Plasma Physics Colloquium
Friday,
February 17, 2017
2:00 PM - 3:00 PM
Matt Landreman
Assistant Research Scientist, Institute for Research in Electronics & Applied Physics, University of Maryland, College Park
Title: "An improved current potential method for fast computation of stellarator coil shapes"
Assistant Research Scientist, Institute for Research in Electronics & Applied Physics, University of Maryland, College Park
Title: "An improved current potential method for fast computation of stellarator coil shapes"
Abstract: Several methods for computing stellarator coil shapes are compared, including the classical NESCOIL procedure (Merkel 1987 Nucl. Fusion 27 867), its generalization using truncated singular value decomposition, and a Tikhonov regularization approach we call REGCOIL in which the squared current density is included in the objective function. Considering W7-X and NCSX geometries, and for any desired level of regularization, we nd the REGCOIL approach simultaneously achieves lower surface-averaged and maximum values of both current density (on the coil winding surface) and normal magnetic field (on the desired plasma surface). This approach therefore can simultaneously improve the free-boundary reconstruction of the target plasma shape while substantially increasing the minimum distances between coils, preventing collisions between coils while improving access for ports and maintenance. The REGCOIL method also allows finer control over the level of regularization, it preserves convexity to ensure the local optimum found is the global optimum, and it eliminates two pathologies of NESCOIL: the resulting coil shapes become independent of the arbitrary choice of angles used to parameterize the coil surface, and the resulting coil shapes converge rather than diverge as Fourier resolution is increased. We therefore contend that REGCOIL should be used instead of NESCOIL for applications in which a fast and robust method for coil calculation is needed, such as when targeting coil complexity in fixed- boundary plasma optimization, or for scoping new stellarator geometries.
LOCATION:
← BACK TO EVENTS
- Morningside
- Lecture
- Engineering
- Alumni
- Faculty
- Postdocs
- Prospective Students
- Public
- Staff
- Students
Date Navigation Widget
Getting to Columbia
Other Calendars
- Alumni Events
- Barnard College
- Columbia Business School
- Columbia College
- Committee on Global Thought
- Heyman Center
- Jewish Theological Seminary
- Miller Theatre
- School of Engineering & Applied Science
- School of Social Work
- Teachers College
Guests With Disabilities
- Columbia University makes every effort to accommodate individuals with disabilities. Please notify us if you need any assistance by contacting the event’s point person. Alternatively, the Office of Disability Services can be reached at 212.854.2388 and [email protected]. Thank you.