A. Matsubara

D.V. Kalinina

Experimental Group LHD

H. Funaba

K. Sato

M. Goto

N. Tamura

R. Ishizaki

S. Kato

S. Muto

S. Sudo

V.Yu. Sergeev

National Institute for Fusion Science (NIFS-Repository)

References:Fig. 1. The dependence of(a) the decay time ofn Ka emission and(b) the maximal intensity ofthe emissions ofFe Ka, Cr Ka and TiKa measured by PHAat Port 2.0 on the line-averaged electron...+ (8).•NB port-through power... (b)-6MW ./.... /Fe Ka • .' • Ti Ka(Intrinsi<;T II .. (Tracer)i." A,,.... It··... .CrKex, (Intrinsic) "IIl5 12 .' .' • •:1 ; poweri= 6'0 42 •I__:::icO'01°·4E°0 2 3 4 5 6 7n (1019m-3)8_bar# O.8Omm shell dia, w/o atracerLHD# 36912 Estlma18d electron density 2 '¥HP(CaIOJlated) (closed diamond,(open circle), 1.5 <?...... c E1(Measured i ...wi1h PMT)" _ J:S,.• 0.51) SOOo, S.: Plasma Phys. Control. Fusion 44, (2002) 1292) Tamura, N. et al: Plasma Phys. Con1rol Fusion 45, (2003) 273) Tamura, N. et at.: Proc. 30lh EPS Conf. Controlled FusionPlasma Phys. (2003) P-1.59 (St Petersburg, Russia).o 01.691 1.6914 1.6918 1.6922 1.6926Time (8)Fig. 2. An example of the temporal evolution of the estimatedelectron density (closed circle) and the Balmer beta lire intensity(closed diamond), which is calculated from the fitted Lorentziancurve, in the TESPEL ablation cloud. The solid line indicates theBalmer alpha line emission from the ablation cloud (solid line)measured with the photo-multiplier.the fast kinetic mode. In LHD #36912, the electron density, whichis derived from the line width of the Balmer beta due to the S1mXbroadening, in the ablation cloud ofTESPEL, which has a diameterof 0.8 mm and no tracer, increased up to 1.3 x Ion m-3• Thequestion of whether the deduced elec1ron density from the linebroadening observed in the ablation cloud reflects the maximumelectron density in that region or not is discussed with the hydrogenice pellet case. The result derived from the discussion indicates thatthe measured width ofthe line broadening in the pellet cloud doesnot always show the maximum electron density in that region.§ 44. Recent Experimental Results fromTracer Encapsulated Solid PelletInjection on LHDIn order to promote impurity particle transport studies, atraeer-encapsulated solid pellet (TESPEL) has been develctledTESPEL is a double-layered impurity pellet, which consists ofpolystyrene polymer (-CH (CJIs) CHr) as an outer shell (typically,0.3-0.9 nun $) and tracer particles as an inner core (typically, 0.2rom size). TESPEL injection has been implemented for variousimportant studies, such as for heat transport and high-energyparticle transport, as well as for impurity transport study on theLarge Helical Device (LHD) [1].As an important matter fmmd from the experimental resultsrelated to the impurity transport so fur obtained by the TESPELinjection, in the higher density case (11eJm = 3.5 x 1019 m·\ theinward convection is required to account for the experimental resultob1ained, even with the inward convection velocity at the plasmaedge less than 1mis, which is rather different from the case with thelower density (11eJm = 1.8 x 1019 m-) [2]. In the last LHD campaign,the TESPEL experiment wi1h the electron density over 3.5x 1019 ni3 has been performed As seen in Fig. l(a), the Ti tracerimpurity deposited inside the LHD plasma (p = 0.7-0.8) was stillaccwnulated even with neJm =5.6 x 1019 m-3• On the other hand, atthat density, the intrinsic impurities, such as Fe and Cr, coming outfrom the vacuwn vessel wall (p > 1.0) were di1fused away from thecore plasma. This experimental result indicates that the pumpingout mechanism of the impurities should exist on the periphery ofthe plasma (p > 0.7-0.8). In the next LHD campaign, in order toinvestigate the pumping out mechanism of the impuritiesquantitatively, the TESPEL injection aimed at the tracer depositingoutside the periphery ofthe plasmawill be tried.In the study of the high-energy particle by means of the pelletcharge exchange diagnostic, which consists ofa TESPEL injectionand a natural diamond detector-based energy analyzer, in order toestimate the space-resolved energy spectnun of plasma ionsquantitatively, it is important to know the electron density, whichchanges with the TESPEL traveling across the plasma, in theTESPEL ablation cloud In order to evaluate the electron density inthe lwninous cloud surrounding the TESPEL injected into the LHDplasma, measurements of Hydrogen Balmer beta line broadeningare made [3], since the outer shell of TESPEL is made ofpolystyrene. The highly time-resolved spectra of light emissionsfrom the TESPEL ablation cloud were measured with aspectrometer coupled with an intensified CCO, which operated inTamura, N., Kalinina, D.V., Sudo, S., Kato, S.,Sergeev, V.Yu., Muto, S., Sato, K., Funaba, H.,Matsubara, A., Goto, M., Ishizaki, R.,LHD Experimental Group48

Recent Experimental Results from Tracer Encapsulated Solid Pellet Injection on LHD

Recent Experimental Results from Tracer Encapsulated Solid Pellet Injection on LHD

Abstract

Similar works

Full text

Available Versions

National Institute for Fusion Science (NIFS-Repository)