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Experimental Summary

• Scenarios• Diagnostics• Runaways• Instabilities• Fast-ion Transport

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Disclaimer

If I lost your summary slide, I’m sorry!

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Outline

• Scenarios• Diagnostics• Runaways• Instabilities• Fast-ion Transport

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Deuterium beams are now injected in LHD

• A comprehensive set of neutron instruments enable improved diagnosis of confined fast ions

O-14 Isobe

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P-21Deuterium beams are employed in an investigation of collisional processes

P-21 Nuga

• Used to validate a Fokker-Planck code

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Neutral-beam injection experiments are now conducted on TCV

• NPA & FIDA data suggest confinement below classical

O/P-17 Testa

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An “afterglow” regime with alpha-driven TAEs seems accessible in JET

O-3 Dumont

• Look for alpha-driven TAEs after beams shut off as in TFTR

• Can produce high neutron rates w/o ICRF• TRANSP prediction based on obtained

discharge is promising

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Observation of MeV range ions in ICRH experiments with the three ions scenarios at JET

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- A novel ICRH scheme that exploits the favourable polarization properties of the electric field at the L cutoff layer in 3 species plasmas has been developed

- MeV range fast ions were generated and observed by a number of diagnostics, especially gamma-ray and neutron spectroscopy. Fast ion driven MHD leads to redistribution and losses of the most energetic ions (2-3 MeV)

interesting new scheme for fast ion physics studies!

- The scheme can be applied to generate MeV range 4He ions as a way to anticipate α particle physics and prepare DT experiments at JET and ITER

Increased gamma-ray emission (larger fast ion content) with the 3 ion scheme (red) compared to minority heating (blue) for the same

RF power

Tailoring of the fast ion profile by changes of the antenna phasing from dipole (left) to π/2 (right) as demonstrated by poloidal images

of gamma-ray emission from the plasma

M. Nocente, Y. Kazakov et al.

I-6 Nocente

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Outline

• Scenarios• Diagnostics• Runaways• Instabilities• Fast-ion Transport

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An imaging neutral particle analyzer is being installed on DIII-D

pinhole

stripping foils

collimation box• The neutrals are stripped by a

carbon foil• The “detector” is a scintillator-based

magnetic spectrometer as in a Fast-ion Loss Detector

P-4 Xiaodi Du

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On NSTX-U, FIDA signals from edge neutrals are as large as signals from injected neutrals

• Red is “active” signal• Blue is “passive” signal

P-9 Guangzhou Hao

• Edge neutrals also important in edge FIDA measurements in ASDEX-U (Jacobsen)

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A gamma-ray diagnostic for lost alphas is proposed for ITER

• A reference view is needed for background• Estimated signal-to-noise: 1/3

O-15 & I-3 Kiptily

Fast deuterons & α-particles from nuclear reactions identified and the anomalous neutron rate in H-plasmas were explained

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Classical Distribution Reconstruction

F(E,Rm)

F(Rm,p)

F(E,p)

F(E,Rm)

F(Rm,p)

F(E,p)

Orbit-based weight functions enable improved inference of distribution function

O-11 Stagner

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New analysis of reflectometer data yields larger amplitudes for CAE & GAE eigenfunctions

GAEs

CAEs

I-7 Crocker

• Still doesn’t explain observed electron transport• Many similarities but some differences from

calculated modes

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Outline

• Scenarios• Diagnostics• Runaways• Instabilities• Fast-ion Transport

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QM/kinetic modeling explains stronginfluence of partially ionized impurities on runaway beams

• Massive gas injection dissipates beam

I-5 Papp

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Synchrotron emission used to infer runaway distribution function

O-8 Hoppe

• Weight function for synchrotron image depends on forward cone, synchrotron rate (B), line integral, and camera sensitivity

18 A. Lvovskiy/IAEA-TM-EP/9-2017

Synchrotron radiation limits hardness of gamma spectrumT1

T1

T2

T2

T3

T3

BT increase affects high-energy RE the most

O-9 Lvovskiy

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A new code models the runaway distribution function

P-32 Spong

• Whistler waves driven by runaways were observed for the first time

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Runaways drive whistler & plasma waves in different parts of phase space

P-43 Chang Liu

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Outline

• Scenarios• Diagnostics• Runaways• Instabilities• Fast-ion Transport

Measured frequencies fci at LFS and HFS are different and correspond to local ICR frequency fci ∝ Bt, fci ∝ 1/mi, fci ≠ f(n) Up to 9 harmonics could be resolved

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2

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ICE in Ohmic hydrogen and deuterium plasmasin TUMAN-3M in the absence of energetic particles

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f1 = 8,7 MHz

2

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5 6 7 8 9

Ion Cyclotron drift instability (ICDI) in inhomogeneous plasma was predicted by Mikhailovsky & Timofeev, J.Exp.Th.Phys. 44 (1963) 919, and Mikhailovsky, NF 11 (1971) 323,

ICDI develops at vicinity of fci and its harmonics Inhomogeneity criterion for ICDI:

