OVERVIEW OF ITER PHYSICS

1
ITER
OVERVIEW OF ITER PHYSICS
V. Mukhovatov1, M. Shimada1, A.E. Costley1, Y.
Gribov1, G. Federici2,A.S. Kukushkin2, A.
Polevoi1, V.D. Pustovitov3, Y. Shimomura1, T.
Sugie1, M. Sugihara1, G. Vayakis1 1
International Team, ITER Naka Joint Work Site,
Naka, Ibaraki, Japan 2 International Team, ITER
Garching Joint Work Site, Garching, Germany 3
Nuclear Fusion Institute, RRC Kurchatov
Institute, Moscow, Russia
V. Mukhovatov et al., 30th EPS Conf. on Control.
Fusion and Plasma Phys., July 7-11, 2003, St
Petersburg, Russia
2
Contents

• Introduction
• ELMy H-mode
• Operational limits
• Confinement
• Instabilities
• Improved H-mode
• Internal Transport Barriers
• Formation
• Performance
• Control
• Summary

V. Mukhovatov et al., 30th EPS Conf. on Control.
Fusion and Plasma Phys., July 7-11, 2003, St
Petersburg, Russi
3
Introduction

• Predictive methodologies for tokamak Burning
  Plasma Experiment (BPX) have been summarized in
  the ITER Physics Basis (IPB) published in 1999
  Nucl. Fusion 39 (1999) 2137-2638.
• In recent years, significant progress has been
  achieved in many areas of tokamak physics
• New achievements have had significant impact on
  new ITER design (stronger shaping, methods to
  suppress NTMs and RWMs)
• This talk reviews the ITER physics basis taking
  account of the recent progress in tokamak studies

V. Mukhovatov et al., 30th EPS Conf. on Control.
Fusion and Plasma Phys., July 7-11, 2003, St
Petersburg, Russia
4
Major ITER-Relevant Confinement Modes

• H-mode (High Confinement Mode) associated with
  formation of edge transport barrier (ETB)
• Reference mode for ITER inductive high-Q
  operation
• Improved H-mode
• Candidate mode for inductive and/or hybrid ITER
  operation
• Advanced Tokamak (AT) mode associated with
  formation of Internal Transport Barrier (ITB)
• Candidate mode for steady-state ITER operation

V. Mukhovatov et al., 30th EPS Conf. on Control.
Fusion and Plasma Phys., July 7-11, 2003, St
Petersburg, Russia
5
Physics Rules for Selection of ITER Design
Parameters

• Q 10 Q 5Pa/Paux
• ELMy H-mode reference operation mode
• ITERH-98P(y,2) scaling for energy confinement
  time
• Safety factor q95 2.5 q95 µ (5B/I)(ka2/R)
• Electron density ne nG nG I/(pa2), Greenwald
  density
• Normalized beta bN 2.5 bN b()(aB/I)
• Strong plasma shaping ksep 1.85, dsep 0.48
• Heating power P 1.3 PL-H P Pa Paux- Prad
• PL-H is H-mode power thresh.

V. Mukhovatov et al., 30th EPS Conf. on Control.
Fusion and Plasma Phys., July 7-11, 2003, St
Petersburg, Russia
6
ELMy H-MODE
7
ELMy H-mode

• ELMy H-mode H-mode with bursts of Edge Localized
  Modes (ELMs)
• Reference ITER mode for inductive high-Q
  operation
• Robust mode observed in all tokamaks under wide
  variety of conditions at heating power above the
  threshold, PgtPL-H
• Good prospects for long-pulse operation
• gt20 years of studies
• Rich experimental database
• High confidence that ELMy H-mode will be obtained
  in ITER

V. Mukhovatov et al., 30th EPS Conf. on Control.
Fusion and Plasma Phys., July 7-11, 2003, St
Petersburg, Russia
8
Energy Confinement Projections for ELMy H-mode in
ITER

• Three approaches (discussed in details in IPB)
  predict compatible results for ITER reference
  high Q scenario
• Transport models based on empirical scalings for
  the energy confinement time
• Physics-based transport models
• Dimensionless analysis

V. Mukhovatov et al., 30th EPS Conf. on Control.
Fusion and Plasma Phys., July 7-11, 2003, St
Petersburg, Russia
9
ITER Reference Scalings
ITERH-98P(y.2) confinement scaling ITER tE
3.66s 14 2.78, 4.83s 95 nonlinear
interval estimate
H-mode power threshold scaling ITER PL-H 49 MW
28.4, 84.1MW 95 interval estimate
O.Kardaun, Nucl. Fusion 42 (2002) 841
J A Snipes et al PPCF 42 (2000) A299
V. Mukhovatov et al., 30th EPS Conf. on Control.
Fusion and Plasma Phys., July 7-11, 2003, St
Petersburg, Russia
10
Effect of Plasma Dilution with Helium

