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Key figures

Key figures

189 people work at LJLL

86 permanent staff

80 researchers and permanent lecturers

6 engineers, technicians and administrative staff

103 non-permanent staff

74 Phd students

15 post-doc and ATER

14 emeritus scholars and external collaborators


January 2022


Stability and interaction with walls for magnetic fusion plasmas


Upcoming seminars  (See events in the agenda)

- Tuesday 21 January 2021 at 11am : Claude Bardos (Université de Paris)

Quasilinear Approximation of the Vlasov Equation



The object of this talk is to report on a joint ongoing program with Nicolas Besse Prof. Observatoire de la Cote d’Azur et Université de Nice.

The quasi linear approximation for solutions of the Vlasov equation is a very popular tool in Plasma Physic cf. [1] which proposes, for the quantity :
q ( ∫f (x, v, t)dx) , (1)
the solution of a parabolic, linear or non linear evolution equation
∂_t q(t, v) − ∇_v (D(q, t ; v)∇_v q) = 0 . (2)

Since the Vlasov equation is a hamiltonian reversible dynamic while (2) is not reversible whenever D(q, t, v) ≠ 0 the problem is subtle. Hence I will do the following things :

1. Give some sufficient conditions, in particular in relation with Landau damping that will imply that D(q, t, v) ≃ 0 .

2. Building on contributions of [3] and coworkers show the validity of the approximation (2) for large time and for a family of convenient randomized solutions.

3. In the spirit of a Chapman Enskog approximation formalize the very classical physicist approach for a short time approximation under analyticity assumptions.


[1] Plasma Physic in the 20th century as told by players. Guest editors.:P. Diamond, U. Frisch and Y. Pomeau. Vol 43 , 4-5, December 2018.

[2] N.A. Krall, A.W. Trivelpiece Principles of plasma physics, McGraw-Hill, 1973.

[3] F. Poupaud, A. Vasseur, Classical and quantum transport in random media, J. Math. Pures Appl. 82 711–748 (2003).



Seminar room 15-16, 3rd floor, room 309

Laboratoire Jacques Louis Lions

Sorbonne Université

4 place jussieu, 75252 Paris FRANCE

You can get easy access to the place with the lift of tower 16, situated on the left when arriving on the campus.mapNouvelle fenêtre




The working group meets on Tuesday at 11:00 a.m. (in principle). All topics concerning mathematical, numerical or physical modelling of magnetic fusion plasmas are possible, with a preference for stability issues and the interaction of the plasma with the edges.

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