1)
Integrated Predictive Modelling
at JET: Progress and Prospects
V. Parail1
With contributions from: P. Belo, G. Corrigan, W.
Fundamenski, W. Houlberg, G. Huysmans, X. Garbet, F.
Imbeaux, X. Litaudon. A. Loarte, J. Lonnroth, P. MonierGarbet, T. Onjun, G. Saibene, T. Tala, H. Wilson and
EFDA-JET collaborators
US-Japan JIFT Workshop on Theory-Based Modelling and Integrated Simulation of Burning Plasmas and
21COE Workshop on Plasma Theory, Kyoto, 2003/12/15-17
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Outlook
 What is integrated modelling?
 Why do we need it;
 Modelling codes, available at JET;
 Recent examples of integrated modelling of JET
plasmas:
Optimised shear plasma with ITBs;
ELMy H-mode, role of gas puffing;
Impurity accumulation and radiative collapse of ELMy H-mode;
Modelling of the Scrape Off Layer
 Problems and prospects.
US-Japan JIFT Workshop on Theory-Based Modelling and Integrated Simulation of Burning Plasmas and
21COE Workshop on Plasma Theory, Kyoto, 2003/12/15-17
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What is integrated modelling (1)
 Ecore
 ESOL
acore
FIRST WALL
 Traditionally, plasma in
tokamak is divided into two
regions: CORE and SOL;
 Indeed they have disparate
time and space scales:
a2

~ 1 sec;

