M3D-C1 Meeting�Nate Ferraro�Feb. 5, 2024

Agenda

• Status update

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• Overview of M3D-C1 activities

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• Reading stellarator output with Fusion-IO

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• Other issues?

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Status

commit b5367d3a66fdc61f191d7b2e165ceff616a37470

Date: Wed Jan 31 17:54:30 2024 -0500

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• PPPL Cluster (m3dc1/devel-centos7): PASSED
• Stellar (m3dc1/devel): PASSED
• Perlmutter CPU (m3dc1/devel-cpu):

adapt FAILED: C1ke files do not match

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• Issues / bugs?
• Andreas raised an issue with mesh boundary tags disappearing during adaptation, but seems not to be a problem after mesh is saved / loaded?

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Overview of M3D-C1 Activities

• ELMs (Kleiner)
• Energetic particles / kinetic MHD / REs (C. Liu, Saxena, Zhao)
• Core MHD in tokamaks (Banerjee, Jardin, D. Liu)
• Disruptions (Clauser, Ferraro, C. Liu, Lyons, Strauss, Zhao)
• Meshing software (Seol, Shephard, Riaz)
• Pellets / impurities (Lyons)
• RMPs (Zhao, Ferraro, Kleiner)
• Solvers (Adams, Chen)
• Stellarators (Ferraro, Hudson, Liu, Saxena, Wright, Zhou)

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Reading M3D-C1 Stellarator Output with Fusion-IO

• Fusion-IO is a library that provides functions for reading data from M3D-C1 and other MHD codes (https://github.com/nferraro/fusion-io)

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• Obviates the need for codes to understand M3D-C1’s output format (which is very complicated) or to perform interpolations.

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• We also don’t want codes to need to know how to translate computational coordinates into physical coordinates
• All Fusion-IO functions require coordinates to be given in either cylindrical (R,φ,Z) or cartesian (X,Y,Z).

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• M3D-C1 stellarator output is in computational (x,φ,z) coordinates that are mapped to physical coordinates with fields R(x,φ,z) and Z(x,φ,z)
• Need the (x,φ,z) coordinates to evaluate the field, but nontrivial to find the (x,φ,z) coordinates associated with the requested (R,φ,Z) coordinates

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Reading M3D-C1 Stellarator Output with Fusion-IO

• To find (x,φ,z) associated with requested (R,φ,Z):
• Precalculate the (R,φ,Z) coordinates of each mesh node (done when mesh is loaded)
• Search through elements to find which element contains the requested R,φ,Z coordinate, and the approximate (x,φ,z) coordinates within that element (using linear interpolation)
• Perform Newton iterations to converge on the exact (x,φ,z) coordinate

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• Fusion-IO also has an interface to return the derivatives of the field (wrt (R,φ,Z)). This is now also implemented for all first- and second- derivatives (as described in Yao’s paper).
• Some higher mixed derivatives like d³/dRdRdφ are not presently available

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Reading M3D-C1 Stellarator Output with Fusion-IO

• Caveats:
• Some M3D-C1 outputs like xmag, zmag, etc. are still in computational coordinates and these are not yet translated to (R,Z) by Fusion-IO;
• Some higher derivatives are not yet implemented

• Bottom line: most tools using Fusion-IO now should now work for M3D-C1 stellarator output without any modification
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Other issues?

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