Department of Physics John Anderson Research Colloquia

Wednesday's at 3.00pm (unless otherwise stated) 

Colloquia will usually be held in JA3.14
John Anderson Building 
107 Rottenrow, Glasgow

Coffee and Tea served at 4.00 pm.

All Welcome

Coordinated with the Colloquia at the Department of Physics and Astronomy of the University of Glasgow. (They may have donuts but we have free chocolate covered biscuits and coffee!)

Colloquia Schedule 2018-2019

Semester I

  • 27/08/18 - Jerome V Moloney (College of Optical Sciences, University of Arizona) *
  • 03/10/18 - Alessandra Giunta (STFC RAL Space)
  • 17/10/18 - Celso Grebogi (Institute for Complex Systems and Mathematical Biology, King’s College, University of Aberdeen)

Semester II

  • TBA

* Note: Outside of regular schedule.

Physics of Ultrashort Long-Wave Infrared TeraWatt Pulse Atmospheric Propagation and Interactions

Jerome V Moloney (College of Optical Sciences, University of Arizona) 27 August 2018, JA3.14, 11am

We predict that new physics paradigms emerge when long wave high power, high energy ultrashort pulses are propagated in the atmosphere. Specifically, optical carrier shock waves and many-body excitation induced dephasing emerge as key players at progressively longer wavelengths. Mathematically, the canonical description of propagation is described by a full field resolved modified Kadomtsev – Petviashili (mKP) equation. The latter encompasses two important singularities, namely blow-up or critical self-focusing and optical carrier self-steepening – the former is also described by nonlinear envelope equations. While ionization induced defocusing and losses tend to dominate at near-IR wavelengths, dispersive waves generated by shocks tend to limit the growth in filament intensity at longer wavelengths in the mid-IR.

From the Sun to controlled fusion: plasma diagnostics and spectroscopic techniques

Alessandra Giunta (STFC RAL Space) 3 October 2018, JA3.14, 3pm

The emission of photons and all spectral lines have encoded information to diagnose the physical and chemical status of the emitting source, carrying the signature of the underlying plasma parameters.

This approach is appropriate not only in an astrophysical context, but also for laboratory fusion plasmas. Atomic physics provides the link that enables the observed spectra to be interpreted in terms of the properties of the source from which they arise, whether they originate in an experiment on Earth, such as a laser or tokamak device, or in an astronomical object, ranging from the Sun and stars to planetary nebulae and interstellar medium.

The increasing capabilities of the current and new space-borne instrumentation (e.g. Interface Region Imaging Spectrometer, Solar Orbiter, Parker Solar Probe) and controlled fusion devices (e.g. Mega Ampère Spherical Tokamak Super-X upgrade divertor, International Thermonuclear Experimental Reactor, DEMOnstration Power Station), require atomic modelling and the derived spectroscopic techniques to be regularly revised and upgraded.

The present work will strongly exploit this interdisciplinary link between laboratory and astrophysics plasma environments. Atomic data requirements and their accuracy will be discussed, concentrating on the applications to the analysis of the solar upper atmosphere emission and the investigation of controlled fusion plasmas in a tokamak divertor. An example of the exploitation of a common methodology for the detection and assessment of non-equilibrium processes will be described. This will show that the derived atomic data allow equivalent prediction in non-stationary transport regimes and dynamic conditions of both the solar atmosphere and tokamak divertor.

Chaos and Complexity

Celso Grebogi (Institute for Complex Systems and Mathematical Biology, King’s College, University of Aberdeen) 17 October 2018, JA3.14, 3pm

Many simple nonlinear deterministic systems can behave in an apparently unpredictable and chaotic manner. This realisation has broad implications for many fields of science. Some basic concepts and properties in the field of chaotic dynamics of dissipative systems will be reviewed in this talk, including strange nonchaotic attractors, chaos-induced intermittency, and fractal basin boundaries. I will use some of these properties in application topics, including the control of chaos in the brain. I will then go a step further by arguing that a complex system is made up of many states that are interrelated in a complicated manner. The ability of a complex system to access those different states, combined with its sensitivity, offers great flexibility in manipulating the system’s dynamics to select a desired behaviour. Another important issue is the question of mathematical modelling of chaotic and complex systems. Mathematical modellers of such systems need to understand and take seriously the question of their own limitations.

  • Chaos, strange attractors, and fractal basin boundaries in nonlinear dynamics, C. Grebogi, E. Ott, and J. A. Yorke, Science 238, 632 (1987)
  • Strange attractors that are nonchaotic, C. Grebogi, E. Ott, S. Pelikan, and J. A. Yorke, Physica D 13, 261 (1984)
  • Controlling complexity, L. Poon and C. Grebogi, Phys. Rev. Lett. 75, 4023 (1995)
  • Controlling Chaotic Dynamical Systems, C. Grebogi and Y. C. Lai, Systems Control Lett. 31, 307 (1997)
  • Modelling of deterministic chaotic systems, Y.-C. Lai and C. Grebogi, Phys. Rev. Lett. 82, 4803 (1999)
  • Data Based Identification and Prediction of Nonlinear and Complex Dynamical Systems, W.-X. Wang, Y.-C. Lai, and C. Grebogi, Phys. Reports. 644, 1-76 (2016)
  • Relativistic quantum chaos – An emergent interdisciplinary field, Y.-C. Lai, H.-Y Xu, L. Huang, and C. Grebogi, AIP CHAOS 28, 052101 (2018)