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Status of Di vertor P lasma S imulator – II ( DiPS -II). 2 nd PMIF Workshop . Sep. 19, 2011 Julich , Germany. H.-J. Woo 1 , K.-S. Chung 1 , S.-J. Park 1 , S.-G. Cho 1 , E.-K. Park 1 , and T. Lho 2 1 Center for Edge Plasma Science, Hanyang University, Seoul 133-791, Korea
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Status of DivertorPlasma Simulator – II (DiPS-II) 2nd PMIF Workshop Sep. 19, 2011 Julich, Germany H.-J. Woo1 , K.-S. Chung1, S.-J. Park1, S.-G. Cho1, E.-K. Park1, and T. Lho2 1Center for Edge Plasma Science, Hanyang University, Seoul 133-791, Korea 2National Fusion Research Institute, Daejeon 305-333, Korea
CONTENTS • Review of DiPS – I • LaB6 Cathode • Concepts and Objects of DiPS – II • Summary and Future Work
DiPS - I • DiPS-I : Schematics LaB6 is located at null magnetic field.
DiPS - I • Typical Magnetic Field of DiPS-I
DiPS – I : Experimental Results • Probe Diagnostics : I-V Characteristics Dimensions of Probe Tip: 0.5 mm (Dia.) and 3 mm (length) vs. Magnetic Field vs. Discharge Current
DiPS – I : Experimental Results • Probe Diagnostics : Electron Temperature (Te) and Plasma Density (np) vs. Magnetic Field vs. Discharge Current Plasma Density : Particle Flux Density Plasma Density : Confinement Effect
DiPS – I : Experimental Results • LIF Diagnostics vs. Magnetic Field Ion Temperature Drift Velocity • Ion temperature and parallel flow velocity are increased versus the magnetic field intensity. • The perpendicular flow velocity remains near zero, since the contributions of E X B and diamagnetic effect are negligible at the plasma center in the magnetized cylindrical plasmas.
DiPS – I : Experimental Results • LIF Diagnostics vs. Discharge Current Ion Temperature Drift Velocity • Ion temperature and parallel flow velocity are increased versus the discharge current.
DiPS – I : Experimental Results • Ion Temperature and Drift Velocity vs. Plasma Density • Magnetic Field Variation → Ion Temperature (Plasma Density + Magnetic Field) • Discharge Current Variation → Ion Temperature (Plasma Density)
LaB6 Cathode for DiPS – I & II • LaB6 Cathode for DiPS – I & II
LaB6 Cathode for Large Plasma Generation • LaB6 Cathode for MP2 – Large Plasma Source
LaB6 Cathode : Heater Temperature Estimation • Heater Temperature Estimation
LaB6 Cathode : Heater Temperature Estimation • Heater Temperature Estimation B. Noyes, Jr., Phys. Rev. 24, 190 (1924).
DiPS - II • DiPS – II has been developed to overcome the weaknesses of DiPS – I and improve the machine performance. • Weaknesses of DiPS – I: • Neutral Pressure Control – only two section separated by differential pumping. • Low Particle Flux – limited plasma current. • Small Plasma Size : Core Plasma Size ~ 2 cm • Objective of DiPS-II • Understanding of the Plasma Wall Interaction • Higher Plasma Flow Generation with Magnetic Nozzle Concept. • Characterizations of Attached/Detached Plasmas (Neutral Effects). – Need Highly Differential Pumping • Developments of Diagnostics for KSTAR. • Tests of PFC Materials.
DiPS - II B. Labambard, 21st Transport Taskforce Workshop, Boulder, CO (March 25-28, 2008) .
DiPS - II • Concepts of Magnetic Nozzle – From Helicon Experiments VASIMR Concepts Helicon Plasma Without Ion Heating HELIX and LEIA, West Virginia University X. Sun, Phys. Rev. Lett. 95, 025004 (2005)
DiPS - II • Concepts of Magnetic Nozzle – From Experience of MP2 (NFRI: Dr. LHO) Measurement Position A & B
DiPS - II • Concepts of Magnetic Nozzle – From Experience of MP2 (NFRI: Dr. LHO) High Field Chamber (Position A) : Magnetized 1st Port of Central Cell (Position B) : Un-magnetized
DiPS - II • Concepts of Magnetic Nozzle – From Experience of MP2 (NFRI: Dr. LHO) High Field Chamber (Position A) : Magnetized 1st Port of Central Cell (Position B) : Un-magnetized
DiPS - II Magnetic Nozzle • Schematic Diagram of DiPS-II
DiPS - II • Typical Magnetic Field of DiPS-II
DiPS - II • Construction and Plasma Generation Diagnostics and Material Test Regime First Plasma at Sep. 2010.
DiPS - II • LaB6 Cathode Damage (Melting) at High Current Operation (over 90 A) In diverging field configuration, the LaB6 cathode can be damaged by localized current in light gas operation such as helium (low ion gyro-radius). → Need the Null Field Geometry LaB6 Cathode Melting
DiPS – II : Flow Measurement Results The plasma flow velocity is nearly zero (stationary plasma), which might be due to grounded chamber wall disturbs the ion acceleration.
DiPS – II: TS Diagnostics Horizontal Pixel No. (related to Wavelength) • Install Laser Thomson Scattering for Detached Plasmas & Material Test Vertical Pixel No. (related to Radial Position) TS Sample R = -14 mm R = -10.5 mm R = -7 mm R = - 3.5 mm R = 0 mm R = +3.5 mm R = +7 mm R = +10.5 mm R = +14 mm Blocked Region (Rayleigh Scattering) Mirror & Lens Array
DiPS – II: TS Diagnostics 40 A Discharge with Ar
FUTURE WORK • One will change magnetic nozzle chamber as floating structure (or biased structure), which is now grounding. • One also add the source magnet for cusp magnetic field. • The design is already finished.