# Presentation: 567464

## Super-Alfvénic ion instabilities and transport

- E. Fredrickson *for the NSTX Team*
**NSTX PAC-19 meeting**
- Feb. 22-24, 2006
- Princeton Plasma Physics Laboratory

***Culham Sci Ctr***
***U St. Andrews***
***York U***
***Chubu U***
***Fukui U***
***Hiroshima U***
***Hyogo U***
***Kyoto U***
***Kyushu U***
***Kyushu Tokai U***
***NIFS***
***Niigata U***
***U Tokyo***
***JAERI***
***Hebrew U***
***Ioffe Inst***
***RRC Kurchatov Inst***
***TRINITI***
***KBSI***
***KAIST***
***ENEA, Frascati***
***CEA, Cadarache***
***IPP, J******ü******lich***
***IPP, Garching***
***ASCR, Czech Rep***
***U Quebec***

***College W&M***
***Colorado Sch Mines***
***Columbia U***
***Comp-X***
***General Atomics***
***INEL***
***Johns Hopkins U***
***LANL***
***LLNL***
***Lodestar***
***MIT***
***Nova Photonics***
***New York U***
***Old Dominion U***
***ORNL***
***PPPL***
***PSI***
***Princeton U***
***SNL***
***Think Tank, Inc.***
***UC Davis***
***UC Irvine***
***UCLA***
***UCSD***
***U Colorado***
***U Maryland***
***U Rochester***
***U Washington***
***U Wisconsin***

**Notes:**
Use Helvetica
More introduction to rest of talk

## NSTX accesses ITER-relevant phase-space island overlap regime

- ITER in new, small * regime for fast ion transport
- k ≈ 1 means "short" wavelength Alfvén modes
- fast ion transport from interaction of many modes (MDC-9)

- NSTX also routinely operates with super-Alfvénic fast ions;
- q measured in super-Alfvénic ion regime
- 'Avalanch' or 'sea-of-TAE' transport seen
- Predicting effect of fast ion transport on beam driven currents is high priority

## NSTX can study nonlinear dynamics

_**Fast ion transport:**_
- sFLIP, NPA, ssNPA
- neutrons

**Predictive**
**Capability**

*NSTX can study nonlinear dynamics*

- EFIT, TRANSP

- M3D, HYM

- Nova, Hinst

- Orbit

## Physics goals for fast ion physics studies

*Physics goals for fast ion physics studies*

- 2006 (MSE, sFLIP, ssNPA, polarization diagnostic)
- Determination of TAE Avalanche threshold, ORBIT simulations of fast ion losses
- Measurement of internal mode amplitude and structure,
*together* with current profile and fast ion loss measurements
- Validate bootstrap/beam-driven current models
- Develop fast -ion MHD-quiescent discharge
- Compare J(r) evolution in plasmas with energetic particle MHD
- 2007 (fast FireTip, faster scanning reflectometer?)
- Study parameter scaling of mode structure, amplitude, stability and fast ion losses
- Dedicated experiment to compare J(r) evolution with/without fast-ion MHD.

*(To achieve **2007 milestone** supporting **ITPA MDC-9**)*

## ...continued

*...**continued*

- 2008 - Fast Ion Dalpha (FIDA) diagnostic
- Improved radial profile measurement of Fast Ion MHD induced redistribution
- Continuation EPM/TAE physics studies
- Contingency/piggy-back experiments:
- Stochastic heating threshold for CAE/GAE
- GAE/CAE phase-space structures (hole-clumps)
- (Doppler-shifted cyclotron resonance & universal drive)
- External excitation of CAE/GAE (TAE?)
- Role of "saturated" EPMs
- Non-linear mode coupling (3-wave coupling)

## 2006: Experiment to study fast-ion interactions with TAE and EPM

*2006: Experiment to study fast-ion interactions with TAE and EPM*

- Test models for EPM-induced fast ion loss:
- Detailed structure of mode, frequency
- Test models for EPM stability:
- Bounce or precession-drift resonance?
- Study "sea-of-TAE"-induced fast ion losses
- Measurements of multiple mode amplitudes
- Test non-linear models of TAE stability
- Avalanche or domino model (Berk, et al., PoP **2** '95, 3007)
- Develop models for non-linear mode interactions (3-wave coupling)

## TAE bursts suggest "Avalanche" physics

*TAE bursts suggest "Avalanche" physics*

- No correlation of repetitive small bursts; increased amplitude  leads to strong multiple mode burst

- Weak chirping/bursting simulated with M3D-K (Fu)
- Strong bursts consistent with model of "island" overlap in fast ion phase space
- TAE have multiple resonances, more complex physics

- Berk, et al., PoP **2** 3007

## Nova often shows phase inversion - seen for higher n's

*Reflectometer shows "sea of TAE" *

- N. Crocker, S. Kubota, W. Peebles, UCLA

- Mode amplitude can be used to infer size of phase space island
- Data from before MSE available; great uncertainty in q-profile

## sFLIP data can be used to benchmark ORBIT simulations 

- Relatively new capability
- Pitch angle, energy of lost fast ions is measured
- Loss at highest beam energy, range of pitch angles
- Correlate with ORBIT or M3D/HYM simulations

- (Fast camera provided by JAERI)

## Slide 10

## Validate bootstrap/beam driven current physics
Develop fast-ion-MHD-quiescent target plasma
Document current profile evolution with MSE
Identify stability thresholds for EPM/TAE
Determine MHD-free operational range
Provides basis for interpretation of effect of TAE/EPM on beam-driven current - feeds into 2007 milestone

*2006: Validate beam-driven and bootstrap current models*

- Validate bootstrap/beam driven current physics
- Develop fast-ion-MHD-quiescent target plasma
- Document current profile evolution with MSE
- Identify stability thresholds for EPM/TAE
- Determine MHD-free operational range
- Provides basis for interpretation of effect of TAE/EPM on beam-driven current - feeds into 2007 milestone

## Non-linear interactions through phase space structures

*Non-linear interactions through phase space structures*

- HHFW stabilization observed
- introduces effective collisionality operator on fast ion distribution
- Potential to disrupt avalanch

- Window onto phase space structures in realistic, multi-dimensional phase space.
- HYM code (E. Belova) capable on non-linear CAE/GAE simulations.

## NSTX uniquely suited to study non-linear multi-mode interactions relevant to ITER

- NSTX fast ion loss occur with multiple modes, "sea of TAE", as predicted for ITER
- NSTX has comprehensive diagnostic set in the super-Alfvénic fast ion regime
- 2006 experiments address ITPA MDC-9, fast ion redistribution by Alfven modes
- In 2007 will complete experiments to measure effect of TAE/EPM on beam-driven current profile.
- TAE/EPM (CAE) interact, perhaps synergistically
- Interactions can be through non-linear phase-space coupling
- Direct non-linear coupling is also being investigated
- Study of CAE-induced phase-space structures provide window on realistic, multi-dimensional phase space resonances

**Notes:**
Biggest losses are from EPM, ITER