUBEAM codes
Reference case: Globus-M high density regime with e 8 m2/s
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IPB98(y,2) Valovic scaling
ASTRA simulation of ЕD = 30 keV, РNB = 1 MW NB injection into
Globus-M2 discharge demonstrates high value of temperature
at density ~ 0.7 1020m-3
23 (24)
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Conclusions
The analysis of Globus-M results on thermal and fast particle
confinement, RF heating and CD led to the conclusion on
magnetic field increase in Globus-M2
Upgrade allows for retaining the vacuum vessel and most part of
the diagnostics and heating systems.
Substantial improvement in parameters can be expected for
Globus-M2: density up to 1020 m-3 and temperatures in keV range
could be attained with high confidence.
The dimensionless parameter range for Globus-M2 allow
conditions characteristic for a compact fusion neutron source
experimental support.
24 (24)