Advances in the steady-state hybrid regime in DIII-D—a fully non-inductive, ELM-suppressed scenario for ITER

The hybrid regime with beta, collisionality, safety factor and plasma shape relevant to the ITER steady-state mission has been successfully integrated with ELM suppression by applying an odd parity n  =  3 resonant magnetic perturbation (RMP). Fully non-inductive hybrids in the DIII-D tokamak with high beta (〈β〉  ⩽  2.8%) and high confinement (H98y2  ⩽  1.4) in the ITER similar shape have achieved zero surface loop voltage for up to two current relaxation times using efficient central current drive from ECCD and NBCD. The n  =  3 RMP causes surprisingly little increase in thermal transport during ELM suppression. Poloidal magnetic flux pumping in hybrid plasmas maintains q above 1 without loss of current drive efficiency, except that experiments show that extremely peaked ECCD profiles can create sawteeth. During ECCD, Alfvén eigenmode (AE) activity is replaced by a more benign fishbone-like mode, reducing anomalous beam ion diffusion by a factor of 2. While the electron and ion thermal diffusivities substantially increase with higher ECCD power, the loss of confinement can be offset by the decreased fast ion transport resulting from AE suppression. Extrapolations from DIII-D along a dimensionless parameter scaling path as well as those using self-consistent theory-based modeling show that these ELM-suppressed, fully non-inductive hybrids can achieve the Qfus  =  5 ITER steady-state mission.

[1]  G. Staebler,et al.  Predicting rotation for ITER via studies of intrinsic torque and momentum transport in DIII-D , 2017 .

[2]  J. S. deGrassie,et al.  Dependence of intrinsic torque and momentum confinement on normalized gyroradius and collisionality in the DIII-D tokamak , 2017 .

[3]  W. Heidbrink,et al.  Fast ion profile stiffness due to the resonance overlap of multiple Alfvén eigenmodes , 2016 .

[4]  R. White,et al.  Observation of Critical-Gradient Behavior in Alfvén-Eigenmode-Induced Fast-Ion Transport. , 2016, Physical review letters.

[5]  Nathaniel Ferraro,et al.  Self-Organized Stationary States of Tokamaks. , 2015, Physical review letters.

[6]  C. C. Petty,et al.  The high-βN hybrid scenario for ITER and FNSF steady-state missionsa) , 2015 .

[7]  G. Staebler,et al.  Impurity confinement and transport in high confinement regimes without edge localized modes on DIII-Da) , 2015 .

[8]  A. Leonard.  Edge-localized-modes in tokamaksa) , 2014 .

[9]  L. L. Lao,et al.  Physics Basis of a Fusion Development Facility Utilizing the Tokamak Approach , 2010 .

[10]  T. C. Luce,et al.  Realizing Steady State Tokamak Operation for Fusion Energy , 2009 .

[11]  M. Wade,et al.  Magnetic-flux pumping in high-performance, stationary plasmas with tearing modes. , 2009, Physical review letters.

[12]  T. Petrie,et al.  Influence of toroidal rotation on transport and stability in hybrid scenario plasmas in DIII-D , 2008 .

[13]  R. E. Waltz,et al.  The first transport code simulations using the trapped gyro-Landau-fluid model , 2008 .

[14]  J. S. deGrassie,et al.  RMP ELM suppression in DIII-D plasmas with ITER similar shapes and collisionalities , 2008 .

[15]  Maxim Umansky,et al.  Stability and dynamics of the edge pedestal in the low collisionality regime: physics mechanisms for steady-state ELM-free operation , 2007 .

[16]  T. Luce,et al.  Evidence for anomalous effects on the current evolution in the tokamak hybrid operating scenarios , 2007 .

[17]  E. Joffrin,et al.  Chapter 6: Steady state operation , 2007 .

[18]  C. Hegna,et al.  Effect of neoclassical toroidal viscosity on error-field penetration thresholds in tokamak plasmas. , 2006, Physical review letters.

[19]  C. M. Greenfield,et al.  Development, physics basis and performance projections for hybrid scenario operation in ITER on DIII-D , 2005 .

[20]  R. Budny,et al.  Transport modelling and gyrokinetic analysis of advanced high performance discharges , 2005 .

