Modeling non-axisymmetric radiation during rapid shutdown in DIII-D shell pellet experiments using Emis3D

During rapid shutdown, traditional assumptions of toroidal symmetry can not be used in the radiated power analysis. To remedy this, Emis3D has been developed to provide better estimates of Prad by using a forward modeling “guess and check” approach. Emis3D does this by comparing synthetic observations of 3D radiation structures, observed with the Cherab modeling framework [M. Carr EPS 2017], to experimental measurements from bolometry and determines a best fit through a reduced χ2 statistic. Emis3D has been successfully used to model non-axisymmetric radiation in JET’s shattered pellet injection (SPI) experiments and is currently being used to inform the design of the SPARC disruption mitigation and bolometry systems. The addition of Emis3D to the DIII-D code suite enables detailed radiation analysis for a device that is well posed to address disruption mitigation research. As an initial test case, Emis3D will be used to provide better estimates of Prad for the DIII-D dispersive shell pellet (DSP) injection experiments. These experiments will provide a good test of Emis3D due to the highly localized nature of the impurity source.

Work supported by US DOE under the Science Undergraduate Laboratory Internship (SULI) program and DE-FC02-04ER54698. Work supported by US DOE, Office of Science, Office of Fusion Energy Sciences, under Award DE-SC0014264