q R

~ 100  sec;
VTi
~ 1 m ; SOL ~ 0.5 cm
 Plasma behaviour is
controlled by different
processes in CORE and SOL
CORE
SOL
US-Japan JIFT Workshop on Theory-Based Modelling and Integrated Simulation of Burning Plasmas and
21COE Workshop on Plasma Theory, Kyoto, 2003/12/15-17
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What is integrated modelling (2)
 Closer look reveals, however
that these regions influence
each other in many ways:
FIRST WALL
atomic physics penetrates into
plasma core with neutrals and
impurities;
profile stiffness makes core
plasma dependant on the
edge;
Edge transport barrier (which
serves to separate core from
SOL) is controlled by both;
MHD stability of ETB is
influenced by the SOL;
CORE
SOL
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21COE Workshop on Plasma Theory, Kyoto, 2003/12/15-17
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What is integrated modelling (3)
SAWTEETH
GRADIENT
REGION
ITB(s)
MHD
HEAT and
PARTICLE
FLUX
ETB
NEUTRALS
IMPURITIES
SOL
FIRST
WALL
PROFILE
STIFFNESS
STIFF
PROFILES
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Why do we need Integrated Modelling (1)
 Profile stiffness in
probably one of the
best examples of a
strong link between
core and edge;
 In case of a strong
stiffness:
Stiff
region
T
T (r )  T (a )  exp  dr 
T crit
r
a
confinement is controlled
by the edge only;
US-Japan JIFT Workshop on Theory-Based Modelling and Integrated Simulation of Burning Plasmas and
21COE Workshop on Plasma Theory, Kyoto, 2003/12/15-17
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Why do we need Integrated Modelling (2)
 Dynamical
interaction of
ITB(s) and
ETB:
US-Japan JIFT Workshop on Theory-Based Modelling and Integrated Simulation of Burning Plasmas and
21COE Workshop on Plasma Theory, Kyoto, 2003/12/15-17
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Why do we need Integrated Modelling (3)
 Dynamical interaction
of ITB(s) and ETB:
If enough power is
applied, ITB expands
toward the edge and
triggers L-H transition;
Emerging ETB and
subsequent strong ELMs
can erode ITB ,
sometimes leading to its
complete collapse;
US-Japan JIFT Workshop on Theory-Based Modelling and Integrated Simulation of Burning Plasmas and
21COE Workshop on Plasma Theory, Kyoto, 2003/12/15-17
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Why do we need Integrated Modelling (4)
 ELMy H-mode provides a classical example of the
interplay between core and edge transport as well as
between transport and MHD stability;
US-Japan JIFT Workshop on Theory-Based Modelling and Integrated Simulation of Burning Plasmas and
21COE Workshop on Plasma Theory, Kyoto, 2003/12/15-17
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Why do we need Integrated Modelling (5)
 Role of gas puffing
in ELM dynamics:
 Medium gas puffing
reduces ELM frequency
and amplitude without
significant degradation
in confinement;
 Strong gas puffing
leads to serious
degradation in
confinement and
transition to type-III
ELMs.
US-Japan JIFT Workshop on Theory-Based Modelling and Integrated Simulation of Burning Plasmas and
21COE Workshop on Plasma Theory, Kyoto, 2003/12/15-17
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Why do we need Integrated Modelling (6)
 Impurity accumulation
in the plasma core:
 The main gas puffing
plays a decisive role in
impurity accumulation
and thermal collapse
of plasma;
Main gas puff drops below critical level
US-Japan JIFT Workshop on Theory-Based Modelling and Integrated Simulation of Burning Plasmas and
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Modelling codes, available at JET (1)
 JET has a suite of transport codes, which are linked with
JET and ITER Profile Databases and are available to
remote users. This suite includes:
1.5D core transport code JETTO, which solves equations for
electron and ion temperature, two hydrogenic ion densities, cold
neutrals density and current density;
1D core transport code SANCO, which solves continuity
equations for all ionisation states of up to 2 impurity species.
The code is linked with JETTO;
2D SOL transport code EDGE2D/NIMBUS, which solves 2D
transport equations for electron and ion temperature, two main
hydrogenic ions and impurity densities as well as cold neutrals
distribution in the SOL;
US-Japan JIFT Workshop on Theory-Based Modelling and Integrated Simulation of Burning Plasmas and
21COE Workshop on Plasma Theory, Kyoto, 2003/12/15-17
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Modelling codes, available at JET (2)
A coupling between core (JETTO and SANCO) and edge
(EDGE2D/NIMBUS) codes: COCONUT;
We have a link (a unidirectional one, no feedback loop) between
transport code JETTO and linear MHD stability codes IDBALL,
HELENA, MISHKA and ELITE;
MISHKA and ELITE do a linear stability analysis of low to
medium-n ballooning and kink/peeling modes, including effect
of finite Larmor radius;
All our codes are available for all EFDA-JET collaborators,
including remote users;
The list of active remote users includes EU Associations, some
US Universities, Kurchatov Institute (Moscow), ITER Central
Team;
We provide training for new users (more than 30 users have
been trained so far)
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21COE Workshop on Plasma Theory, Kyoto, 2003/12/15-17
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Modelling codes, available at JET (3)
Present limitations in the modelling of core plasma:
 ICRH heating is not included into JETTO due to big
disparity in computation time (JETTO~1min CPU,
PION~1hour CPU);
 No feedback from MHD stability codes;
 Linear MHD stability analysis only
no reliable model
for ELM;
 Limited choice of theory-based transport models,
particularly concerning ITB;
US-Japan JIFT Workshop on Theory-Based Modelling and Integrated Simulation of Burning Plasmas and
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Modelling codes, available at JET (4)
Present limitations in the modelling of SOL plasma:
 Fluid approximation for SOL plasma (though flux limiters
and some drifts are introduced);
 Very limited package for plasma-wall interaction (such
as description of chemical sputtering, wall and target
plate recycling, kinetic model for sheath);
 Lack of theory-based models for anomalous transport in
the SOL both between and during ELMs
US-Japan JIFT Workshop on Theory-Based Modelling and Integrated Simulation of Burning Plasmas and
21COE Workshop on Plasma Theory, Kyoto, 2003/12/15-17
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Modelling codes, available at JET (4)
Problem of the multiplicity of transport and MHD stability
codes:
 Three 1.5D core transport codes are presently used at
JET (JETTO, ASTRA, CRONOS);
 These codes use different format for both input and
output parameters and different numerical schemes;
 They also use different graphic packages and file storing
facilities;
 Two 2D SOL codes (EDGE2D/NIMBUS and B2/EIRENA)
with the same problems, which were mentioned above;
US-Japan JIFT Workshop on Theory-Based Modelling and Integrated Simulation of Burning Plasmas and
21COE Workshop on Plasma Theory, Kyoto, 2003/12/15-17
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Recent examples of integrated modelling (1)
Optimised shear plasma with ITBs
 There can be more than one ITB in the same shot;
 ITB can change its radial position;
 ITB dynamically interacts with ETB;
 There is more than one mechanism of the ITB
formation
Strong shear flow;
negative magnetic shear;
Zero magnetic shear;
Low order rational magnetic surfaces;
Strong density gradient;
US-Japan JIFT Workshop on Theory-Based Modelling and Integrated Simulation of Burning Plasmas and
21COE Workshop on Plasma Theory, Kyoto, 2003/12/15-17
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Recent examples of integrated modelling (2)
 We manage to reproduce both
double-ITB structure and an
expansion of the outer ITB and
its interaction with the ETB;
 Bohm/gyroBohm empirical
modes has been used in the
simulation with:
 i   B   gB   ineo
B 
nTe 2 Te
q
nB
Te
 gB  Te
Te
B2
 (0.1  s  1.47)
r a

