[Jlab-seminars] Fwd: Plasma Theory/Nonlinear Dynamics Seminar: "Symplectic and Variational Integration" - John M. Finn

[Mary Fox]

-------- Forwarded Message --------
Subject: 	Plasma Theory/Nonlinear Dynamics Seminar: "Symplectic and 
Variational Integration" - John M. Finn
Date: 	Thu, 5 Apr 2018 18:43:46 +0000
From: 	Wilkinson, Ellie V <evwilk at wm.edu>
To: 	physics2017 at physics.wm.edu <physics2017 at physics.wm.edu>
CC: 	undergrads2017 at physics.wm.edu <undergrads2017 at physics.wm.edu>



*_Plasma Theory/Nonlinear Dynamics Seminar_*

Wednesday, April 11, 2018

12:00 PM

Small Hall, Room 235

*John M. Finn *[Host: E. Tracy]**

Tibbar Plasma Technologies; Los Alamos National Laboratory (retired)

* Title of Talk: **“Symplectic and Variational Integration”***

**




*Abstract:* In the context of canonical Hamiltonian systems, variational 
integrators provide an alternative way of deriving symplectic 
integrators. Variational integrators can be formed by discretizing the 
action based on a conventional configuration space Lagrangian, or 
alternately based on discretizing a phase space action principle. A 
phase space action principle leads to an ODE system which is degenerate, 
producing the first order canonical Hamiltonian equations of motion. A 
haphazard discretization can lead to discrete equations that are higher 
order in time, allowing for parasitic modes, which can be unstable. More 
careful discretizations can lead to a system which is properly 
degenerate. I present a review of these concepts and extend them to two 
noncanonical systems of interest in plasma physics, namely magnetic 
field lines and the guiding center equations of motion. A major outcome 
of this work is that for the discrete system to be properly degenerate, 
there is a straightforward test, based on the discrete form of the Hessian.

*Speaker Bio:*John M. Finn received his PhD from the University of 
Maryland in 1974. He worked at the Naval Research Laboratory, at the 
University of Maryland and, since 1993, at Los ALamos National 
Laboratory. He retired from LANL in 2016 to form the startup Tibbar 
Plasma Technologies, Inc. His research has been in plasma physics, for 
application to magnetic fusion as well as solar and astrophysical 
problems, with a focus on the application of Dynamical Systems to plasmas.


Everyone is invited.

******

*Eleonor V. Wilkinson*

Administrative & Office Specialist

The College of William & Mary-Physics
Small Hall, Room 123
300 Ukrop Way
Williamsburg, VA 23185

Telephone: 757-221-3503

Fax: 757-221-3540

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mailman.jlab.org/pipermail/jlab-seminars/attachments/20180405/c50820dd/attachment-0001.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image003.jpg
Type: image/jpeg
Size: 11849 bytes
Desc: not available
URL: <https://mailman.jlab.org/pipermail/jlab-seminars/attachments/20180405/c50820dd/attachment-0001.jpg>