# Presentation: 406520

## NSTX Integrated Scenario Research Plans for 2009-2013

**NSTX Integrated Scenario Research ****Plans for 2009-2013**

**Jonathan Menard**
**For the NSTX Research Team**
** **
**National Tokamak Planning Workshop**
**MIT, Cambridge, Massachusetts**
**September 17-19, 2007**

***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***

## NSTX has made substantial progress in developing and understanding high performance plasmas w/ high non-inductive current fraction

- Routine operation near ideal-wall stability limit N ≤ 6
- Plasma quiescent until q evolves toward qMIN ≤ 1.2  core MHD
- H-mode with H98y2 > 1 at high N

- Utilized novel low-BT MSE diagnostic to validate current drive sources
- Core MHD can redistribute fast ions
- Non-inductive CD fraction up to 65%
- fBS=55%, fNBICD = 10% with N near 6

**H****98y2****=1.1**

## NSTX 5 year integration goal is to meet or exceed keydimensionless performance parameters of NHTX and ST-CTF

**     ****	****      ****NSTX full-NI target****	****	****NHTX****	****	****ST-CTF**
**A****	****	****	****	****1.5****	****	****1.8****	****	****1.5**
**H****98y2****	****	****	****1.1-1.4****	****	****1.3****	****	****1.3**
******	****	****	****	****2.6****	****	****2.8****	****	****3.0**
**q*****	****	****	****	****5.3****	****	****3.8-4.5****	****	****3.3-4.2**
******T****	****	****	****	****14%****	****	****12-16%****	****	****16-25%**
******N****	****[%-mT/MA]****	****	****6.2****	****	****4.5-5****	****	****4-5**
**f****BS****	****  ****	****	****	****0.7-0.8****	****	****0.65-0.75****	****0.45-0.55**
**f****GW****	****	****	****0.7-1.0****	****	****0.4-0.5****	****	****0.3-0.5**
_**Dimensional parameters:**_
**I****P**** [MA]****	****	****	****0.75****	****	****3-3.5****	****	****8-10**
**B****T**** [T]****	****	****	****0.55****	****	****2.0****	****	****2.5**
**R****0**** [m]****	****	****	****0.86****	****	****1.0****	****	****1.2**
**a [m]****	****	****	****0.58****	****	****0.55****	****	****0.8**
**I****P ****/ aB****T0 ****[MA/mT]****	****2.3****	****	****2.7-3.2****	****	****4-5**

## 5 year goal:   Achieve full NICD at high and confinement while advancing startup/ramp-up research for NHTX/ST-CTF/DEMO

- Full non-inductive current drive strategy and method:
- Increase BS current  **** higher P-th thru higher PHEAT and/or H-factor
- Increase NBICD and PHEAT, achieve J profile control **** 2nd NBI source
- Control and improve confinement and stability **** J profile control
- fGW < 1 & N ~ 6, ne & J equilibration **** high BT=5.5kG w/ longer flat-top
- Control ne, increase confinement  **** liquid lithium divertor (LLD)
- Sustain E, N by suppressing ELM, RWM, EF **** off-midplane 3D coils
- Plasma formation and ramp-up strategy and method:
- Increase Coaxial Helicity Injection (CHI) IP ****  higher pre-ionization, VCHI
- Optimize non-CHI start-up **** PF-only w/ PI and heating, plasma guns
- Increase early pre-ionization/heating power **** 350kW ECH/EBW system
- Extend long-pulse plasmas **** use CHI/PF/Gun for ohmic flux savings
- Ramp-up IP to full-NI target **** high-IP start-up for FW & NBI heating/CD

## Addition of 2nd NBI source with increased tangency radius of injection offers several potential advantages

- Higher PHEAT for higher P, fBS at presently sustainable H98y2  ≤ 1.2
- Increased NBICD from higher PNBI
- And higher CD efficiency of large RTAN
- Increased control of *q* profile
- Optimize *q*() for high E, fNI
- Increased research flexibility by varying:
*q*-shear for transport & MHD physics
- Heating, torque, rotation profiles
-   at higher IP and BT
- Fast-ion distribution and instabilities
- Divertor P/R and pulse-length

