measurement of divertor heat flux at the end-cell of the gamma 10
DESCRIPTION
OS2012/PMIF2012 Aug.28,2012 Tsukuba(Japan). Measurement of divertor heat flux at the end-cell of the GAMMA 10. H. Matsuura a , H. Takeda b , K. Ichimura b , K. Hosoi b , Y. Nakashima b , M. Sakamoto b , M. Shoji c , K. Nagaoka c , T. Imai b - PowerPoint PPT PresentationTRANSCRIPT
Measurement of divertor heat flux at the end-cell of the GAMMA 10
H. Matsuuraa, H. Takedab, K. Ichimurab, K. Hosoib, Y. Nakashimab, M. Sakamotob, M. Shojic, K. Nagaokac, T. Imaib
aRadiation Research Center, Osaka Prefecture University bPlasma Research Center, University of Tsukuba
cNational Institute for Fusion Science
OS2012/PMIF2012Aug.28,2012Tsukuba(Japan)
Contents of my presentation
• Why is plasma heat flux(energy flux) important?
• What is thermal probe and how is it used ?
• What is necessary for GAMMA 10 (or ITER) plasma heat flux measurement?
• What did we do?What have we obtained?
• What is left for future work?
PSI and heat(Energy) flux
• Plasma medicine and biomaterial treatment
• Plasma CVD and etching
• Space vehicles, such as Hayabusa
• Divertor design and ELM control
Plasma heat flux is important in wide PSI field.
New J. Phys. 11 (2009) 115012
Classical thermal probe
Concept of thermal probe ( or solid calorimeter)
q(t)
Heat flux
tTD
=L2/ t
pulse
TC
T(t)
Measurement data
Inverse heat conduction model
tTD
=L2
/ tpulse
Long pulse plasma
Short pulse plasma
L
q(t)
T(t)
T(t)
q(t)
tip material Heat conductivity
Thermal diffusivity
time constant[s] for L=10[mm]
example
[W/mK] [mm2/s]
Cu 400 100 1.0 H-J
Mo 138 54.3 1.8 MAP-II
SUS 16.0 4.07 4.07 ICP/Magnetron
Pylex Glass 1.089 0.686 146 glow
Measurement of heat flux changeHeat flux change due to H-mode, detachment, plug ECH, and so on is more interesting than steady state heat flux or total heat load per a discharge shot.
LHD results( presented at ITC21)
How about heat flux?
What is necessary for determination of q(t) as like in LHD experiment?
• Fitting procedure of measured TC data with response function model with physical causality
• Response function of probe/calorimeter sensor with appropriate modeling
• A small sensor with fast response (small thermal diffusion time) and good SN ratio
Here we assume the infinite slab model with only plasma irradiation boundary.
Heat sink boundary
Heatsink
Kurihara, Kado (OS2006)
qsink=0
GAMMA 10 Calorimeter tip
Comparison of boundary condition
Plasma pulseprobe tip
Red: perfect sink boundary, Blue: perfect isolation boundary,Magenta: infinite boundary
GAMMA10 Calorimeter system
The west end-mirror region, together with the location of the diagnostic equipment installed for this experiment.
Response of the old sensor
• Was Temperature evolution of TC data sufficiently traced?
In FY 2010 experiment, time response of calorimeter sensor was slow, and data recorder also worked slowly.
q ave S c m V T t pulse
Calorimetric estimation
The heat-flux density is evaluated from the difference between the temperature of the calorimeter tip measured just before the discharge and that measured immediately after the discharge.
One division is 16[min], nearly equal shot interval
Improvement of sensor
Old calorimeter New calorimeter
Material copper copper
TC connection from irradiation surface
about 10mm about 2mm
thermal diffusion time about 1[s] about 40[ms]
Thermocouple Type T with sheath Type T without sheath
Response of TC signal
TC signal noiseDuring and just after discharge, there exist large noises in TC signal.They come from RF power, magnetic field induction, ....
Noise at t=400-2000ms is well compensated with no plasma shot data.
Comparison of the response for box heat pulse with two model
Temperature at x=2,6,12[mm] is estimeted with two boundary model.Present (isolation boundary) model reproduces well the TC data.
heat sink boundary model
2MW/m2, 100ms
thermal isolation boundary model
1MW/m2, 150ms
Conclusion(What we did.)
• We develop a new fitting procedure of measured TC data, and demonstrate with LHD probe data.
• We expand response function model to be applicable to small sensors in GAMMA10.
• We construct a new calorimeter sensor and test it in FY2012 experiment.
What is left for future work?
• Determination of the TC noise origin and reduction of it. ( Isolation Amplifier used in Heliotron J experiment may be effective.)
• Cross check of heat flux estimation
• Determination of heat flux evolution with plug ECH or ICRF additional heating
• Diagnostic as a thermal probe (for example, divertor Ti measurement)
This work is partially performed with the support and under the auspices of the NIFS Collaborative Research Program. (NIFS12KUGM071/NIFS12KUHL047)
Thank you for kind attention.
Any questions and comments are welcome.
Sheath heat transmission factor
HDP analysis(H-J)(Presented at ITC18/ITC19)