# Presentation: 694681

##                                            Supported by   

**Masa Ono, PPPL**
*For the NSTX Research Team*

***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***

***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***
***JAEA***
***Hebrew U***
***Ioffe Inst***
***RRC Kurchatov Inst***
***TRINITI***
***KBSI***
***KAIST***
***POSTECH***
***ASIPP***
***ENEA, Frascati***
***CEA, Cadarache***
***IPP, J******ü******lich***
***IPP, Garching***
***ASCR, Czech Rep***
***U Quebec***

**                                           ****Supported by   **

**4th IAEA Technical Meeting on Spherical Tori &**
**14th International Workshop on Spherical Torus**
**ENEA, Frascati**
**7 – 10 October 2008**

## Talk Outline

**NSTX Mission and Facility / Diagnostic Status Overview**
**Highlights and Facility Diagnostic Plans Organized by Science Topical Areas **
**MHD (M. Bell)**
**T&T (M. Bell)**
**Boundary Physics (M. Bell)**
**HHFW, EBW, and Energetic Particles**
**Start-up and Ramp-up (R. Raman)**
**NSTX Near Term Plans (5 Year Plan)**
**Conclusions**

## NSTX Facility Overview

_**Baseline Parameters**_
- Major Radius 0.85 m
- Minor Radius 0.68 m
- Elongation 1.8 -  3.0
- Triangularity 0.2 - 0.8
- Plasma Current
-     1 MA (1.5 MA peak)
- Toroidal Field
-      0.35 - 0.55 T
- Heating and CD
-    7 MW NBI (2 sec)
-    5 MWNBI (5 sec)
-    6 MW HHFW (5 sec)
-    0.2 MA CHI
- Pulse Length
-    ~ 1 sec at 0.55 T
-    ~ 2 sec at 0.38 T

**NSTX Facility Overview**

## NSTX Device Cross-Section and VV Internal ComponentsRemovable Center-Stack Design

## NSTX Mission Elements 

**Establish attractive ST operating scenarios & configurations**
**Long-term goal:**** **** Understand and utilize advantages of the ST configuration for addressing key gaps between ITER performance and the expected performance of DEMO (including an ST-DEMO)**
**Complement tokamak physics and support ITER **
**Exploit unique ST features to improve tokamak understanding**
**Contribute to ITER final design activities and research preparation**
**Participate strongly in ITPA and U.S. BPO, benefit from tokamak R&D**
**Understand unique physics properties of the ST**
**Understand impact of low A, very high ********, high v****fast ****/ v****A****, ...**
**ST understanding underpins missions 1 and 2 above**

## 2007 FESAC Priorities Panel prioritized issues for getting from ITER to DEMO ST can contribute to all FESAC Priority Panel “Themes”

**A.****	****Creating predictable high-performance steady-state plasmas**
**Measurement**
**Integration of high-performance, steady-state, burning plasmas**
**Validated predictive modeling **
**Control**
**Off-normal plasma events**
**Plasma modification by auxiliary systems**
**Magnets**
**B.****	****Taming the plasma material Interface (PMI)**
**Plasma wall interactions**
**Plasma facing components**
**RF antennas, launching structures, and other internal structures**
**C.****	****Harnessing fusion power**
**Fusion fuel cycle**
**Power extraction**
**Materials science in the fusion environment**
**Safety**

*** ******ST offers simplified, maintainable, affordable magnets for DEMO***

***ST offers high heat flux at small size and cost for PMI R&D***

***ST offers high neutron flux at small size and cost for testing fusion nuclear components***

*** ******ST expands knowledge-base for all aspects of Theme A***

## HHFW For Electron Heating and Current Drivefor Start-up, Ramp-Up, and Sustainment

**HHFW For Electron Heating and Current Drive****for Start-up, Ramp-Up, and Sustainment**

**HHFW Antenna Upgrades**

**HHFW Antenna Array**

**• ****Double-feed upgrade for higher power in 2009 to utilize full power under various load conditions**
**• ****ELM resilience system upgrade in 2010 with ORNLfor H-mode operation **

**• ****Twelve antennas**
**• ****Six 1 MW transmitters **
**• ****Real time phasing**
**• ****Top-fed**
**• ****Wave reflectometers **
**• ****Edge rf probes**

*** ******Feed-through voltage reduced to double power handing capability***
***Mid-plane ground to optimize HHFW launching***

## D, He Plasmas Heated to 5 keV with 3 MW HHFW at k|| = 14 m-1(Lithium has helped HHFW performance in deuterium, H-mode, and NBI)

**D, He Plasmas Heated to 5 keV with 3 MW HHFW at k****||**** ****= 14 m****-1****(Lithium has helped HHFW performance in deuterium, H-mode, and NBI)**