s
1s
US-Japan JIFT Workshop on Theory-Based Modelling and Integrated Simulation of Burning Plasmas and
21COE Workshop on Plasma Theory, Kyoto, 2003/12/15-17
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Recent examples of integrated modelling (3)
 It was not really an integrated modelling, we simulate
ETB by imposing a proper boundary conditions.
Modelling of ELMy H-mode, role of gas puffing.
To simulate H-mode plasma,
we assume that all transport
coefficients are reduced to the
level of ion neo-classical within
the barrier;
width of the ETB is prescribed
by the formula(s);
COCONUT is used so that SOL
physics is included (which
controls penetration of neutrals)
US-Japan JIFT Workshop on Theory-Based Modelling and Integrated Simulation of Burning Plasmas and
21COE Workshop on Plasma Theory, Kyoto, 2003/12/15-17
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Recent examples of integrated modelling (4)
 MHD stability reveals very interesting dependence of
edge stability on the level of gas puffing:
Low/no puffing
Medium puffing
Strong puffing
US-Japan JIFT Workshop on Theory-Based Modelling and Integrated Simulation of Burning Plasmas and
21COE Workshop on Plasma Theory, Kyoto, 2003/12/15-17
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Recent examples of integrated modelling (5)
 This integrated approach allows us to reproduce
experimentally observed transition from pure type-I
ELMs to a mixture of type-I-II and then to type-III with
an increase in the level of gas puffing;
US-Japan JIFT Workshop on Theory-Based Modelling and Integrated Simulation of Burning Plasmas and
21COE Workshop on Plasma Theory, Kyoto, 2003/12/15-17
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Recent examples of integrated modelling (6)
 Instead of using ad hoc assumption about ELM duration
and amplitude, Johnny Lonnroth starts using theorybased models for peeling and ballooning mode
evolution, coupled with transport equations:
cs   c    c 
cs
d
 C1
1   H 1    C2    0 
dt
R
Lp R      
0, x  0
H ( x)  
1, x  0
Te
cs 
mi
p
Lp 
p
C1  1
C2  0.1
 0  0.01
US-Japan JIFT Workshop on Theory-Based Modelling and Integrated Simulation of Burning Plasmas and
21COE Workshop on Plasma Theory, Kyoto, 2003/12/15-17
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Recent examples of integrated modelling (7)
 One of the most interesting outcome of this modelling that even
pure ballooning model reproduces discrete repetitive ELMs;
 Combination of peeling and ballooning reproduce “composite” ELM,
which is triggered by ballooning mode and then taken over by
J. Lonnroth, 2003
peeling
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21COE Workshop on Plasma Theory, Kyoto, 2003/12/15-17
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Recent examples of integrated modelling (8)
P. Snyder,
H. Wilson
US-Japan JIFT Workshop on Theory-Based Modelling and Integrated Simulation of Burning Plasmas and
21COE Workshop on Plasma Theory, Kyoto, 2003/12/15-17
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Recent examples of integrated modelling (9)
Impurity accumulation
and radiative
collapse of H-mode
 Our experience in
modelling of an
ELMy H-mode shows
that most of all gas
puffing influences
plasma parameters
in the SOL and
within the ETB;
Main gas puff drops below critical level
US-Japan JIFT Workshop on Theory-Based Modelling and Integrated Simulation of Burning Plasmas and
21COE Workshop on Plasma Theory, Kyoto, 2003/12/15-17
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Recent examples of integrated modelling (10)
 ETB is of a particular interest for our study since
anomalous transport there is suppressed between ELMs
and penetration of impurities is controlled by the neoclassical diffusion and pinch:
ineo

