Zhouqian, Wan baonian and spectroscopy team Proposal of the impurity particle transport in LHCD and the impurity behaviors before and after Boronization Zhouqian, Wan baonian and spectroscopy team

Motivation HT-7 Impurities play an important role on plasma behavior in tokamak. radiation losses, plasma resistivity, the plasma particle and energy balance, the MHD instabilities and disruption. A full understanding of impurity particle transport behavior plays an important role in the thermonuclear fusion research and the achievement of controlled fusion power. An impurity transport code, on the assumption of a cylindrical symmetry, can derive the diffusion coefficient Dk(r), the convection velocity Wk(r) and the total flux of the impurity ions k through simulating the experiment results of the emissivity of line emission from ionized light impurities k(r).

spectroscopic diagnostics system Impurity particle transport in LHCD Outline HT-7 spectroscopic diagnostics system Impurity particle transport in LHCD Impurity behaviors before and after Boronization Impurity particle transport before and after Boronization

Visible multi-channel spectroscopic measurement system (VIS) HT-7 1- plasma; 2, 4, 5- lens; 3- 35m fibers; 6- 1m monochromator; 7- 2m fibers; 8- photomultipliers; 9- amplifiers Spectrum respone : 3700 Å ~ 6500 Å Space resolution : 1.5 cm Time response : 20 kHz Monochromators : grating : 1180 g/mm blazing wavelengths : 3900 Å response of spectrum : 2000 Å ~ 7000 Å relative aperture : F/6.7 Visible multi-channel spectroscopic measurement system (VIS) is used to obtain the brightness distribution of line emission from ionized light impurities. It has been calibrated absolutely by using a standard tungsten.

Ultraviolet and visible spectroscopic measurement system (UV) HT-7 The observed spatial range :  27cm Spectrum respone : 2000 Å ~ 7000 Å Space resolution : <1 cm 1- plasma; 2- a rotating hexahedral mirror; 3- lens; 4- fibers; 5, 6- monochromator; 7- photomultipliers; 8- amplifiers; 9- He-Ne laser; 10- photodiode detector. Monochromators : grating : 1200 g/mm blazing wavelengths : 2500 Å and 3000 Å respectively wavelength resolution : 0.2nm (entrance slit 200 µm, exit slit 200 µm) response of spectrum : 2000 Å ~ 7000 Å relative aperture : F/6.7

Ultraviolet and visible spectroscopic measurement system (UV) HT-7 Minimal time resolution : 3ms (at 3000 rev min-1) The system with a rotating hexahedral mirror for space-time resolved measurements in the ultraviolet and visible spectroscopic range can provide the brightness profiles of the light impurity line emission. The plasma was scanned in the vertical direction and two different emission lines of light impurities can be observed in one discharge simultaneously. A center monitoring system (HN) is used to provide the information of spacial position during every scan period . The increase side of the pulse of HN signal corresponds to the center of plasma.

the system of visible multi-channel bremsstrahlung measurement (VB) HT-7 The interference filters : 0= 5780 Å Δ= 20 Å Space resolution : 1.6 cm Time response : 20 kHz 1- plasma; 2,4,6- lens; 3- 35m fibers; 5- interference filters; 7- photomultipliers; 8- amplifiers The profile of the effective ionic charge of the plasma Zeff(r) has been obtained from the system of visible multi-channel bremsstrahlung measurement (VB). It has been calibrated absolutely by using a standard tungsten.

the emissivity from UV HT-7 CV (2271 Å) OV (2781 Å)

the emissivity from VIS and the Zeff from VB HT-7

spectroscopic diagnostics system Impurity particle transport in LHCD Outline HT-7 spectroscopic diagnostics system Impurity particle transport in LHCD Impurity behaviors before and after Boronization Impurity particle transport before and after Boronization

Impurity particle transport simulation HT-7 ne( r) from a five-channel FIR HCN laser interferometer Te( r) from a compact soft X-ray PHA or ECE Te( rp) and ne( rp) from the Langmuir probe Ti( 0) from NPA H/(H+D) from OSMA Ip , Bt , etc

Impurity transport model HT-7 A set of coupled differential equations: The flux of the impurity ions: The neutral impurity density: Dk the diffusion coefficient Wk the convection velocity Both neoclassical and anomalous transport have been considered. The assumption of a cylindrical symmetry. D and W are the anomalous factors. the process of ionization, radiative recombination and dielectronic recombination have been taken into account. Assumed that the neutral impurities flow into the plasma at thermal velocity V0, and the density n0( r) decreases rapidly through ionization as the impurities penetrate the plasma.

Simulation HT-7 The results show the agreement of the experimental result and the simulation result.

Simulation results ( I ) HT-7 With the increase of ne, the diffusion coefficient Dk(r) and the convection velocity Wk(r) decreased. The improved confinement of impurity particles at higher electron densities in ohmic discharge was clearly shown in the results.

Simulation results ( II ) HT-7

The improvement of the particle confinment in LHCD has been observed HT-7

the impurity particle transport in LHCD HT-7 Ne scanning: ne=1, 2, 3 PLHCD =300kw; =0º; Bt=1.9T; Ip=120kA; LHCD Power PLHCD and phase  scanning: PLHCD =100kw, 200kw, 300kw, 400kw =0º, 90º, 180º, 270º at per PLHCD Bt=1.9T; Ip=120kA;

spectroscopic diagnostics system Impurity particle transport in LHCD Outline HT-7 spectroscopic diagnostics system Impurity particle transport in LHCD Impurity behaviors before and after Boronization Impurity particle transport before and after Boronization

the impurity behaviors before and after Boronization HT-7 The impurity level are decreased after boronization.

HT-7

The reduction of impurity influx HT-7

C、O明显变弱; Hb无明显变化; Ha 明显变强 HT-7

the impurity behaviors before and after Boronization HT-7 Spectroscopic diagnostics: OII; OV 单道 OSMA2 VIS for CIII VB for Zeff Ha

spectroscopic diagnostics system Impurity particle transport in LHCD Outline HT-7 spectroscopic diagnostics system Impurity particle transport in LHCD Impurity behaviors before and after Boronization Impurity particle transport before and after Boronization

* WAN Bao-Nian, ZHAO Yan-Pin, LI Jian-Gang, et al The improved confinement both for particle and energy is observed in full operation parameters. HT-7 * WAN Bao-Nian, ZHAO Yan-Pin, LI Jian-Gang, et al 2002 Plasma Science & Technology 4 1375

the impurity particle confinement before and after Boronization ?? HT-7 OH discharge before and after boronization: Bt=2T; Ip=100kA, 150kA; Ne=1, 2, 3;