Development and simulation of multi-diagnostic Bayesian analysis for 2D inference of divertor plasma characteristics

TY - JOUR

T1 - Development and simulation of multi-diagnostic Bayesian analysis for 2D inference of divertor plasma characteristics

AU - Bowman, Christopher

AU - Harrison, James Robert

AU - Lipschultz, Bruce

AU - Orchard, Simon

AU - Gibson, Kieran

AU - Carr, M

AU - Verhaegh, Kevin

AU - Myatra, Omkar

PY - 2020/2/12

Y1 - 2020/2/12

N2 - We present results of the design, implementation and testing of a Bayesian multi-diagnostic inference system which combines various divertor diagnostics to infer the 2D fields of electron temperature T e, density n e and deuterium neutral density n 0 in the divertor. The system was tested using synthetic diagnostic measurements derived from SOLPS-ITER fluid code predictions of the MAST-U Super-X divertor which include appropriate added noise. Two SOLPS-ITER simulations in different states of detachment, taken from a scan of the nitrogen seeding rate, were used as test-cases. Taken across both test-cases, the median absolute fractional errors in the inferred electron temperature and density estimates were 10.3% and 10.1% respectively. Differences between the inferred fields and the test-cases were well explained by solution uncertainty estimates derived from posterior sampling. This work represents a step toward a larger goal of obtaining a quantitative, 2D description of the divertor plasma state directly from experimental data, which could be used to gain better understanding of divertor physics phenomena.

AB - We present results of the design, implementation and testing of a Bayesian multi-diagnostic inference system which combines various divertor diagnostics to infer the 2D fields of electron temperature T e, density n e and deuterium neutral density n 0 in the divertor. The system was tested using synthetic diagnostic measurements derived from SOLPS-ITER fluid code predictions of the MAST-U Super-X divertor which include appropriate added noise. Two SOLPS-ITER simulations in different states of detachment, taken from a scan of the nitrogen seeding rate, were used as test-cases. Taken across both test-cases, the median absolute fractional errors in the inferred electron temperature and density estimates were 10.3% and 10.1% respectively. Differences between the inferred fields and the test-cases were well explained by solution uncertainty estimates derived from posterior sampling. This work represents a step toward a larger goal of obtaining a quantitative, 2D description of the divertor plasma state directly from experimental data, which could be used to gain better understanding of divertor physics phenomena.

U2 - 10.1088/1361-6587/ab759b

DO - 10.1088/1361-6587/ab759b

M3 - Article

SN - 0741-3335

JO - Plasma Physics and Controlled Fusion

JF - Plasma Physics and Controlled Fusion

ER -