- NBI upgrade operational mid-FY10

## Increased RTAN NBI provides 50% higher CD efficiency andmuch more control over NBICD J|| profile than present NBI

** ****Small R****TAN**** NBI provides little variation in NBI J****||**** profile shape**
** ****Large R****TAN**** can vary NBI J****||****(0) by a factor of 8 ******** ****peaked**** to ****hollow ****J****||**

**R****TAN**
**_______**
**50cm**
**60cm**
**70cm**

**R****TAN**
**_______**
**110cm**
**120cm**
**130cm**

**NBI**

***New NBI***
*** ***
- ~60kA/MWINJ

**P****NBI****=2MW**

***Present NBI***
*** ***
- ~40kA/MWINJ

## 2nd NBI would enable control of core q and  profiles in fully non-inductively-driven scenarios using only NBI + bootstrap

- Combination of available sources can control qMIN and core q-shear
- At H98y2=1.2, J control with qMIN > 1.2 requires operation with fGW > 0.9

- Magnetic shear control could be important tool for controlling core confinement and MHD stability
- Core transport reduced in RS L-mode

- Real-time MSE, CHERS available mid-FY10

**Use 4 of 6 sources**
**E****NBI****=90keV, P****INJ ****= 8MW**
**f****GW****=0.95**

***I******P ******= 725kA, B******T******=0.55T,  ************N ******= 6.2, ************T ******= 14%***
***H******98y2 ******= 1.2, f******NICD ******= 100%, ******f************p ******= 73%***

******pol**

**R****TAN ****[cm]**
**__________________ **
** ****50,  60, 70, 130**
** ****60,  70,120,130**
**70,110,120,130**

## Parameter scans confirm higher PNBI & BT aid achievement of full non-inductive current drive using only NBI + bootstrap

**High B****T****=0.55T operation is favorable for:**
**Lower ********N**** ******** closer to ********N****=6 achieved experimentally**
**Reduced f****GW**** ******** below 1**
**Higher I****P****  (prompt loss increases rapidly for I****P**** < 600kA)**

**       ****High ********P**** expt. at 0.52T****                 H****98y2**** scan at 0.55T                   ****B****T****=0.45T**
**P****INJ ****[MW]****	****5.8****	****	****6.0****	****8.0****	****10.0****	****	****8.0**
**f****NICD****  ****	****	****0.65****	****	****1.0****	****1.0****	****1.0****	****	****1.0**
**H****98y2****	****	****1.2****	****	****1.4****	****1.2****	****1.1****	****	****1.1**
**q****MIN****	****	****1.3****	****	****1.5****	****1.35****	****1.25****	****	****1.2**
******N****	****	****	****5.7****	****	****6.1****	****6.2****	****6.3****	****	****6.6**
**f****GW****	****	****	****1.0****	****	****0.84****	****0.96****	****0.94****	****	****1.07**
**I****P**** [kA]****	****	****720****	****	****720****	****725****	****740****	****	****585**
******T****	****	****	****13.4****	****	****14.2****	****14.0****	****14.7****	****	****15.0**
******P****	****	****	****1.7****	****	****2.3****	****2.3****	****2.3****	****	****2.6**
**f****BS****	****  ****	****	****0.54****	****	****0.77****	****0.73****	****0.69****	****	****0.74**
**f****NBICD  ****	****	****0.11****	****	****0.23****	****0.27****	****0.31****	****	****0.26**

**Scenario 2 (q****MIN**** > 2, ********=2.7) explored in 2007 achieved only H****98y2**** ******** 1.1**** ******** consider 2****nd**** NBI**

**P****NBI****=8-10MW needed for full NICD if H****98y2****=1.1-1.2 and q****MIN**** ******** 1.2**

## Long-pulse integrated scenarios benefit from extended TF and OH coil operation at full BT, and require sustained density control

- Sub-cooled OH and TF (-50C-100C) provide 2.5s flat-top at BT=0.55T
- Longer flat-top needed to reach density equilibration & J relaxation at higher Te
- BT = 0.52-0.55T aids 700-750kA full-NI
- Long-pulse OH  IP=1MA for 2.5s
- Use increased NBICD of 2nd NBI source

