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2012-13/
Seminari A.A. 2012-2013
 
 
I Seminari si svolgono il martedì alle 14:30 nell'aula 311 del Dipartimento di Matematica (salvo diversa indicazione)
 
 
Relatore
Titolo
Data
 
 
 
Omar Maj
Max-Planck Inst. für
Plasmaphys. Garching
02 Luglio 2013
(ore 14:00)
 
 
 
Marco Brambilla
Max-Planck Inst. für
Plasmaphys. Garching
11 Giugno 2013
 
 
Abstract
ritorna
In the first part of this talk we point out that the linear electrodynamics of hot plasmas must be formulated in a different way compared to ordinary dielectrics or conductors. The difference is due to the fact that in a hot plasma collisions are so rare that the mean free path of charged particles are much longer than the typical wavelengths of all modes of plasma electromagnetic oscillations. As a consequence, the plasma is dispersive both in time and space. In an infinite homogeneos plasma space dispersion is reflected in the fact that the conductivity tensor depends on the wavevector of each plane wave considered. Since plane waves, on the other hand, are not eigenmodes of real, non-uniform plasmas, space dispersion makes it very difficult to solve the linearized Vlasov equation to obtain the constitutive relation, i.e. the linear relation between high frequency current and field in the plasma. In magnetically confined plasmas the particle orbits are multi-periodic. This has suggested (Kaufmann 1972) the use of action-angle variables to solve the problem. This approach is fascinatingly simple and elegant, but the results, if taken literally, lead to predictions which contraddict expectation and experimental evidence. Investigating the reason of these paradoxes is very interesting, since it is a first step to understand how irreversibility arises from a reversible model, and to the construction of a consistent 'closed' theory of linear wave propagation in plasmas. In the second part of the talk we sketch the solution of the linearized Vlasov equation with the spectral method. The integral, non local constitutive relation obtained in this way is very complicated, but physically transparent, and is, therefore, a good starting point for approximations based on clearly formulated assumptions, which lead to wave equations valid for concrete problems, and which can be numerically solved with a reasonable effort. To confirm this, we will finally show a few pictures of wave propagation in tokamaks in the Ion Cyclotron range of frequencies, obtained with the full-wave solver TORIC.
 
 
 
Mustapha Mourragui
Université de Rouen
16 Maggio 2013
(giovedì)
 
 
 
Mustapha Mourragui
Université de Rouen
15 Maggio 2013
(mercoledì)
 
 
 
Bruno Coppi
MIT
14 Maggio 2013
(ore 15:00)
 
 
 
Francesco Califano
Università di Pisa
14 Maggio 2013
(ore 14:00)
 
 
 
Alain Messager
CPT - CNRS
Marseille
Phase transitions in the long range XXZ model
07 Maggio 2013
(ore 15:30)
 
 
 
Carlo Marchioro
Università di Roma
"La Sapienza"
07 Maggio 2013
 
 
 
Milos Zahradnik
Charles University
Prague
30 Aprile 2013
(ore 15:00)
 
 
 
Daniela Grasso
CNR e
Politecnico di Torino
30 Aprile 2013
(ore 14:00)
 
 
 
Yuri Kondratev
Universität Bielefeld
23 Aprile 2013
 
 
 
Israel Michael Sigal
Toronto University
12 Aprile 2013
(venerdì)
 
 
 
Errico Presutti
Università di Roma
"Tor Vergata"
09 Aprile 2013
 
 
 
Giovanni Gallavotti
INFN Roma1 e
Accademia dei Lincei
05 Marzo 2013
 
 
 
Alessandro Pizzo
UC Davis
23 Ottobre 2012
(ore 16:00)
 
 
 
Zhituo Wang
Paris XI - Orsay
26 Settembre 2012
(mercoledì)
 
 
 
Joel Lebowitz
Rutgers University
Three easy (to state) open problems (that have worried me for many years)
24 Settembre 2012
(lunedì 16:00 aula F)
 
 
 
Manuel de Llano
UNAM
21 Settembre 2012
(venerdì)