• ITER performance depends on plasma dilution with
  He
• B2/Eirene code
• Helium content in ITER plasma reduces due to
  Helium atom elastic collisions with D/T ions
• Reduction of He content improves ITER performance

1/2D ITINT1.SAS code with Psep PL-H O.J.W.F.
Kardaun NF 42 (2002) 841
V. Mukhovatov et al., 30th EPS Conf. on Control.
Fusion and Plasma Phys., July 7-11, 2003, St
Petersburg, Russia
11
Theory Based Transport Models

• WEILAND, MMM, GLF23 and IFS/PPPL transport
  models
• Transport driven by drift wave turbulence
• Detailed treatment is somewhat different
• Boundary conditions taken from experiments or
  from empirical or semi-empirical scalings
• Reasonable agreement with experimental data for
  plasma core

V. Mukhovatov et al., 30th EPS Conf. on Control.
Fusion and Plasma Phys., July 7-11, 2003, St
Petersburg, Russia
12
ITER Predictions by Physics Based Models
Pedestal scalings (a) J G Cordey, et al 19th
FEC Lyon (b) J G Cordey, et al 19th FEC,
Lyon (c) M Sugihara, et al NF 40 (2002)
1743 (d) A H Kritz, et al 29th EPS D-5.001 (e)
M Sugihara, et al submitted to PPCF (g) K S
Shaing T H Osborne et al 19th FEC, Lyon
V. Mukhovatov et al., 30th EPS Conf. on Control.
Fusion and Plasma Phys., July 7-11, 2003, St
Petersburg, Russia
13
ITER Predictions by Physics Based Models
Predictions for ITER by different models at the
same input parameters (G. Pereverzev et al. 29th
EPS 2002 P-1072)
V. Mukhovatov et al., 30th EPS Conf. on Control.
Fusion and Plasma Phys., July 7-11, 2003, St
Petersburg, Russia
14
Edge Pedestal in ELMy H-mode
Two-term confinement scalings for thermal energy
W Wcore Wped Edge temperature
gradient limited by thermal conduction ITER
Wped 174 MW Tped 5.2
keV Edge gradient limited by ELMs (MHD
limit) ITER Wped 98 MW
Tped 3.0 keV
J.G.Cordey et al IAEA Lyon Conf. 2002
M Sugihara et al , submitted tp PPCF
2003
V. Mukhovatov et al., 30th EPS Conf. on Control.
Fusion and Plasma Phys., July 7-11, 2003, St
Petersburg, Russia
15
Non-Dimensional Confinement Scalings

• GyroBohm like scalings have been found in
  experiments with ELMy H-mode
• BtE µ (r)-3.15 b 0.03 (n)-0.42 in DIII-D
• BtE µ (r)-2.7 b -0.05 ( n)-0.27 in JET
  (r ri/a)
• JET DT discharge with all dimensionless
  parameters, b, n, q, R/a, k, d, etc,
  except r, the same as ITER
• JET 42983 r 4.25 10-3
• JET-like ITER r 1.88 10-3
• gt Q 6 - 13

V. Mukhovatov et al., 30th EPS Conf. on Control.
Fusion and Plasma Phys., July 7-11, 2003, St
Petersburg, Russia
16
High Performance H-Modes at High Density
Demonstrated

• One of the major achievements in recent tokamak
  experiments was demonstration of good confinement
  in H-mode at high plasma density required for
  ITER, i.e.
• H98(y,2) 1 at n 0.85 nG
• There are several ways to improve confinement at
  high density
• Increase in plasma triangularity gentle gas fuff
• Impurity seeding
• High field side pellet fueling

V. Mukhovatov et al., 30th EPS Conf. on Control.
Fusion and Plasma Phys., July 7-11, 2003, St
Petersburg, Russia
17
Good Confinement at High Density
Energy confinement reduces with density but
improves with plasma triangularity d or shaping
parameter q95/qcyl H(y,2)corr 0.46 1.35
ln(q95/qcyl) - 0.17 n/nG 0.38(n/nped -1) ITER
H(y,2)corr0.91 at n/nped1 H(y,2)corr1.05 at
n/nped1.3
JET
ITER
V. Mukhovatov et al., 30th EPS Conf. on Control.
Fusion and Plasma Phys., July 7-11, 2003, St
Petersburg, Russia
18
Power and Particle Control in ITER