- Liquid Lithium Divertor for D pumping
- Designed to reduce density 25-50% depending on triangularity
- Consistent with fGW > 0.8 needed for fully-NI target scenarios
- Long-pulse pumping and core fueling required for sustained density control

- Pumping upgrade in FY10

- Sub-cooling operational mid-FY10

- Initial LLD operational FY09

- Implement core fueling FY10-12

## NSTX could provide unique contributions to ELM suppression physics understanding for future ST and AT NCT and reactors

**For ST - interplay between ELM control and ********N**** > ********N-no-wall**** **(islands, flow damping)
**For ST/AT - 12 coils toroidally ******** high-n (n=6), mixed intermediate-n (n=3+n=4)**

**Investigating off-axis Non-axisymmetric Control Coils (NCC) for RMP + other MHD**

- Internal NCC attractive for edge ergodization
- n=3,4 using primary+secondary coils (48)
- n=6 using primary coils (24)
- Only few kA-turns required for each option

- NCC operational
- mid-FY12

***Internal***
***NCC Option***

## NSTX will continue to advance the integration of plasma start-up, ramp-up, and sustainment needed for ST-CTF and reactors

**In ST-CTF/DEMO, iron core could provide portion of flux needed for I****P**** ramp-up **
**NSTX FY2009-13 - Use OH to simulate iron core as needed to achieve I****P**** ramp-up**

- (12)  IP, Te, RF coupling must be sufficiently high for HHFW to be absorbed
- (2) Sufficiently high PRF, E must be achieved for IP overdrive using BS and HHFW current drive
- (23) Sufficiently high IP needed to absorb NBI, high PHEAT, E, P needed for current overdrive
- (34) Ramp-up plasma must be consistent with sustained high-fNI scenario

**I****P  ****target [kA]**

**time**

**(2)**** HHFW**

**(3)**** HFW+NBI**

**(1)**** CHI, PF, Guns, EC/EBW**

**(4)**** Sustain**

- ~300

- ~500

- ~750

**NSTX start-up and**
**ramp-up strategy:**

**Start-up/ramp-up requirements:**

## Coaxial Helicity Injection (CHI) is most successful non-solenoidal plasma start-up technique implemented thus far on NSTX

**CHI only**
**Induction only**
**CHI + induction**
** **
**CHI + induction: I****P**** = 120kA**
**(Boronization + improved PF programming)**

**2006:**  160kA of closed-flux IP

***t=9ms***

**2007:**  Reduced OH flux consumption

-  2008-09: Reduce OH flux consumption of long-pulse discharges
-  2009-10: Improve CHI & coupling to induction w/ 350kW ECH pre-ioniz.
-  2010-11: Increase closed flux current using higher VCHI  2kV
-  2011-12: Couple high-closed-flux IP CHI to NBI and HHFW
-  2012-13: Use CHI + other startup/ramp-up to produce high- discharge

***CHI ***
***Start-up***
***Plan for***
***2009-13***

## PF-only startup challenge:  coils providing VLOOP must also provide radial force balance  must control  vs. time

- 20kA achieved w/ large-area field null
- HHFW couples until plasma moves inward
**More heating needed for lower ************ ECH/EBW**

***PF-only ***
***Startup***
***Plan for***
***2009-13***

-  2009-10: Increase IP of PF-only scenarios with w/ 350kW ECH/EBW
** **2009-11: Quantify achievable IP vs. null quality and ECH power
-  2011-12: Couple highest IP PF-only scenario to HHFW, NBI
-  2012-13: Use PF + other startup/ramp-up to produce high- discharge
* *2009-13: Utilize TSC simulations to optimize ramp-up evolution

- Scenarios with large stored flux and small area field-null tested
- No plasma-current measured
**More pre-ionization power needed ******** ECH**

