OPERATIONAL SCENARIO of KTM Dokuka V.N., Khayrutdinov R.R. TRINITI, Russia O u t l i n e Goal of the work The DINA code capabilities Formulation of the problem Examples of simulations Conclusions Future work

Goal of the work

Equilibrium and transport modeling code DINA DINA is Free Boundary Resistive MHD and Transport-Modeling Plasma Simulation Code The following problems for plasma can be solved: Plasma position and shape control; Current ramp up and shut down simulations; Scenarios of heating, fuelling, burn and non- inductive current drive; Disruption and VDE simulations (time evolution, halo currents and run away electron effects); Plasma equilibrium reconstruction; Simulation of experiments in fitting mode using experimental magnetic and PF measurements Modeling of plasma initiation and dynamic null formation.

DINA code applications DINA code has been benchmarked with PET, ASTRA and TSC codes. Equilibrium part was verified to the EFIT code Control, shaping, equilibrium evolution have been validated against DIII-D, TCV and JT-60 experimental data Disruptions have been studied at DIII-D, JT- 60, Asdex-U and COMPASS-D devices Breakdown study at NSTX and plasma ramp-up at JT-60 and DIII-D Discharge simulations at FTU, GLOBUS and T11 tokamaks Selection of plasma parameters for ITER, IGNITOR, KTM and KSTAR projects Modeling of plasma shape and position control for MAST, TCV and DIII-D

Theoretical and numerical analysis of plasma-physical processes at KTM

I P = 0.75 MA P aux = 5 MW Vacuum creation, gas puff Toroidal magnetic field creation Plasma current initiation Auxiliary heating B t = 1 T Plasma current ramp-up Plasma current flat-top Plasma current shut-down Scheme of discharge scenario at KTM

The previous KTM scenario (2) Plasma current current density, boundary and equilibrium during ramp-up

Ramp-up (1) Results of plasma initiation calculation are inputs for ramp-up simulation ( values of PF coil and vessel and total plasma currents, plasma current density) Set of snapshot calculations are used to choose waveforms for PF coil and plasma current and for plasma boundary ; Transition from limited to X-point plasma is carefully modeled; Optimization of Volt-second consumption of inductor-solenoid is carried out; Ramp-up time ( speed of ramp-up) is optimized to avoid “skin currents” at plasma boundary; Pf coil currents and density waveforms are carefully programmed to avoid plasma instability and runaway current

Dina calculates plasma equilibrium with programmed PF currents Programmed parameters are plasma density, plasma current, auxiliary heating power To simulate plasma evolution one must use a controller. Today it is absent We had to apply DINA means for controlling plasma current by using CS current, and to control R-Z position by using PF3 and HFC currents respectively How to create PF programmed set: The initial PF data was obtained in the end of stage of plasma initiation At first the plasma configurations at the end of ramp up stage and for flat top are calculated Techniques used for creation PF scenario

Programmed inputs for DINA n(t) P(t) Ip(t) DINA PF(t)

Techniques used for creation PF scenario (continue) Having used such a programmed PF currents, we find out that plasma configuration becomes wrong from some moment. To stop simulation at this moment! To write required information for fulfilling the next step To calculate a static desired plasma configuration by taking into account information concerning plasma current profile and vacuum vessel filaments currents obtained at some previous moment A new PF currents should be included in PF programmed set To carry out simulation up to this moment. To repeat procedure of improving PF current data for achieving good agreement To continue simulation further

A set of initial snapshot calculations time= 9 ms time= 279 ms time= 499 ms time= 3999 ms

An initial set of programmed PF currents

Ramp –up (initial equilibrium) Plasma equilibrium during ramp-up

Equilibrium at the end of ramp-up Plasma equilibrium during ramp-up

Ramp –up (profiles) Plasma current density profiles Safety factor profiles Electron temperature profiles Bootstrap current profiles

Plasma parameters on the stage of ramp up Time3 ms280 ms Plasma current, Ip, kA Poloidal beta,  p Minor radius, a, cm Major radius, R, cm Vacuum vessel current I vv, kA Averaged electron density,  n e14  Elongation,  Averaged electron temperature,  T e , eV Averaged ion temperature,  T i , eV Safety factor q axis Safety factor q bound Normalized beta,  N Confinement time,  E, ms Resistive loop voltage, U res, V Bootstrap current, I bs, kA Ohmic heating, P , MW Auxiliary heating, P ICRH, MW-- R-coordinate of X-point, cm Z-coordinate of X-point,cm