• B2/Eirene code steady state divertor power loads
  are within the proven limits
• He density at the separatrix reduces by 3-5 times
  due to elastic collisions of He atoms with D/T
  ions
• A S
  Kukushkin, H D Pacher PPCF 44 (2002) 943

V. Mukhovatov et al., 30th EPS Conf. on Control.
Fusion and Plasma Phys., July 7-11, 2003, St
Petersburg, Russia
19
Major Instabilities in ELMy H-mode

• Sawteeth
• Edge localized modes (ELMs)
• Neoclassical tearing modes (NTMs)
• Alfven instabilities
• Disruptions

V. Mukhovatov et al., 30th EPS Conf. on Control.
Fusion and Plasma Phys., July 7-11, 2003, St
Petersburg, Russia
20
EDGE LOCALIZED MODES (ELMs)
21
H-mode Regimes with Smaller ELMs

• Expected energy fluxes on the ITER divertor
  associated with ELMs are close to being marginal
  for an acceptable divertor target life time
• There are alternative high confinement modes with
  small ELMs found at q95 gt 3.6-4 and high
  triangularity
• H-mode with grassy or minute ELMs in DIII-D
  and JT-60U
• Enhanced Da (EDA) mode in Alcator C-Mod with
  quasi-coherent density fluctuations
• Advanced H-mode with Type II ELMs in ASDEX-U
• Impurity seeded H-mode in JET with reduced Type I
  ELMs
• High density H-mode with rear small ELMs in JET
• Quiescent Double Barrier (QDB) H-mode in DIII-D
• ELM mitigation with frequent pellet injection is
  promising

V. Mukhovatov et al., 30th EPS Conf. on Control.
Fusion and Plasma Phys., July 7-11, 2003, St
Petersburg, Russia
22
ELM Mitigation Using Pellet Injection
4Hz pellet injection in ITER can reduce the
energy loss per ELM to acceptable level
(A Polevoi et al 19 FEC Lyon 2002)
ELM induced energy loss is reduced in ASDEX
Upgrade at sufficiently high frequency of pellet
injection (P Lang, 2002)
V. Mukhovatov et al., 30th EPS Conf. on Control.
Fusion and Plasma Phys., July 7-11, 2003, St
Petersburg, Russia
23
NEOCLASSICAL TEARING MODES (NTMs)
24
Neoclassical Tearing Modes (NTMs)

• Neoclassical tearing modes (NTMs) are induced by
  reduction of bootstrap current inside magnetic
  islands
• Deteriorate confinement and determine the lowest
  beta limit
• NTMs methastable seed islands are required
• NTM can be stabilized with localized current
  drive within magnetic island

V. Mukhovatov et al., 30th EPS Conf. on Control.
Fusion and Plasma Phys., July 7-11, 2003, St
Petersburg, Russia
25
Neoclassical Tearing Modes (NTMs)

• Complete 3/2 NTM suppression demonstrated (AUG,
  DIII-D, JT-60U) with localized ECCD
• Complete 2/1 NTM suppression demonstrated
  (DIII-D)
• Real-time ECCD position control demonstrated
  (DIII-D)

V. Mukhovatov et al., 30th EPS Conf. on Control.
Fusion and Plasma Phys., July 7-11, 2003, St
Petersburg, Russia
26
Suppression of NTMs in ITER

• Extrapolation to ITER PECCD (30 15) MW
  (G Giruzzi and H Zohm, ITPA
  MHD Meering, Naka, Feb 2002)
• Early injection would enable NTM stabilization
  with PECCDlt 20 MW
• ITER design PECCD 20 MW

m/n 2/1
A Zvonkov ,
2000
V. Mukhovatov et al., 30th EPS Conf. on Control.
Fusion and Plasma Phys., July 7-11, 2003, St
Petersburg, Russia
27
DISRUPTION MITIGATION
28
Disruption Mitigation

• Mechanical loads during disruptions are within
  the design limits (confirmed by DINA) (M.Sugihara
  et al, this Conference)
• Promising disruption mitigation technique
• DIII-D High-pressure noble gas jet injection
• (D G Whyte FEC 2002, Lyon)
• V. Riccardo, this Session