## Plasma-gun startup techniques from PEGASUS could be tested on NSTX to complement/enhance CHI/PF-only startup research

***Plasma Gun ***
***Startup***
***Plan for***
***2009-13***

-  2008: System design for NSTX
-  2009: Installation on NSTX and commissioning tests
-  2009-2011: Support outer PF start-up experiments
-  2010-2011: Test plasma startup using mid-plane gun
-  2011-2013: Upgrade system to higher current levels as warranted

- Outboard mid-plane gun being developed

- Plasma guns in divertor produced IP=30kA
- Successfully coupled to OH induction

*Filaments*

*Relaxed ST*

## Upgraded HHFW will assist high performance NBI-heated H-mode scenarios and improve IP ramp-up 

- HHFW heating at low IP can induce  high-P H-mode w/ VSURF, VLOOP  0
- Broad Te() best for non-OH ramp-up

- 2007:  Higher BT = 0.55kG and k|| reduce parasitic surface waves
**Significant e-heating in presence of NBI for first time in L-mode**
- Plan: extend to BT=5.5kG H-mode
- Example: early HHFW can elevate q

- Double-feed antenna for higher PRF, VRF in FY09

- Improved matching for ELM-resilience mid-FY10

**t = ****0.385s**
**     ****0.400s**
**     ****0.425s**
**     ****0.485s**

**R [cm]**

- 0s

- 0.5s

**1MW HHFW**
** ****heating**

** ****TSC modeling**

## Sustainment and Start-up/Ramp-up Research Timeline

**Liquid Lithium Divertor (LLD) + long-pulse pumping + diagnostics, fueling**

***Physics***

***Tools***

**Sustained **
**integrated**
**high performance**

**Start-up and ramp-up**

****** ****control for sustainment, strike-point and flux-expansion control for LLD**

**Assess CHI with improved pre-ionization + higher voltage**

**Implement and assess plasma gun startup**

**Optimize HHFW+NBI CD &  BS overdrive for ramp-up **

**Off-midplane 3D coils**

**Large R****TAN**** 2****nd**** NBI source**

**I****P****=0.75MA**
** ****f****NI**** = 100%**
******N**** ******** 6**
******T**** ******** 14%**
**H****98y2**** = 1.1-1.4**
**f****GW****  = 0.7-1**
******t****pulse**** >> ********skin**
** ****Small/no**** ELM**

**Sub-cooled OH and TF for 2.5s 5.5kG**

**Control n****e**** using LLD, assess NBICD, BS fractions and H****98y2**

**Increase NBICD ******** J profile control from 2****nd**** NBI**

**Develop long-pulse (********pulse ****> 2s) discharges **

**ELM control at high ********N**

**I****P**** = 0.5MA**
**f****NI**** = 100%**
******N**** ~ no-wall**
** ****H****98y2**** ****~**** 1**
**f****GW**** ******** 1**

**Couple start-up to ramp-up**

**Implement, test, utilize plasma guns**

**1MW ECH/EBW**

**350kW ECH/EBW**

**700kW ECH/EBW**

**HHFW antenna upgrade**

**Optimize HHFW/NBI coupling to start-up**

**Assess PF-only startup with improved pre-ionization + heating**

**Develop RS H-mode scenarios, assess H****98y2****, ********N****, f****NI**** vs. q, add HHFW to NBI**

**NHTX/CTF-relevant integrated performance**

## BACKUP SLIDES

## Increased RTAN increases NBICD efficiency up to 70% relative to more perpendicular injection of present sources

**Shine-through**** reduces ********NBICD**** at large R****TAN ****and low density**
**  ********130cm is maximum useful R****TAN ****for f****GW**** ******** 0.6**

**Present **
**NBI**

## Lithium evaporated primarily onto lower divertor can increase confinement, reduce impurities, and improve density control

- High evaporation rates can pump D
- Reference discharge – no Li
- 35mg/min, same fueling as reference
- 35mg/min, fueling added to increase ne

- Te and/or Ti increase and Zeff is reduced with 10-15% drop in ne
**H****98y2**** = 1.1 pre-Li ******** 1.3 post-Li**

**25% increase**

**40% increase**

**30% decrease**

**Post-Li   ****(121323)**
**Pre-Li   ****(121270)**
**t = 510ms**