***P. Ryan, et al***
***C. K. Phillips et al.,(IAEA)***

## HHFW-Induced Increase in Electron Stored Energy Comparable in Helium and D Plasmas

- Prf ~ 1.8 MW in He-4 plasmas
- (~ 230 ms duration)

- Prf ~ 1.1 MW in D plasmas
- (~230 ms duration)

- Noticeable increase in WEF with -30° phasing in D plasmas with Li edge conditioning, even with shorter rf duration (67 ms)

**HHFW-Induced Increase in Electron Stored Energy Comparable in Helium and D Plasmas**

## 
Experiments starting to study HHFW coupling into deuterium H-modes with upgraded antennas

- Experiments starting to study HHFW coupling into deuterium H-modes with upgraded antennas

**HHFW Heating of NBI-Driven H-mode Plasmas**

## Productive EBW ResearchEBW Current Drive Significantly Increases Performance for Future STs

**Productive EBW Research****EBW Current Drive Significantly Increases Performance for Future STs**

**Remotely Steered EBW Emission System for Coupling Study**

***S. J. Diem, G. Taylor et al., (IAEA)***
***S. J. Diem PhD Thesis***

## LIThium EvaporatoR (LITER) provides PFC Conditioning Tool to Modify Plasma Edge 

- B-X-O coupling depends on Ln and Te
- Li conditioning   Te &   ne near MC
- Reduction in edge ne moves MC
-       layer to LCFS where Te ~ 20 eV

***H. Kugel, et al, PoP***

## Better Trad agreement with EBE simulation in Lithium conditioned plasma

**    ****	****	****T****rad**** (measured)**
**	****	****T****rad**** (sim., no collisions)**
**	****	****T****rad ****(sim., with collisions)**
**For highest Li evaporation                                                rate, 19 mg/min:**
**Measured T****rad****~0.4 keV**
**Simulated T****rad****~0.6 keV**
**For 0 mg/min:**
**Measured T****rad****~0.1 keV**
**Simulated T****rad**** ~0.4 keV**

**Control of edge conditions allows for good coupling to EBW**

## Extensive Energetic Particle Diagnostic CapabilityMeasures Fast Ion Properties

**FIDA diagnostic on NSTX (2008)**

**Fast neutron rate monitors**
**Scanning NPA; **
***ssNPA; 4-channel compact NPA***
**sFLIP; scintillator lost ion probe,**
**iFLIP; Faraday cup lost ion probes**
***FIDA; spatial profile, energy resolved  (2008)***

***Collaboration contributions***

## Quasi-Continuous RSAE and Bursting AE Avalanche Produce Ion Losses

**Losses increase while frequency still increasing**
**Avalanche also produces burst of loss**

**Colors designate n numbers**

**s-FLIP Scintillator Detector**
** ****Principle of Operation**

***D. Darrow, E. Fredrickson ***

## MHD Instabilities Affect Confinement of Fast Ions

**Density profile of fast ions (15 – 65 keV) deduced from Doppler-shifted D******** emission by energetic neutrals created by charge-exchange with NBI neutrals**

**During TAE avalanches, measured fast-ion losses up to 30%**
**Consistent with neutron rate drop**
**Profile remains peaked **

**Low-frequency (kink) activity redistributes fast ions outwards**
**Can destabilize Compressional Alfv****én Eigenmodes**** (CAEs) in outboard midplane region**

- Avalanche

*M. Podest**á*

***M. Podesta, APS***

## Gaps Between Present and Future STs MotivateNSTX Scientific Goals and Associated Upgrades

**1. Increase and understand ****beam-driven current lower n****e****, ***********
********* ******Test increased NBI-CD with density reduction, higher T******e******, higher NBI power***
**2. Increase and understand H-mode confinement at low ***********
********* ******Determine modes responsible for transport, determine scaling vs. B******T******, I******P ******, P******HEAT***
**3. Demonstrate and understand non-inductive start-up and ****   ramp-up**
********* ******Increase ramp-up heating power & current drive to test I******P****** ramp-up techniques***
**4. Sustain ********N ****and understand MHD near and above no-wall ****   limit**
********* ******Improve control of ************, RWM/EF, rotation and q profiles to optimize stability  ***

