## This content will become publicly available on December 2, 2020

# Prediction of Alfvén eigenmode energetic particle transport in ITER scenarios with a critical gradient model

## Abstract

A reduced 1D, local, critical-gradient model of energetic particle (EP) transport by Alfvén eigenmodes (AEs)—the TGLF-EP+Alpha model—is applied to a much-studied ITER base case and variations with lower plasma current and lower current penetration. The TGLF-EP+Alpha model is a greatly reduced and computationally inexpensive model of EP transport. Such a reduced critical gradient model, while inapplicable to transport driven by strongly nonlinear or non-local abrupt events, is a valuable tool for scoping studies needed in scenario optimization for ITER and beyond. Furthermore, it relies on the assumption of critical-gradient AE transport with the critical EP density gradient determined by linear AE stability calculations in the TGLF gyro-Landau fluid code automated with the parallel-processed TGLF-EP wrapper. EP transport is treated with simultaneous drive of AEs by fusion-born alpha particles and fast ions born from a 1 MeV neutral beam injection (NBI) heating. The effect of simultaneous drive creates about 50% increased particle transport in both EP channels. High magnetic safety factor q and low shear $$\hat{s}$$ are generally destabilizing to AEs, but low shear tends to be more important. A tailored q-profile, steady-staterelevant scenario can reduce AE-induced EP redistribution by better than 25% over the ITER base case despite having half the total current.

- Authors:

- Univ. of California, San Diego, CA (United States). Dept. of Physics
- General Atomics, San Diego, CA (United States)

- Publication Date:

- Research Org.:
- General Atomics, San Diego, CA (United States)

- Sponsoring Org.:
- USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)

- OSTI Identifier:
- 1597824

- Grant/Contract Number:
- [SC0018108; FG02-95ER54309]

- Resource Type:
- Accepted Manuscript

- Journal Name:
- Nuclear Fusion

- Additional Journal Information:
- [ Journal Volume: 60; Journal Issue: 1]; Journal ID: ISSN 0029-5515

- Publisher:
- IOP Science

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Alfvén eigenmodes; energetic particles; ITER; transport

### Citation Formats

```
Bass, E. M., and Waltz, R. E. Prediction of Alfvén eigenmode energetic particle transport in ITER scenarios with a critical gradient model. United States: N. p., 2019.
Web. doi:10.1088/1741-4326/ab54fb.
```

```
Bass, E. M., & Waltz, R. E. Prediction of Alfvén eigenmode energetic particle transport in ITER scenarios with a critical gradient model. United States. doi:10.1088/1741-4326/ab54fb.
```

```
Bass, E. M., and Waltz, R. E. Mon .
"Prediction of Alfvén eigenmode energetic particle transport in ITER scenarios with a critical gradient model". United States. doi:10.1088/1741-4326/ab54fb.
```

```
@article{osti_1597824,
```

title = {Prediction of Alfvén eigenmode energetic particle transport in ITER scenarios with a critical gradient model},

author = {Bass, E. M. and Waltz, R. E.},

abstractNote = {A reduced 1D, local, critical-gradient model of energetic particle (EP) transport by Alfvén eigenmodes (AEs)—the TGLF-EP+Alpha model—is applied to a much-studied ITER base case and variations with lower plasma current and lower current penetration. The TGLF-EP+Alpha model is a greatly reduced and computationally inexpensive model of EP transport. Such a reduced critical gradient model, while inapplicable to transport driven by strongly nonlinear or non-local abrupt events, is a valuable tool for scoping studies needed in scenario optimization for ITER and beyond. Furthermore, it relies on the assumption of critical-gradient AE transport with the critical EP density gradient determined by linear AE stability calculations in the TGLF gyro-Landau fluid code automated with the parallel-processed TGLF-EP wrapper. EP transport is treated with simultaneous drive of AEs by fusion-born alpha particles and fast ions born from a 1 MeV neutral beam injection (NBI) heating. The effect of simultaneous drive creates about 50% increased particle transport in both EP channels. High magnetic safety factor q and low shear $\hat{s}$ are generally destabilizing to AEs, but low shear tends to be more important. A tailored q-profile, steady-staterelevant scenario can reduce AE-induced EP redistribution by better than 25% over the ITER base case despite having half the total current.},

doi = {10.1088/1741-4326/ab54fb},

journal = {Nuclear Fusion},

number = [1],

volume = [60],

place = {United States},

year = {2019},

month = {12}

}

Works referenced in this record:

##
Toroidal gyro‐Landau fluid model turbulence simulations in a nonlinear ballooning mode representation with radial modes

journal, July 1994

- Waltz, R. E.; Kerbel, G. D.; Milovich, J.
- Physics of Plasmas, Vol. 1, Issue 7

##
1.5D quasilinear model and its application on beams interacting with Alfvén eigenmodes in DIII-D

journal, September 2012

- Ghantous, K.; Gorelenkov, N. N.; Berk, H. L.
- Physics of Plasmas, Vol. 19, Issue 9