V. Mukhovatov et al., 30th EPS Conf. on Control.
Fusion and Plasma Phys., July 7-11, 2003, St
Petersburg, Russia
29
Noble Gas Jet Injection in ITER

• Preliminary modeling the technique is feasible
  for ITER
• Operation space limited by melting/ablating the
  first wall

2 0 1 0 8
0
(1021 m-3)
ITER-98
0 1 2 3
4 t (ms)
D G Whyte 19th FEC 2002, Lyon
V. Mukhovatov et al., 30th EPS Conf. on Control.
Fusion and Plasma Phys., July 7-11, 2003, St
Petersburg, Russia
30
IMPROVED H-MODE
31
Q10 Scenario at Reduced Current

• Regime with lower current (higher q95) would be
  beneficial to reduce disruption forces and for
  access to benign (Type II) ELM regime but
  requires improved confinement
• Recently ASDEX Upgrade, DIII-D and JET
  demonstrated a possibility to obtain plasmas with
  improved confinement,
• H98(y,2) 1.2-1.4, at q95
  3.6-4.2
• (correspond to I 12.5 - 10.5 MA in
  ITER)

V. Mukhovatov et al., 30th EPS Conf. on Control.
Fusion and Plasma Phys., July 7-11, 2003, St
Petersburg, Russia
32
Advanced H-mode with Type II ELMs
No sawteeth q(0) 1 bN 3.5 q95 3.6
H98(y,2) 1.3 n nG Dt 40 tE Low divertor
heat load (Type II ELMs)
ASDEX Upgrade
V. Mukhovatov et al., 30th EPS Conf. on Control.
Fusion and Plasma Phys., July 7-11, 2003, St
Petersburg, Russia
33
INTERNAL TRANSPORT BARRIERS (ITBs)
34
Steady-State Q5 Operation in ITER

• Requirements
• H98P(y.2) gt 1.3-1.5
• High beta bN gt 2.6
• High bootstrap current fraction,fBS 50
• Advanced Tokamak Mode
• Regimes with Internal Transport Barriers (ITBs)
• Weak or negative magnetic shear
• Resistive wall mode stabilization

V. Mukhovatov et al., 30th EPS Conf. on Control.
Fusion and Plasma Phys., July 7-11, 2003, St
Petersburg, Russia
35
ITB Power Threshold

• The target plasmas with weak or negative magnetic
  shear require lower heating power for ITB
  formation G T Hoang et al, 29th EPS Conf. 2002

• The rarefaction of resonance surfaces at low/zero
  magnetic shear helps ITB formation while the
  barrier width is probably controlled by the ExB
  shear
• JET and ASDEX-U indicate importance of rational
  q in the vicinity of zero magnetic shear
• E Joffrin et al 19th FEC
  Lyon 2002

V. Mukhovatov et al., 30th EPS Conf. on Control.
Fusion and Plasma Phys., July 7-11, 2003, St
Petersburg, Russia
36
Real-Time Control of ITBs in JET
V. Mukhovatov et al., 30th EPS Conf. on Control.
Fusion and Plasma Phys., July 7-11, 2003, St
Petersburg, Russia 50
37
JT-60U ITB and Current Hole
Transiently I2.6 MA, q953.3, tE0.89 s,
Qeq1.2 HH98y,21.5, bN 1.6 ne(0) 1020 m-3

• Current hole and ITB at strong negative shear
  has been sustained for 5 s in JT60-U at I 1.35
  MA, q955.2, HH98y,21.5, bN 1.7
• T(r) and n(r) are flat inside the current hole

V. Mukhovatov et al., 30th EPS Conf. on Control.
Fusion and Plasma Phys., July 7-11, 2003, St
Petersburg, Russia
38
RESISTIVE WALL MODES (RWMs)
39
Suppression of Resistive Wall Modes

• DIII-D Dynamic error field corrections by
  feedback control allows rotational stabilization
  of RWMs bNbN(ideal wall) 2bN(no-wall limit) at
  wrot gt 2 wAlfven
• DIII-D Negative central shear plasma
  fBS 65, fnon-ind 85, bT
  4 (E J Strait et all 19th FEC Lyon 2002)

V. Mukhovatov et al., 30th EPS Conf. on Control.
Fusion and Plasma Phys., July 7-11, 2003, St
Petersburg, Russia
40
Suppression of RWM in ITER

• Extrapolation to ITER
• Model developed taking account realistic vessel
  and coil geometry and plasma rotation (A
  Bondeson, next report)
• Side correction coils will be used for RWM
  stabilization (similar to that in DIII-D)

