predictive modelling of plasma rotation (examples from itpa itb database)
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Transport/ITB IPTA Meeting, St Petersburg, 8-12 April 2003
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Predictive Modelling of Plasma Rotation (examples from ITPA ITB database)
V.V. Parail1T. Tala2, A. Becoulet3, G. Corrigan1,X. Garbet3, D. Heading1, X. Litaudon3, P.I. Strand4 and J. Weiland4
1UKAEA Fusion Association, Culham, UK; 2Association Euratom-Tekes, Finland; 3Association Euratom-CEA, Cadarache, France; 4Chalmers University,
Gothenburg, Sweden
• Selection of shots;• Transport models used in simulation• Comparative role of plasma rotation and negative/zero magnetic shear in ITB formation;• Conclusions and future plans
Transport/ITB IPTA Meeting, St Petersburg, 8-12 April 2003
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Selection of shots Three pairs of plasmas with ITB from JET, JT-60U
and DIII-D (each pair has one shot with and one without negative shear) were used to simulate plasma rotation;
Discharges from JET and DIII-D have tangential NBI injection, which provides adequate torque to generate strong toroidal rotation;
JT-60U uses quasi-perpendicular injection so that toroidal rotation is controlled mainly by neo-classical effects;
Actually JT-60U shots give very good complimentary information about plasma rotation.
Transport/ITB IPTA Meeting, St Petersburg, 8-12 April 2003
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Transport models (1)
• JETTO model (Bohm/gyroBohm)
alneogyroeITG
BEBohmee Cs
,1, 1.0
ie
ieD
neoigyroi
ITG
BE1Bohmii Cs10
,, .
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Transport/ITB IPTA Meeting, St Petersburg, 8-12 April 2003
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Transport models (2)
• Hahm-Burrell formulation of the shearing rate was used in simulations:
RB1
BvBvenTn
BRB
i
ii2
BE)(
Transport/ITB IPTA Meeting, St Petersburg, 8-12 April 2003
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Transport models (3)• Full implementation of Weiland model with off-diagonal elements was used as a second transport model;• Both JETTO and Weiland models were complemented by the full matrix of the neo-classical transport coefficients from
NCLASS;• Weiland model uses the same Hahm-Burrell formulation of the shearing rate;• Same assumption was used for anomalous viscosity:
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Transport/ITB IPTA Meeting, St Petersburg, 8-12 April 2003
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Results of the modelling (JET)
Transport/ITB IPTA Meeting, St Petersburg, 8-12 April 2003
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Results of the modelling (JET)
Legend:
- - - Experiment
__ JETTO, C3=0.9
__ JETTO, C3=1.2;
__ Weiland, normal;
__ “-” Vtorx5;
__ “-” ExBx3
Transport/ITB IPTA Meeting, St Petersburg, 8-12 April 2003
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Results of the modelling (JET)
Transport/ITB IPTA Meeting, St Petersburg, 8-12 April 2003
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Results of the modelling (JET)
Transport/ITB IPTA Meeting, St Petersburg, 8-12 April 2003
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Results of the modelling (JET)
Legend:
- - - Experiment
__ JETTO, C3=0.5
__ JETTO, C3=1.5;
__ Weiland, normal;
__ “-” Vtorx5;
__ “-” ExBx5
Transport/ITB IPTA Meeting, St Petersburg, 8-12 April 2003
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Results of the modelling (JET)
Transport/ITB IPTA Meeting, St Petersburg, 8-12 April 2003
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Results of the modelling (JT-60U)
Transport/ITB IPTA Meeting, St Petersburg, 8-12 April 2003
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Results of the modelling (JT-60U)
Legend:
- - - Experiment
__ JETTO, C3=1.2
__ Weiland, normal;
__ “-” Vtorx3;
__ “-” ExBx10
Transport/ITB IPTA Meeting, St Petersburg, 8-12 April 2003
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Results of the modelling (JT-60U)
Transport/ITB IPTA Meeting, St Petersburg, 8-12 April 2003
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Results of the modelling (JT-60U)
Transport/ITB IPTA Meeting, St Petersburg, 8-12 April 2003
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Results of the modelling (JT-60U)
Transport/ITB IPTA Meeting, St Petersburg, 8-12 April 2003
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Results of the modelling (JT-60U)
Legend:
- - - Experiment
__ JETTO, C3=0.5
__ JETTO, C3=1.2;
__ Weiland, normal;
__ “-” Vtor;
__ “-” ExBx10
Transport/ITB IPTA Meeting, St Petersburg, 8-12 April 2003
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Results of the modelling (JT-60U)
Transport/ITB IPTA Meeting, St Petersburg, 8-12 April 2003
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Results of the modelling (DIII-D)
Transport/ITB IPTA Meeting, St Petersburg, 8-12 April 2003
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Results of the modelling (DIII-D)
Legend:
- - - Experiment
__ JETTO, C3=0.5
__ JETTO, C3=1.0;
__ Weiland, normal;
__ “-” ExBx5
Transport/ITB IPTA Meeting, St Petersburg, 8-12 April 2003
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Results of the modelling (DIII-D)
Transport/ITB IPTA Meeting, St Petersburg, 8-12 April 2003
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Conclusions (1)
Bohm/GyroBohm model reproduces ITBs quite reasonably;
Toroidal rotation is reproduced with
Plasma rotation (both toroidal and poloidal) seems to play a role in ITB formation particularly in discharges without negative magnetic shear;
Bohm/gyroBohm modes tends to over-estimate ITB width in discharges with negative magnetic shear;
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Transport/ITB IPTA Meeting, St Petersburg, 8-12 April 2003
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Conclusions (2)
Weiland model reproduces ITBs only if much increased shearing rate (by 3-10 times);
Generally Weiland model reproduces “weak” barrier much better than the “strong” one;
Same conclusion applies with respect to plasma rotation: it is very difficult to reproduce strong barrier;
Although predictive modelling of plasma rotation does add a “degree of freedom” into simulation, generally it affect the result in a predictable way;
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