operational scenario of ktm dokuka v.n., khayrutdinov r.r. triniti, russia

OPERATIONAL SCENARIO of KTM

Dokuka V.N., Khayrutdinov R.R.

TRINITI, Russia

O u t l i n eO u t l i n e

• Goal of the work

• The DINA code capabilities

• Formulation of the problem

• Examples of simulations

• Conclusions

• Future work

• Modeling of different discharge scenarios for KTM tokamak

• Optimization of Ramp-up processes• Development of PF currents

waveforms for ramp-up and flat-top and shut-down cases

• Study OH and ICRF heating regimes with different heat conductivity scaling-laws

• Plasma vertical position stabilization Plasma vertical position stabilization controlcontrol

• Disruptions simulationDisruptions simulation• X-point position controlX-point position control

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

• Breakdown and plasma initiationBreakdown and plasma initiation• Ramp-upRamp-up• Flat-topFlat-top• Plasma Vertical StabilityPlasma Vertical Stability• DisruptionsDisruptions• Shot downShot down

IP = 0.75 MA

Paux = 5 MW

Vacuum creation, gas

puff

Toroidal magnetic field creation

Plasma current initiation

Auxiliary heating

Bt = 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)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 mstime= 9 ms time= 279 mstime= 279 ms

time= 499 mstime= 499 ms time= 3999 mstime= 3999 ms

An initial set of programmed PF currents

time, ms 0. 280. 500. 4500.

Ipf1, kA 4.50 0.94 0.04 -5.54

Ipf2, kA 11.21 0.97 2.42 -1.35

Ipf3, kA 0.48 -3.29 -3.91 -4.27

Ipf4, kA 6.19 23.39 18.86 10.42

Ipf5, kA -7.94 -12.86 -8.46 -9.42

Ipf6, kA 0.01 -3.25 -3.97 -4.28

ICS, kA 24.48 -5.10 -5.62 -26.21

IHFC, kAt -91.04 5.61 1.24 1.19

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

Time 3 ms 280 ms

Plasma current, Ip, kA 50.0 751.6

Poloidal beta, p 0.54 0.14

Minor radius, a, cm 20.1 44.9

Major radius, R, cm 115.7 89.5

Vacuum vessel current Ivv, kA 50.1 31.2

Averaged electron density, ne14 0.11 0.52

Elongation, 0.95 1.76

Averaged electron temperature, Te, eV 160. 267.

Averaged ion temperature, Ti, eV 150. 259.

Safety factor qaxis 1.29 0.99

Safety factor qbound 2.94 3.93

Normalized beta, N 0.69 0.52

Confinement time, E , ms 5.31 37.50

Resistive loop voltage, Ures, V 1.34 1.48

Bootstrap current, Ibs , kA 4.04 32.30

Ohmic heating, P , MW 0.066 1.109

Auxiliary heating, PICRH , MW - -

R-coordinate of X-point, cm 137.50 77.53

Z-coordinate of X-point,cm 30.50 -58.60

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

Time 280+ ms 4500ms

Plasma current, Ip, kA 751.6 752.2

Poloidal beta, p 0.14 0.60

Minor radius, a, cm 44.9 44.6

Major radius, R, cm 89.5 89.9

Vacuum vessel current Ivv, kA 31.2 2.1

Averaged electron density, ne14 0.52 0.53

Elongation, 1.76 1.76

Averaged electron temperature, Te, eV 267. 1221.

Averaged ion temperature, Ti, eV 259. 1006.

Safety factor qaxis 0.99 0.93

Safety factor qbound 3.93 3.99

Normalized beta, N 0.52 2.32

Confinement time, E , ms 37.50 29.46

Resistive loop voltage, Ures, V 1.48 0.18

Bootstrap current, Ibs , kA 32.30 207.14

Ohmic heating, P , MW 1.109 0.132

Auxiliary heating, PICRH , MW 5.0 5.0

R-coordinate of X-point, cm 77.53 73.26

Z-coordinate of X-point,cm -58.60 -60.00

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

Flat-top (typical configuration)

Plasma equilibrium during flat-top

Evolution of plasma parameters 1

1. Plasma current2. Poloidal beta3. Minor radius4. Horizontal magnetic axis


1. Averaged electron density 2. Elongation3. Internal inductance4. Vacuum vessel current


1. Averaged ion temperature2. Safety factor on magnetic axis3. Safety factor on the plasma boundary4. Averaged electron temperature


1. Electron density in the plasma center2. Global confinement time3. Major plasma radius4. Resistive loop voltage


1. Vertical position of magnetic axis 2. Bootstrap current3. beta4. Normalized beta


1. Ion temperature on magnetic axis2. Auxiliary heating (ICRH) 3. Electron temperature on magnetic axis4. Resistive loop Volt-seconds


1. Total Volt-seconds2. Plasma Volt-seconds3. External Volt-seconds4. Ion confinement time


1. Ion confinement time2. Volt-seconds of PF (without CS)3. Volt-seconds of CS4. Ohmic heating power


1. Minor radius (95%)2. Upper elongation (95%)3. Down elongation (95%)4. Elongation (95%)


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


1. Z-coordinate of X-point2. Current in upper passive plate3. Current in lower passive plate4. R-coordinate of X-point

Flat-top (profiles - 1)


Flat-top (profiles –2 )


Flat-top (profiles –3)


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 workFuture 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

operational scenario of ktm dokuka v.n., khayrutdinov r.r. triniti, russia

Documents

plasma ramp

plasma position

plasma density

plasma current current

plasma evolution

plasma instability

total plasma currents

plasma boundary transition