Cb 0.8 is achievable
V. Mukhovatov et al., 30th EPS Conf. on Control.
Fusion and Plasma Phys., July 7-11, 2003, St
Petersburg, Russia
41
Requirements for Power Reactor

• Analysis study suggests that it is possible to
  achieve most normalized plasma parameters in ITER
  to enable projection to fusion power reactor,
  i.e. demonstration of Pfus0.7GW and simulation
  of Pfus 1 GW
• 
  (M.Shimada, this Conference, Thursday 10 July)

V. Mukhovatov et al., 30th EPS Conf. on Control.
Fusion and Plasma Phys., July 7-11, 2003, St
Petersburg, Russia
42
Requirements for Plasma Measurements

• The requirements for plasma and first wall
  measurements on ITER are well developed and many
  diagnostic systems have been designed to an
  advanced level
• Solutions to many of the difficult implementation
  issues that arise on a DT machine have been
  found, and design and RD is in progress on
  outstanding issues
• It is believed that the measurements necessary
  for the machine protection and basic plasma
  control can be made at the required level of
  accuracy etc, and also many of those now
  identified as necessary to support the advanced
  operation
• There are several papers on ITER diagnostics
  presented in the diagnostic sessions on Thursday
  and Friday afternoons including an overview oral
  by A Costley on long pulse issues in ITER
  diagnostics

V. Mukhovatov et al., 30th EPS Conf. on Control.
Fusion and Plasma Phys., July 7-11, 2003, St
Petersburg, Russia
43
Summary - I

• The reference plasma parameters required for
  inductive high-Q operation in ITER (bN 1.8, q95
  3, H98(y,2) 1, n/nG 0.85) are demonstrated
  on present machines
• The feasibility of achieving Q 10 in H-mode
  predicted by transport model based on empirical
  confinement scaling is confirmed by dimensionless
  analysis and theory-based transport modeling
• Active control of NTMs and mitigation of ELMs and
  disruptions may be necessary. Relevant control
  and mitigation techniques suggested and tested.
  Extrapolation to ITER needs further work

V. Mukhovatov et al., 30th EPS Conf. on Control.
Fusion and Plasma Phys., July 7-11, 2003, St
Petersburg, Russia
44
Summary - II

• Requirements for ITER steady-state Q5 operation
  (bN gt 2.6, H98(y,2) gt 1.3, fBS gt 0.5, n
  nG) developed. Normalized parameters
  demonstrated in experiments
• More sophisticated control schemes (i.e. current
  and pressure profiles) will be necessary for
  steady state operation. Such schemes are under
  development
• Achievement of more demanding normalized
  parameters (bN gt 3.6) and high fusion power,
  700MW, necessary to facilitate extrapolation of
  plasma performance to fusion power reactor is
  under study and looks possible

V. Mukhovatov et al., 30th EPS Conf. on Control.
Fusion and Plasma Phys., July 7-11, 2003, St
Petersburg, Russia
45
LIST OF ITER IT REPORTS AT THIS CONFERENCE V.
Mukhovatov Overview of ITER Physics (Wednesday,
July 9) I-3.3A M. Shimada High Performance
Operation in ITER (Thursday, July 10) P-3.137 M.
Sugihara Examination on Plasma Behaviors during
Disruptions on Existing Tokamaks and Their
Extrapolations to ITER (Tuesday, July 8)
P-2.139 A.S. Kukushkin Effect of Carbon
Redeposition on the Divertor Performance in ITER
(Thursday, July 10) P-3.195 A. Costley Long
Pulse Operation in ITER Issues for Diagnostics
(Friday, July 11) O-4.1D K. Itami
Study of Multiplexing Thermography for ITER
Divertor Targets (Friday, July 11) P-4.62 T.
Kondoh Toroidal Interferometer/Polarimeter
Density Measurement System for Long Pulse
Operation on ITER (Friday, July 11) P-4.64 T.
Kondoh Prospects for Alpha-Particle Diagnostics
by CO2 Laser Collective Thomson Scattering on
ITER (Friday, July 11) P-4.65 T. Sugie
Spectroscopic Measurement System for ITER
Divertor Plasma Divertor Impurity Monitor
(Friday, July 11) P-4.63 C. Walker Erosion and
Redeposition on Diagnostic Mirrors for ITER
First Mirror Test at JET and TEXTOR (Friday,
July 11) P-4.59 C.I. Walker ITER Generic
Diagnostic Components and Systems for Integration
(Friday, July 11) P-4.61