[21]  G. Bateman,et al.  The tokamak Monte Carlo fast ion module NUBEAM in the National Transport Code Collaboration library , 2004 .

[22]  M. R. Wade,et al.  High performance stationary discharges in the DIII-D tokamak , 2004 .

[23]  L. Lao,et al.  ELMs and constraints on the H-mode pedestal: peeling–ballooning stability calculation and comparison with experiment , 2004 .

[24]  P. Snyder,et al.  Ideal magnetohydrodynamic constraints on the pedestal temperature in tokamaks , 2003 .

[25]  L. Lao,et al.  Edge localized modes and the pedestal: A model based on coupled peeling–ballooning modes , 2002 .

[26]  F. Milani,et al.  Recent Progress on JET Towards the ITER Reference Mode of Operation at High Density. Invited Paper , 2001 .

[27]  P. Barabaschi,et al.  ITER: opportunity of burning plasma studies , 2001 .

[28]  A. Boozer.  Error field amplification and rotation damping in tokamak plasmas. , 2001, Physical review letters.

[29]  L. L. Lao,et al.  Progress toward long-pulse high-performance Advanced Tokamak discharges on the DIII-D tokamak , 2001 .

[30]  R. Aymar,et al.  ITER-FEAT - the future international burning plasma experiment - present status , 2000 .

[31]  L. L. Lao,et al.  LONG-PULSE, HIGH-PERFORMANCE DISCHARGES IN THE DIII-D TOKAMAK , 2000 .

[32]  Current Drive.  Chapter 6: Plasma auxiliary heating and current drive , 1999 .

[33]  G. Giruzzi,et al.  GENERATION OF LOCALIZED NONINDUCTIVE CURRENT BY ELECTRON CYCLOTRON WAVES ON THE DIII-D TOKAMAK , 1999 .

[34]  A. Pletzer,et al.  Theory of perturbed equilibria for solving the Grad–Shafranov equation , 1999 .

[35]  M. R. Wade,et al.  Dependence of Heat and Particle Transport on the Ratio of the Ion and Electron Temperatures , 1999 .

[36]  O. Sauter,et al.  Neoclassical conductivity and bootstrap current formulas for general axisymmetric equilibria and arbitrary collisionality regime , 1999 .

[37]  M. Wade,et al.  Measurement and verification of zeff radial profiles using charge exchange recombination spectroscopy on DIII-D , 1998 .

[38]  Lao,et al.  Determination of the noninductive current profile in tokamak plasmas. , 1994, Physical review letters.

[39]  L. Lao,et al.  Polarimetry of motional Stark effect and determination of current profiles in DIII-D (invited) , 1992 .

[40]  G. L. Campbell,et al.  Design and operation of the multipulse Thomson scattering diagnostic on DIII‐D (invited) , 1992 .

[41]  K. Burrell,et al.  High spatial and temporal resolution visible spectroscopy of the plasma edge in DIII‐D , 1990 .

[42]  L. L. Lao,et al.  Equilibrium analysis of current profiles in tokamaks , 1990 .

[43]  K. Matsuda,et al.  Ray tracing study of the electron cyclotron current drive in DIII-D using 60 GHz , 1989 .

[44]  S. Wolfe,et al.  A new look at density limits in tokamaks , 1988 .

[45]  R. Cohen.  Effect of trapped electrons on current drive , 1987 .

[46]  L. Lao,et al.  Reconstruction of current profile parameters and plasma shapes in tokamaks , 1985 .

[47]  R. Goldston,et al.  New techniques for calculating heat and particle source rates due to neutral beam injection in axisymmetric tokamaks , 1981 .

[48]  F. Hinton,et al.  Theory of plasma transport in toroidal confinement systems , 1976 .

[49]  C. Holcomb,et al.  Impact of ideal MHD stability limits on high-beta hybrid operation , 2016 .

[50]  J. Kinsey,et al.  High-beta, steady-state hybrid scenario on DIII-D , 2015 .

[51]  T. Luce,et al.  Spatiotemporal changes in the pressure-driven current densities on DIII-D due to magnetic islands , 2011 .