Study of transport simulation on RF heated and current driven EAST plasma Siye Ding Under instruction of Prof. Baonian Wan 12/09/2009

Outline TRANSP & pTRANSP program Feature of NSTX plasma --- Transport analysis work at PPPL Preliminary results of EAST simulation Summary

TRANSP Category: Experimental Data Analysis TRANSP descended from BALDUR in the 1970s The complete system includes: –A million lines of FORTRAN code –Over 100 executable programs –Over 100 subroutines –More than 100 Man-Years invested in developing code Language code: Fortran-77, Fortran-90 and some C, C++ and Python A time dependent 1½D tokamak transport data analysis model with generalized non-circular flux surface geometry Auxiliary heating packages –NUBEAM, TORIC, LSC, TORAY

PTRANSP Predictive TRANSP –The ability of simulating numerous kinds of fusion plasma activities –Inputs: Tokamak Simulation Code (TSC) outputs Shaped boundary (required) Other self-consistent plasma parameters (optional) –The same namelist with different options –Equilibrium: TEQ –Temperature and transport model options: GLF23, MMM95, Weiland model, NClass neoclassical model, paleoclassical model, etc. –Density: assumed

Feature of energy transport in NSTX plasma Data selection  dependence at constant B t The influence of plasma current profile on  The ‘pivot’ phenomenon in  profile The influence of lithium on energy transport

 dependence on B p (or q) Parameters: I p (900kA), B t (0.48T), P heat (5.6MW), and (4.6~5.6  cm -3 ), (490~608eV) A significant influence of ngTx in the relation between  s and B p (or q) –ngTx: the abbreviation of ‘local -n e *  T i/e ’ value –units: B p in T, n e in cm -3, T i/e in eV, r is normalized magnetic surface The proportional relation between  and B p (or the inversely proportional relation between  and q )

 dependence on plasma current P cond vs ngTx and q at constant B t and different I p –No obvious dependence on I p –Plasma current profile Constant ngTx – Constant q Peaky and flat (hollow) profile

The ‘ pivot ’ phenomenon in  e  profile Governed by local current density (or current profile) –Data at constant B t (2008) –Data at different B t (2006) Ip=900kAIp=1100kA Data at different B t (2006)

The influence of lithium on energy transport Energy confinement time –Parameters: I p (kA): 800, 900 B t (T): 0.54(max), 0.51(avg), 0.48(min) P heat (MW): 4.3(max), 3.7(avg), 3.2(min) –  E increases –0mg: without-lithium data Radiated power –Local  e decreases –Large percentage of radiated power –No obvious improvement on  i

The influence of lithium on energy transport  e (direct comparison) –More than 50% reduction  i (indirect comparison) –Effective The third lithium state I p : 900kA B t : 0.47T P heat : 5MW I p : 900kA B t : 0.49T P heat : 3.6MW

EAST simulation Shot#12467: –250kA; 1.9T;1.1e19m -3 ; LSN, DN, USN; Ohmic Shot#12755: –500kA; 1.9T; 2.5e19m -3 ; DN; P LH : 450kW Theoretical transport model: –GLF23 (mainly) –MMM95 –RLW-M

EAST simulation: flux contour A B C D E

A B C D E

A B C D E

EAST simulation:  p, li and current profile Some difference between TRANSP (TSC) and EFIT

EAST simulation: different models and experiment data

EAST simulation: n e and T i/e profile n e profile: assumed by using parabolic distribution with two free index parameters T i0 : assumed to be 2/3~3/4 T e0

EAST simulation: confinement

EAST simulation: power balance Electron: –Source: Ohmic electron heating –Sink: i-e coupling, conduction Ion: –Source: i-e coupling –Sink: conduction, charge exchange loss The theory model for radiation prediction is not effective enough.

EAST simulation: energy transport

EAST simulation: LH wave injection Absorbed LH power: 85% injected LH power, similar to Ohmic power Deposition position of LH power:  ~0.1 and  ~[0.3, 0.65]

EAST simulation: LH current I Oh : 400kA; I LH : 80kA; I BS : 20kA   CD =9.95e18 AW -1 m -2

EAST simulation: region of LHW absorption 5% LH power was deposited around  ~0.1, that can not be explained in this figure.

EAST simulation: theory model and experiment data

EAST simulation: high power plasma ICRH: minority heating scheme L-H transition threshold: P loss ~1.1MW

NBI simulation

Summary Brief instruction of TRANSP/pTRANSP program Plasma current profile affects  values, including the ‘pivot’ phenomenon, via ngTx. Lithium can improve energy confinement time, enhance radiation and reduce  e more than 50% when large quantities are injected. For  i, it is effective, but not quantitative investigated. The relatively reasonable results are obtained in EAST simulation comparing with experiment data. More detailed physical analysis and operation design are under consideration.

Acknowledgement PPPLers: –Analysis: Stanley Kaye and the NSTX team –Prediction: Robert Budny –TRANSP settings and jobs monitoring: Douglas McCune and the Computational team ASIPPers: –Modeling: Xinjun Zhang, Fukun Liu, Jun Li –Experiment data: Ping Xu, Jianhua Yang, Xiaofeng Han, Jinping Qian –TSC output: Yong Guo

Thank you !