2024-09-10T14:18:05Z
https://repo.qst.go.jp/oai
oai:repo.qst.go.jp:00085640
2023-05-15T17:36:27Z
1
Representation and modeling of charged particle distributions in tokamaks
Bierwage, Andreas
1033448
Fitzgerald, Michael
1033449
Lauber, Philipp
1033450
Salewski, Mirko
1033451
Kazakov, Yevgen
1033452
Žiga, Štancar
1033453
Bierwage, Andreas
1033454
Experimental diagnostics, analysis tools and simulations represent particle distributions in various forms and coordinates. Algorithms to manage these data are needed on platforms like the ITER Integrated Modeling & Analysis Suite (IMAS), performing tasks such as archiving, modeling, conversion and visualization. A method that accomplishes some of the required tasks for distributions of charged particles with arbitrarily large magnetic drifts in axisymmetric tokamak geometry is described here. Given a magnetic configuration, we first construct a database of guiding center orbits, which serves as a basis for representing particle distributions. The orbit database contains the geometric information needed to perform conversions between arbitrary coordinates, modeling tasks, and resonance analyses. Using that database, an imported or newly modeled distribution is mapped to an exact equilibrium, where the dimensionality is reduced to three constants of motion (CoM). The orbit weight is uniquely given when the input is a true distribution: one that measures the number of physical particles per unit of phase space volume. Less ideal inputs, such as distributions estimated without drifts, or models of particle sources, can also be processed. As an application example, we reconstruct the drift-induced features of a distribution of fusion-born alpha particles in a large tokamak, given only a birth profile, which is not a function of the alpha’s CoM. Repeated back-and-forth transformations between CoM space and energy-pitch-cylinder coordinates are performed for verification and as a proof of principle for IMAS.
journal article
Elsevier
2022-02
Computer Physics Communications
275
108305
0010-4655
https://repo.qst.go.jp/records/85640
eng
10.1016/j.cpc.2022.108305
https://www.sciencedirect.com/science/article/pii/S0010465522000236
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