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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 e Goal of the work The DINA code capabilities Formulation of the problem Examples of simulations Conclusions Future work. Goal of the work. Modeling of different discharge scenarios for KTM tokamak

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OPERATIONAL SCENARIO of KTM Dokuka V.N., Khayrutdinov R.R. TRINITI, Russia

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  1. OPERATIONAL SCENARIO of KTMDokuka 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

  2. Goal of the 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 control • Disruptions simulation • X-point position control

  3. 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.

  4. 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

  5. Theoretical and numerical analysis of plasma-physical processes at KTM • Breakdown and plasma initiation • Ramp-up • Flat-top • Plasma Vertical Stability • Disruptions • Shot down

  6. Scheme of discharge scenario at KTM Bt = 1 T IP = 0.75 MA Paux = 5 MW Plasma current flat-top Plasma current shut-down Plasma current ramp-up Auxiliary heating Toroidal magnetic field creation Plasma current initiation Vacuum creation, gas puff

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

  8. 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

  9. Techniques used for creation PF scenario • 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

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

  11. 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

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

  13. An initial set of programmed PF currents

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

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

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

  17. Plasma parameters on the stage of ramp up

  18. 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

  19. Plasma parameters on flat top

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

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

  22. Evolution of plasma parameters 1 • Plasma current • Poloidal beta • Minor radius • Horizontal magnetic axis

  23. Evolution of plasma parameters 2 • Averaged electron density • Elongation • Internal inductance • Vacuum vessel current

  24. Evolution of plasma parameters 3 • Averaged ion temperature • Safety factor on magnetic axis • Safety factor on the plasma boundary • Averaged electron temperature

  25. Evolution of plasma parameters 4 • Electron density in the plasma center • Global confinement time • Major plasma radius • Resistive loop voltage

  26. Evolution of plasma parameters 5 • Vertical position of magnetic axis • Bootstrap current • beta • Normalized beta

  27. Evolution of plasma parameters 6 • Ion temperature on magnetic axis • Auxiliary heating (ICRH) • Electron temperature on magnetic axis • Resistive loop Volt-seconds

  28. Evolution of plasma parameters 7 • Total Volt-seconds • Plasma Volt-seconds • External Volt-seconds • Ion confinement time

  29. Evolution of plasma parameters 8 • Ion confinement time • Volt-seconds of PF (without CS) • Volt-seconds of CS • Ohmic heating power

  30. Evolution of plasma parameters 9 • Minor radius (95%) • Upper elongation (95%) • Down elongation (95%) • Elongation (95%)

  31. Evolution of plasma parameters 10 • Upper triangularity (95%) • Down triangularity (95%) • Triangularity (95%) • Horizontal position of magnetic axis

  32. Evolution of plasma parameters 11 • Z-coordinate of X-point • Current in upper passive plate • Current in lower passive plate • R-coordinate of X-point

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

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

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

  36. Volt-seconds balance

  37. 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

  38. 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

  39. Simulink model for R-Z control of KTM

  40. The results of simulation of R-Z control for KTM

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