⁄𝜌𝜌𝑖𝑖 𝐿𝐿 ≥ 2 ⁄𝑚𝑚𝑒𝑒 𝑚𝑚𝑖𝑖⁄1 2, 𝐿𝐿 = 1

𝑛𝑛𝑑𝑑𝑛𝑛𝑑𝑑𝑑𝑑

−1

𝜌𝜌𝑖𝑖 ≈ 0.07 cm, → 𝐿𝐿 < 2 cm - reasonable for TUMAN-3M edge ICE in NBI shots are also detected, but frequency corresponds to central ICR

P-2 Askinazi

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Central & Edge ICE observed in DIII-D

I-10 Thome

• ICE frequency spectra depends on beam geometry

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CAEs in DIII-D are sensitive to beam geometry

O-13 Tang

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TAE frequency tracks change in Alfven velocity during pellet injection

I-8 Sharapov

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JET Antenna measurements of TAE damping are consistent with calculated radiative damping

P-19 Nabais

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Chirping is common in negative triangularityplasma as theoretically predicted

O-2 Van Zeeland

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Modes change their radial structure as they chirp in frequency in TJ-II

P-17 Melnikov

Nonlinear interaction between EGAMs and TAEs is observed

P. Zs. Poloskei et al. IAEA-TCM-EP 2017 P-26

• Signal processing method was developedto investigate the possible nonlinearcoupling between different transient(chirping) plasma waves

• Dedicated experiments were carried outon ASDEX Upgrade

• Nonlinear interaction has an amplitudethreshold

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Off-axis beams drive fewer Alfvén eigenmodes

P-13 Kramer

5.6 5.7 5.8 5.9 6.00

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Freq

uenc

y [k

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Time [sec]

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bar [

1019

m-3

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Te0

[keV

]

0.0

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1.0

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tron

rate

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ECH138729

5.6 5.7 5.8 5.9 6.00

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eque

ncy

[kH

z]

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1019

m-3

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ECH138730

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tron

rate

[1013

n/s

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138730

ECH reduces Alfvén eigenmodes in LHDP-22K. Nagaoka, et al.,

The fast ion profile can be controlled by combination of IS operations and plasma positions

Highlights(case 2)Center-focused NBI deposition Broad NBI deposition

• The comparison of two plasmas with the same neutron rate indicates that AE activities were stronger with center-focus NBI deposition

• Significant reduction of AE activities with ECH were observed in LHD

How to control fast ion profile

Active Control of Alfven Eigenmodesin the AUG Tokamak

• Localized ECRH and ECCD have strong impact on AE activity

• modifications of thermal plasma profiles seem to be key

• Externally applied 3D fields can be used to manipulate the fast-ion distribution in phase-space

• Suppression / excitation of NBI driven TAEs achieved on command by varying poloidal spectrum of externally applied 3D Fields I-2 Garcia-Munoz

RJ Buttery/FES Summer Visit 2018/33

• Beam current variation at fixed voltage identifies energetic particle mode (CAE) threshold

– mode disappears as beam current decreases

– controls beam ion density directly

• Neutral beam efficiency is improved in high qmin steady state plasmas when coherent instabilities are reduced through beam IV tailoring

In-shot Control of Neutral Beam Current/Voltage Reduces Fluctuations and Improves Beam Ion Confinement

Key Enhancements: Variable Perveance Neutral Beams

P-44 Pace

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Resistive interchange modes cause large losses but can be stabilized by ECH

O-16 Ohdachi

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Fast ions alter the stability of Neoclassical Tearing Modes

O-22 Heidbrink

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Outline

• Scenarios• Diagnostics• Runaways• Instabilities• Fast-ion Transport

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Fast-ion losses from 3D fields depend sensitively on the poloidal spectrum

O-6 Junghee Kim

• Spectrum altered through coil “misalignment” in KSTAR

• Similar effects on AUG & DIII-D

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In spherical tokamaks, sawtooth transport is similar to conventional tokamaks

P-16 Deyong Liu

• Passing particles more affected than trapped particles

• Kadomtsev model overestimates transport

Beam ion acceleration during ELMs is observed in the ASDEX Upgrade tokamak

• Velocity space structuressuggest a resonantinteraction between fast-ionsand the E|| arising in the ELM crash

Measured fast ion distributionis reconstructed usingtomographic technique

• Toy model reproduces keyaspects of the accelerationmechanism:

Energy gain

Resonances

J. Galdon-Quiroga | 15th IAEA TM EP | Princeton | 5th-8th September 2017 39O-23 Galdon

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Neoclassical Tearing Modes can cause appreciable transport in ASDEX-Upgrade

• Large (2,1) mode causes reduction in FIDA profile• Modest (3,2) has no detectable effect

I-12 Jacobsen

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Resistive Interchange Mode causes large losses w/ deuterium injection

Relationship of drop rates of total neutron emission rate and magnetic fluctuation induced by EICs.

P-34 Bando

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Measured FIDA profile during strong Alfvénactivity is consistent with predicted profile

• Eigenfunctions matched to measurements

• Orbit following yields “kick” probabilities

O-1 Daniel Lin

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JET scintillator detector measures new loss phenomena

• Non-resonant losses of fusion products by fishbones

• Fast-ion losses related to EAEs

I-3 Kiptily