14th iea rfp workshop – padova, april 26th-28th 2010 rfx-mod thermal measurement system: a...
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114th IEA RFP Workshop – Padova, April 26th-28th 2010
RFX-mod thermal measurement system:a possible diagnostic for plasma-wall interaction
M. Dalla Palma1, E. Sartori2
and the RFX-mod Team
1 Consorzio RFX, EURATOM-ENEA Association, corso Stati Uniti 4, I-35127 Padova, Italy2 Università degli Studi di Padova, Italy
Padova, April 28th 2010
2
14th IEA RFP Workshop – Padova, April 26th-28th 2010
Outline
Description of the RFX-mod thermal measurement system
Purpose of the activity:correlation of plasma-wall interaction with thermal measurements
Approach:
1. development of models for thermal characterization of tiles, vacuum vessel and toroidal support structure
2. development of an integrated thermal model
3. inference of plasma parametersfrom thermal experimental measurements, by using the integrated model
4. comparison of the deduced plasma parameters with that ones obtained from other measurements
RFX past analyses
314th IEA RFP Workshop – Padova, April 26th-28th 2010
Thermal measurements on RFX-mod
Plasma-Wall Interaction (PWI) diagnostic by correlating thermal fluxes to the thermocouple (TC) measurements
The thermal measurement system is important for:
Machine diagnostic to control:
– the achievement of the operational limits due to high heat fluxes on the graphite tiles
– irregular temperature due to localized plasma-wall interaction
– temperature increase due to Joule effect in the coils
414th IEA RFP Workshop – Padova, April 26th-28th 2010
Thermocouples set on RFX-mod
Plasma
8 TCs on the first wall - Integrated System of Internal Sensors (ISIS) [20÷400°C]
228 total TCs on the vacuum vessel rings [20÷200°C]
16 TCs on vacuum vessel sheet [20÷200°C]
16 TCs on the copper shell [20÷180°C]
16 TCs on the copper shell clamping bands [20÷180°C]
16 TCs on the toroidal support structure [20÷60°C]
8 TCs on 4 saddle coils [20÷100°C]
19 TCs on 3 magnetizing coils [20÷200°C]
514th IEA RFP Workshop – Padova, April 26th-28th 2010
TCs layout on the external surface of the vacuum vessel
θ = 0°
θ = 0°
22.5°
67.5°
112.5°
157.5°
202.5°
247.5°
292.5°
337.5°
φ = 0°ring 1
φ = 355°ring 72
40° 65° 100° 125°25° 180° 320°270°
θ = 0° External equator, θ = 90° Top
GAP on copper shell (112.5°)
GAP on copper shell (292.5°)
TCs on vacuum vessel rings
TCs on vacuum vessel sheet
TCs for comparison with other sensors or diagnostics
TCs on dense sectors
614th IEA RFP Workshop – Padova, April 26th-28th 2010
Planned activity
Correlation of plasma wall interaction (PWI) with thermal measurements, in particular:
• quantification of power density and energy of the uniform distributed and localized PWI
• localization of the un-uniform and/or wall-locked PWI
Approach:
1. development of models for thermal characterization of tiles, vacuum vessel and toroidal support structureby numerical analyses and validation with experimental measurements
2. development of an integrated thermal modelsimulating heat fluxes from the first wall to the whole toroidal support structure
3. inference of plasma parametersfrom thermal experimental measurements, by using the integrated model
4. comparison of the deduced plasma parameters with that ones obtained from magnetic measurements and possibly with IR camera measurements of the tile surface temperature.
714th IEA RFP Workshop – Padova, April 26th-28th 2010
1. Thermal characterization
TilesPlasma
814th IEA RFP Workshop – Padova, April 26th-28th 2010
1. Thermal characterization
TilesPlasma Rings
914th IEA RFP Workshop – Padova, April 26th-28th 2010
1. Thermal characterization
TilesPlasma
Vessel sheet
Copper shell
Toroidal structure
Rings
Shell clamping bands
1014th IEA RFP Workshop – Padova, April 26th-28th 2010
1. Thermal characterization
TilesPlasmaToroidal structure
Rings
The model parameters are optimized considering:
Effective shape and dimensions of tiles, vacuum vessel and toroidal support structure
Thermo-physics parameters of materials
Thermal contact resistance at the interfaces
Heat transfer mechanisms among interfaced structures
1114th IEA RFP Workshop – Padova, April 26th-28th 2010
1. Thermal characterization
TilesPlasmaToroidal structure
Rings
PWI: PWI: radiation and radiation and
convectionconvection
1214th IEA RFP Workshop – Padova, April 26th-28th 2010
1. Thermal characterization
TilesPlasmaToroidal structure
Rings
Thermal Thermal conduction conduction
through through fixing keysfixing keys
1314th IEA RFP Workshop – Padova, April 26th-28th 2010
1. Thermal characterization
TilesPlasmaToroidal structure
Rings
Th. Conduction through vessel
supports+
Convection (chimney effect)
and radiation
Th. Conduction through vessel
supports+
Convection (chimney effect)
and radiation
PWI: PWI: radiation and radiation and convectionconvection
Thermal Thermal conduction conduction
through through fixing keysfixing keys
1414th IEA RFP Workshop – Padova, April 26th-28th 2010
2. Development of an integrated thermal model
TilesPlasmaToroidal structure
Rings
Th. Conduction through vessel
supports+
Convection (chimney effect)
and radiation
Th. Conduction through vessel
supports+
Convection (chimney effect)
and radiation
PWI: PWI: radiation and radiation and convectionconvection
Th. Th. conduction conduction
through through fixing keysfixing keys
Thermal results
Model validation: comparison with
experimental measurements
1514th IEA RFP Workshop – Padova, April 26th-28th 2010
3. Inference of plasma parameters
TilesToroidal structure
Rings
Th. Conduction through vessel
supports+
Convection (chimney effect)
and radiation
Th. Conduction through vessel
supports+
Convection (chimney effect)
and radiation
PWI: PWI: radiation and radiation and convectionconvection
Th. Th. conduction conduction
through through fixing keysfixing keys
Integrated modelIntegrated model
Thermal measurements
Plasma
1614th IEA RFP Workshop – Padova, April 26th-28th 2010
Integrated Integrated ModelModel
3. Inference of plasma parameters
Thermalmeasurements
Plasma
• quantification of the power density and energy of uniform distributed and localized PWI
• localization of the un-uniform and/or wall-locked PWI
4. Validation with magnetic and IR camera measurements
mode lockingregion
1714th IEA RFP Workshop – Padova, April 26th-28th 2010
Past thermal analyses
First wall temperatures [°C]
Thermal analyses were carried out with the old RFX finite element model simulating experimental sessions of old RFX
New thermal analyses are ongoing with finite element models simulating the thermal behaviour of the RFX-mod.
The thermal results are compared with the RFX-mod thermal measurements.
Vacuum vessel temperatures [°C]
1814th IEA RFP Workshop – Padova, April 26th-28th 2010
RFX-mod thermal measurement system:a possible diagnostic for plasma-wall interaction
M. Dalla Palma1, E. Sartori2
and the RFX-mod Team
1 Consorzio RFX, EURATOM-ENEA Association, corso Stati Uniti 4, I-35127 Padova, Italy2 Università degli Studi di Padova, Italy
Padova, April 28th 2010