##
Energetic ion distribution resulting from neutral beam injection in tokamaks

journal, October 1976

- Gaffey, John D.
- Journal of Plasma Physics, Vol. 16, Issue 2

##
Kinetic transport simulation of energetic particles

journal, April 2016

- Sheng, He; Waltz, R. E.
- Nuclear Fusion, Vol. 56, Issue 5

##
Simulations tackle abrupt massive migrations of energetic beam ions in a tokamak plasma

journal, August 2018

- Bierwage, Andreas; Shinohara, Kouji; Todo, Yasushi
- Nature Communications, Vol. 9, Issue 1

##
ITER predictions using the GYRO verified and experimentally validated trapped gyro-Landau fluid transport model

journal, June 2011

- Kinsey, J. E.; Staebler, G. M.; Candy, J.
- Nuclear Fusion, Vol. 51, Issue 8

##
Gyrokinetic simulations of impurity, He ash and α particle transport and consequences on ITER transport modelling

journal, April 2009

- Angioni, C.; Peeters, A. G.; Pereverzev, G. V.
- Nuclear Fusion, Vol. 49, Issue 5

##
Anomalous Transport Scaling in the DIII-D Tokamak Matched by Supercomputer Simulation

journal, July 2003

- Candy, J.; Waltz, R. E.
- Physical Review Letters, Vol. 91, Issue 4

##
Nonlinear Dynamics of a Driven Mode near Marginal Stability

journal, February 1996

- Berk, H. L.; Breizman, B. N.; Pekker, M.
- Physical Review Letters, Vol. 76, Issue 8

##
Density limits in toroidal plasmas

journal, July 2002

- Greenwald, Martin
- Plasma Physics and Controlled Fusion, Vol. 44, Issue 8

##
Observation of Critical-Gradient Behavior in Alfvén-Eigenmode-Induced Fast-Ion Transport

journal, February 2016

- Collins, C. S.; Heidbrink, W. W.; Austin, M. E.
- Physical Review Letters, Vol. 116, Issue 9

##
Alfvén eigenmode stability and critical gradient energetic particle transport using the Trapped-Gyro-Landau-Fluid model

journal, July 2017

- Sheng, He; Waltz, R. E.; Staebler, G. M.
- Physics of Plasmas, Vol. 24, Issue 7

##
Prediction of the fusion alpha density profile in ITER from local marginal stability to Alfvén eigenmodes

journal, October 2014

- Waltz, R. E.; Bass, E. M.
- Nuclear Fusion, Vol. 54, Issue 10

##
Gyrokinetic simulations of mesoscale energetic particle-driven Alfvénic turbulent transport embedded in microturbulence

journal, November 2010

- Bass, E. M.; Waltz, R. E.
- Physics of Plasmas, Vol. 17, Issue 11

##
Development and validation of a predictive model for the pedestal height

journal, May 2009

- Snyder, P. B.; Groebner, R. J.; Leonard, A. W.
- Physics of Plasmas, Vol. 16, Issue 5

##
Enhanced Localized Energetic-Ion Losses Resulting from Single-Pass Interactions with Alfvén Eigenmodes

journal, February 2013

- Chen, X.; Austin, M. E.; Fisher, R. K.
- Physical Review Letters, Vol. 110, Issue 6

##
Development and validation of a critical gradient energetic particle driven Alfven eigenmode transport model for DIII-D tilted neutral beam experiments

journal, October 2015

- Waltz, R. E.; Bass, E. M.; Heidbrink, W. W.
- Nuclear Fusion, Vol. 55, Issue 12

##
A theory-based transport model with comprehensive physics

journal, May 2007

- Staebler, G. M.; Kinsey, J. E.; Waltz, R. E.
- Physics of Plasmas, Vol. 14, Issue 5

##
Gyrokinetic simulation of global and local Alfvén eigenmodes driven by energetic particles in a DIII-D discharge

journal, January 2013

- Bass, E. M.; Waltz, R. E.
- Physics of Plasmas, Vol. 20, Issue 1

##
Turbulent transport of alpha particles in reactor plasmas

journal, November 2006

- Estrada-Mila, C.; Candy, J.; Waltz, R. E.
- Physics of Plasmas, Vol. 13, Issue 11

##
Test-electron analysis of the magnetic reconnection topology

journal, December 2017

- Borgogno, D.; Perona, A.; Grasso, D.
- Physics of Plasmas, Vol. 24, Issue 12

##
The effect of the fast-ion profile on Alfvén eigenmode stability

journal, August 2013

- Heidbrink, W. W.; Van Zeeland, M. A.; Austin, M. E.
- Nuclear Fusion, Vol. 53, Issue 9

##
Energetic particle physics in fusion research in preparation for burning plasma experiments

journal, November 2014

- Gorelenkov, N. N.; Pinches, S. D.; Toi, K.
- Nuclear Fusion, Vol. 54, Issue 12

##
Multi-phase hybrid simulation of energetic particle driven magnetohydrodynamic instabilities in tokamak plasmas

journal, November 2016

- Todo, Y.
- New Journal of Physics, Vol. 18, Issue 11