The Research & Review seminars are intended to:
During PPPL On-Site Curtailment Zoom information will be posted along with the meeting announcement below.
Some presentations have been recorded. If the title is orange, click it and begin to watch.
Stability, or instability, is the central theme for plasma physics. In this talk, I will prove and demonstrate using examples from plasma physics the following facts.
1) The only route for a conservative system to become unstable is through the resonance between a positive-action mode and a negative-action mode.
It is not the “free energy” that drives the system unstable.
2) For most stable systems, stability is a consequence of being symplectic (or G-unitary for complex systems), instead of the existence of
dissipation or damping.
3) Dissipation can destabilize a system by breaking the symplectic (or G-unitary) condition.
4) By not preserving the symplecticity, numerical and analytical models for conservative systems diverge quickly from the true dynamics.
 R. Zhang, H. Qin et al., arxiv:1801.01676 (2018)
 R. Zhang, H. Qin et al., Phys. Plasmas 23, 072111 (2016)
 J. Xiao, H. Qin & J. Liu, Plasma Sci. Tech. 20, 110501 (2018)
*Things in this context include conservative systems, numerical and analytical models thereof.
The DOE workshop on “Integrated Simulations” has identified a number of critical aspects in the integration of physics modules in a whole device model for tokamak simulations. Challenge includes not only the need for physics description, but also a need for hardware infrastructure, software integration and difficulties in integrating multi-scale coupling.
This seminar summarizes the conclusions from the integrated simulations workshop on MHD stability and disruptions, boundary physics and core transport, as well as a need for research on innovative workflows that enable the integration.