Zzneo
  1 dni
1 dnZ  H dTi 
 D K 



  ni dr Znz dr  Ti dr 
 here K is always positive and H is negative for the
banana regime and positive for the PS regime;
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21COE Workshop on Plasma Theory, Kyoto, 2003/12/15-17
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P. Belo, 2003
 Two sets of boundary conditions were used: the blue one
corresponds to a constant level of gas puff and the red
one- to its decrease
 There is a change in the radiated power and in ELM
behaviour at the time of the change in the boundary;
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21COE Workshop on Plasma Theory, Kyoto, 2003/12/15-17
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Modelling of the SOL (1)
 Modelling of the SOL raises an ultimate challenge
because of:
2D transport with disparate scales:L  i  0.5 cm ; LII  qR  10 m
This includes modelling of very short MHD phenomena like ELM
(with the duration ~100 sec);
Kinetic effects are important in longitudinal transport:
VTi
II 
 20 m (T i  100 eV , ni  1  10 19 m 3 )
 ii
Cold neutrals are 3D, as a rule;
Plasma-wall interaction involves processes, which are far from
being common in plasma physics (chemical sputtering,
blistering,…);
 Link with the core transport codes is crucial;
US-Japan JIFT Workshop on Theory-Based Modelling and Integrated Simulation of Burning Plasmas and
21COE Workshop on Plasma Theory, Kyoto, 2003/12/15-17
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Modelling of the SOL (2)
 Dynamics of the ELM penetration into SOL and it’s
expansion towards target is simulated with COCONUT
Ti
T=t0+2
Te
t=t0+
=4sec
t=t0 (before ELM)
J. Lonnroth, 2003
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Modelling of the SOL (3)
2,0
Accelerated Simulation of Charged
Particle Orbits in a Tokamak
1,5
1,0
• Guiding-centre orbit following
• 3-D Monte Carlo code
• All neo-classical effects (drifts)
• Ion-ion and ion-neutral collisions
• Self-consistent radial electric fields
• Real tokamak background data
• Parallelized using the MPI standard
0,0
-0,5
-1,0
-1,5

z (m)
0,5
Bx B
2,0
2,5
3,0
3,5
4,0
W. Fundamenski, 2003
R (m)
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Modelling of the SOL (4)
EFIT

GRID2D

OSM2 
EIRENE

ASCOT
W. Fundamenski, 2003
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21COE Workshop on Plasma Theory, Kyoto, 2003/12/15-17
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Integration of transport and MHD codes in JET (1)
The main motivation behind the Project is the
multiplicity of available codes in JET: 1.5D core transport
(ASTRA, CRONOS, JETTO), MHD stability codes (MISHKA,
ELITE, CHEESE, HELENA), 2D SOL codes (B2/EIRENA,
EDGE2D/NIMBUS) and some turbulence simulation codes
(KINEZERO, GS2, CUTIE);
The second drive comes from the recognition that we
are dealing with more and more complex phenomena,
which require integrated approach;
US-Japan JIFT Workshop on Theory-Based Modelling and Integrated Simulation of Burning Plasmas and
21COE Workshop on Plasma Theory, Kyoto, 2003/12/15-17
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Integration of transport and MHD codes in JET (2)
We decide that the first step towards unification and
integration would be to bring all codes under the same
shell so that similar codes can share the same
input/output files;
They will be all linked with JET and ITER Profile
databases and will all share the same input/output files;
This would allow users to use any code in a similar way
and to compare the codes in a very easy way;
Eventually I hope we will be able to choose the best
combination of codes (or modules) and to make this
option a preferential one on JET;
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Integration of transport and MHD codes in JET (3)
JAMS
ITER
PROFILE
DATABASE
JETDSP
PREJET
JETTO
MODEX
Users'
PPF
MHD
SANCO
JSP
JST
SST1
JSE
SSP1
CRONOS
CATALOGUE
MANAGER
ASTRA
KINEZERO
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21COE Workshop on Plasma Theory, Kyoto, 2003/12/15-17
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Integration of transport and MHD codes in JET (4)
We will try to modularise transport codes and share as
many components, as possible (and practical):
common impurity solver (SANCO);
equilibrium solver (and interface with MHD stability codes);
transport models;
Heating and current drive solvers (TRANSP Monte-Carlo
package for NBI, PION for ICRH);
postprocessing tools (synthetic diagnostics);
feedback control module;
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Problems and Prospects (1)
 The accuracy of our predictions is inversely proportional
to the complexity of plasma scenario (L-H-ITB);
 The main scientific challenge comes from the fact that
predictive modelling requires integration of processes
having different dimensionalities as well as problems of
disparate time or space scales;
 Predictive modelling requires specialists with a deep
knowledge of plasma theory, experiment and applied
mathematics, which are very difficult to bring up;
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21COE Workshop on Plasma Theory, Kyoto, 2003/12/15-17
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Problems and Prospects (2)
 Last years saw a very fast integration of theoretical,
experimental and modelling activities in plasma physics;
 ITER will be a logical next step in this integration since it
will require internationally approved integrated
modelling codes.
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21COE Workshop on Plasma Theory, Kyoto, 2003/12/15-17
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