Flat-top Set of snapshot calculations are used to choose waveforms for PF coil and plasma current and for plasma boundary ; Optimization of Volt-second consumption of inductor-solenoid is carried out for Ohmic and Auxiliary Heating scenarios Different scaling-laws for heat conductivity ( Neo-Alcator, T-11, ITER-98py ) are used Different profiles of auxiliary heating deposition can be applied Optimization of scenario to avoid MHD instabilities X-point swiping to minimize thermal load at divertor

Plasma parameters on flat top Time280+ ms4500m s Plasma current, Ip, kA Poloidal beta,  p Minor radius, a, cm Major radius, R, cm Vacuum vessel current I vv, kA Averaged electron density,  n e14  Elongation,  1.76 Averaged electron temperature,  T e , eV Averaged ion temperature,  T i , eV Safety factor q axis Safety factor q bound Normalized beta,  N Confinement time,  E, ms Resistive loop voltage, U res, V Bootstrap current, I bs, kA Ohmic heating, P , MW Auxiliary heating, P ICRH, MW5.0 R-coordinate of X-point, cm Z-coordinate of X-point,cm

PF currents scenario (PF1-PF6, CS, HFC)

Flat-top (typical configuration) Plasma equilibrium during flat-top

Evolution of plasma parameters 1 1.Plasma current 2.Poloidal beta 3.Minor radius 4.Horizontal magnetic axis

Evolution of plasma parameters 2 1.Averaged electron density 2.Elongation 3.Internal inductance 4.Vacuum vessel current

Evolution of plasma parameters 3 1.Averaged ion temperature 2.Safety factor on magnetic axis 3.Safety factor on the plasma boundary 4.Averaged electron temperature

Evolution of plasma parameters 4 1.Electron density in the plasma center 2.Global confinement time 3.Major plasma radius 4.Resistive loop voltage

Evolution of plasma parameters 5 1.Vertical position of magnetic axis 2.Bootstrap current 3.beta 4.Normalized beta

Evolution of plasma parameters 6 1.Ion temperature on magnetic axis 2.Auxiliary heating (ICRH) 3.Electron temperature on magnetic axis 4.Resistive loop Volt-seconds

Evolution of plasma parameters 7 1.Total Volt-seconds 2.Plasma Volt-seconds 3.External Volt-seconds 4.Ion confinement time

Evolution of plasma parameters 8 1.Ion confinement time 2.Volt-seconds of PF (without CS) 3.Volt-seconds of CS 4.Ohmic heating power

Evolution of plasma parameters 9 1.Minor radius (95%) 2.Upper elongation (95%) 3.Down elongation (95%) 4.Elongation (95%)

Evolution of plasma parameters 10 1.Upper triangularity (95%) 2.Down triangularity (95%) 3.Triangularity (95%) 4.Horizontal position of magnetic axis

Evolution of plasma parameters 11 1.Z-coordinate of X-point 2.Current in upper passive plate 3.Current in lower passive plate 4.R-coordinate of X-point

Flat-top (profiles - 1) Plasma current density profiles Safety factor profiles Electron temperature profiles Bootstrap current profiles

Flat-top (profiles –2 ) Plasma current density profiles Safety factor profiles Electron temperature profiles Bootstrap current profiles

Flat-top (profiles –3) Plasma current density profiles Safety factor profiles Electron temperature profiles Bootstrap current profiles

Volt-seconds balance

Conclusions The creation of scenario for KTM including ramp-up and flat-top stages have been carried out Optimization of ramp-up process helped to save Volt-seconds consumptions from PF system Simulations of Ohmic and ICRF heating scenario show a possibility to achieve stable plasma parameters

Future work Additional work on development of integrated plasma shape and position controllers is required Integration of 2D-breakdown and DINA codes to do “all” scenario simulation ( breakdown-shutdown) in one step is desirable A more accurate wave Altoke-e code, consistent with DINA, is planned to use for modeling ICRF heating

Simulink model for R-Z control of KTM

The results of simulation of R-Z control for KTM