## New NSTX Diagnostic Capabilities All diagnostics measure close to mid-plane to facilitate data analysis

**P-CHERS**
**75 Ch**

**MSE-LIF (FY09-10)**

** ****V********(r)**

**E****r****(r), B(r)**

***NBI paths***

**32 Ch BES - Low-k to comprement high-k**

***R. Bell***

***E. Foley, F. Levinton ***

***G. McKee, B. Stratton***

## Near Term upgrades will enable unique and exciting  research in support of 3 highest priority research goals

**Measure full wave-number spectrum of turbulence to determine modes responsible for anomalous transport**

**Reduce electron density using **_***liquid***_** lithium, improve understanding of how Li improves confinement and reduces/eliminates ELMs**
**Implement liquid lithium divertor (LLD)**
***LLD-I = porous Mo surface bonded to heated Cu plate***

**Asses if higher power HHFW can ramp-up I****P**** in H-mode (BS+RF overdrive) and heat high-********N**** NBI H-mode scenarios**
****** ****Upgrade HHFW system for higher P****RF**** + ELM resilience**

****** ****Implement BES to complement existing high-k scattering diagnostic**

***ORNL, PPPL ***

***U. Wisconsin, PPPL ***

***SNL, PPPL ***

## New High-Performance Center-Stack will Expand Operational Space Toward Next-Step STs 

**6.0**

**7.0**

**8.0**

**I****P****=1.4MA**

**New High-Performance Center-Stack will ****Expand Operational Space Toward Next-Step STs **

**6.0**

**7.0**

**8.0**

**I****P****=1.4MA**

**•****	****Determine if the favorable**** ion and electron confinement scaling****, and turbulence variation, observed in NSTX continues to higher magnetic fields and lower collisionality. **
**•****	****Determine if the ****MHD stability ****of neoclassical tearing modes and resistive wall modes is favorable at lower collisionality and higher magnetic field.  **
**•****	****Using the higher magnetic field, which ****improves the efficiency of plasma heating and current drive**** both for RF and NBI, push further towards fully non-inductive start-up and current sustainment for long pulses.**

## New Center Stack will Utilize Interchangeable Design but will Incorporate Additional Key Improvements 

**New Center Stack will Utilize Interchangeable Design but will Incorporate Additional Key Improvements **

**+ 13 cm radial build**

**• ****Improved TF joint design to minimize lift off**
**• ****PF 1A, 1B, and 1C at both top and bottom for improved divertor control flexibility (e.g. very high expansion for X-divertor)**
**• ****Incorporate additional capabilities (e.g. pellet guide tube for inside launch)**

## Addition of Second NBI Will Produce Plasma Parameters Relevant for Next-Step STs 

**2nd NBI**

**Addition of Second NBI Will Produce Plasma Parameters Relevant for Next-Step STs **

**Pump**
**Duct**

** •****	****Extend ****Confinement scalings ****to higher power and plasma pressure, and lower collisionality, closer to next-step ST devices.**
** •****	****Test ****Magneto-hydrodynamic stability ****at higher plasma pressure to explore the limits that could be encountered in future devices.**
** •****	****Challenge the divertor ****in NSTX beyond the capabilities of any other device in the world (in terms of the scaling parameter, P/R)**

**Greatly enhanced capabilities**
**Doubles P****NBI**** from 7 to 14 MW (at 95 keV, 2s), 5 to 10 MW (at 80 keV, 5s)**
**Higher CD Efficiency and j(r) control**

## More Tangential Injection Enables Profile Control and Fully-Non-Inductive Current-Drive Scenarios

**More Tangential Injection Enables Profile Control and Fully-Non-Inductive Current-Drive Scenarios**

**• ****Test predictions that more ****tangential injection ****increases beam current drive efficiency and can sustain a broadened and more MHD stable current profile. **
**• ****Increased Alfvén eigenmode activity**** and fast-ion redistribution/loss could result from more tangential injection and increased fast-ion pressure.    **
**• ****Test plasma ****ramp-up using beam injection and demonstrate ****fully non-inductive sustainment**** to simulate the scenarios planned for future ST devices.****  **

## NSTX is Assessing Potential of the ST for fusion

**NSTX produced exciting results in Waves and Energetic Particles:**
**Efficient HHFW electron heating is demonstrated in deuterium to ~ 5 keV.**
**Lithium has helped HHFW performance in H-mode and with NBI.**
**EBW emission improvement with Lithium in H-mode is shown to be reduced edge collisional absorption.**
**FIDA energetic particle diagnostic is producing important data on MHD-induced energetic particle transport.**
**NSTX is implementing cutting edge advanced diagnostics**
**75 channel P-CHERS is yielding important results.**
**32 channel BES system is being installed to complement high-k.**
**MSE-LIF will measure E****r**** and B****total **** for the first time.**
**Upgrades will greatly expand the scientific capabilities of NSTX for next-Step STs:**
**Access and understand impact of reduced collisionality on ST physics at higher B****T**** and I****p**** with new center-stack**
**Access and understand impact of varied NBI deposition profile for fully non-inductive sustainment **