Fyzika tokamaků1: Úvod, opakování1 Tokamak Physics Jan Mlynář 8. Heating and current drive Neutral beam heating and current drive,... to be continued

Neutral Beam Injection: principle Ion source Neutral beam Electricity -> other form (kinetic energy of particles) Transport to plasma (outside part) Neutraliser Magnetic filter Beam duct (inside part) Accellerator IonisationThermalisation

NBI Principle, in more detail I E Day

Size matters – ITER beamline vs Torus I E Day

Evolution from Present Status - ITER

Tokamak Physics6 Neutral beam heating 8: Heating and current drive =

Tokamak Physics7 Neutral beam heating 8: Heating and current drive

Tokamak Physics8 Neutral beam heating 8: Heating and current drive

Tokamak Physics9 Beam slowing 8: Heating and current drive

Tokamak Physics10 Distribution function 8: Heating and current drive

Tokamak Physics11 Beam current drive 8: Heating and current drive

Wave heating Electricity -> other form (electromagnetic oscillations) Transport to plasma (outside part) transmission lines antenna (inside part) waves Thermalisation Antenna Wave to particles Resonance zone R

Classification of waves phase velocity –fast –slow direction of propagation –k parallel to B 0 : according to polarisation (with respect to B 0, in other fields of science –e.g. optics- wrt propagation direction) right -> direction of rotation of electrons left -> direction of rotation of ions –k perpendicular to B 0 ordinary: E 1 // B 0 extraordinary: E 1 perp to B 0

Tokamak Physics14 Wave Heating 8: Heating and current drive Review of Plasma Waves

Tokamak Physics15 Wave Heating 8: Heating and current drive Dielectric Tensor

Tokamak Physics16 Wave Heating 8: Heating and current drive Classification of waves

Tokamak Physics17 Wave Heating 8: Heating and current drive Resonances, Cut-offs

Tokamak Physics18 Wave Heating 8: Heating and current drive Resonances, Cut-offs

Tokamak Physics19 Wave Heating 8: Heating and current drive Energy flow

Tokamak Physics20 Wave Heating: Ray tracing 8: Heating and current drive

Tokamak Physics21 Wave Heating: Ray tracing 8: Heating and current drive ASDEX-U

Tokamak Physics22 Wave Heating: Ray tracing 8: Heating and current drive Mode conversion Boundary conditions

Tokamak Physics23 Wave Heating: CMA diagram 8: Heating and current drive In each region, the topological form of the phase velocity remain unchanged. Fast wave is outside (the wave front in vacuum which would always be a circle) slow wave is inside. E.g. in the top left region (high B, low n) the X/L wave is slow, the O/R wave is fast (X and O have k || B, L and R have k ┴ B)

Tokamak Physics24 Ion Cyclotron Heating 8: Heating and current drive fast wave~ tens of MHz Plasma edge cutoff below heating on harmonic frequencies on minorities (e.g. on H in D plasmas) Resonant layer is vertical at Heating on harmonics  energies often higher than E c  relaxation is mostly due to heating of electrons

Tokamak Physics25 Ion Cyclotron Heating 8: Heating and current drive

Tokamak Physics26 Ion Cyclotron Heating 8: Heating and current drive Heating on minorities: Decreases with increasing concentration, however, new “ion-ion” hybrid resonance emerges. May result in IBW (Ion Bernstein Wave)  can drive electrons Disadvantage: strongly sensitive on minority concentration ICRH advantages: Economic, powerful, important ion heating disadvantages: high E, problems with reflected power (ELMs), (“coupling of waves to plasma”, in particular problems with ELMs), non-directional.

Plasma edge – evanescent region (cutoff below ) i.e. “waves tunnels through” The antenna produces a wide spectrum  wide spectrum of fast electrons due to the Landau damping  current drive Tokamak Physics27 Lower Hybrid Resonance 8: Heating and current drive Slow wave at a small angle to B ~ GHz  long path to the resonant region  Landau damping along the path turns out to be more important than LH itself Reminder: The current drive would not exist if distribution of velocities of plasma particles were flat. However, Maxwellian distribution is not flat, which means wave can locally flatten the distribution in the direction of the wave propagation.

Tokamak Physics28 Lower Hybrid Resonance 8: Heating and current drive

Mode converter Equally split the RF power in 3 in the poloidal direction 1 input & 3 outputs WR-229 Conversion efficiency: % Return Loss: -20.5dB J. Hilairet

LH - Wave Propagation Depends on n e and B Antenna structure

Tokamak Physics31 Electron Cyclotron Resonance 8: Heating and current drive Advantages : no evanescent region highly directional highest achievable power density Disadvantages:acts only on electrons expensive new technology (less reliable) Highly directional  profile control e.g. suppression of NTMs (mg. islands)

Tokamak Physics32 Electron Cyclotron Resonance 8: Heating and current drive

Tokamak Physics33 Electron Cyclotron Resonance 8: Heating and current drive

Tokamak Physics34 Electron Cyclotron Resonance 8: Heating and current drive Current Drive (ECCD) Other applications of ECR: 1)Fisch – Boozer directional increase of decreases 2)Ohkawa increase of pushes passing particles into the trapped region (opposite direction to the Fisch - Boozer)  lower momentum loss - plasma heating - current profile control for advanced regimes - transport studies via modulated ECRH - plasma start-up assistance - wall conditioning (ITER)

Tokamak Physics35 Bulk and Tail Current Drive 8: Heating and current drive

Tokamak Physics36 ITER ECR system 8: Heating and current drive 24 x 1 MW, 170 GHz gyrotrons 3 x 1 MW, 120 GHz gyrotrons for SUA wave guide switch to … equatorial or upper launcher

Tokamak Physics37 ITER ECR Upper Port 8: Heating and current drive 3 ports with 8 beams in two rows Main function: NTM (and sawtooth) control Front steering –In vertical direction to scan radial deposition –Well focussed for optimised localization at q=3/2 and 2