Ghizzo APS new

Study of nonlinear kinetic effects in Stimulated Raman Scattering using semi-Lagrangian Vlasov codes: 

Study of nonlinear kinetic effects in Stimulated Raman Scattering using semi-Lagrangian Vlasov codes Alain Ghizzo1, P. Bertrand1, T.W. Johnston2, M. Albrecht-Marc1,T. Reveillé1 1. LPMIA, CNRS-UMR7040, Université Henri Poincaré, Nancy, BP 239, F-54506 Vandoeuvre, France 2. I.N.R.S. Energie et Matériaux, Varennes, Québec Alain.Ghizzo@lpmi.uhp-nancy.fr

Topics: 

Topics Vlasov plasmas Vlasov codes and PIC codes Application I: Resonant wave particle interaction Application II: SRS-B in optical mixing Conclusions

Topics: 

Topics Vlasov plasmas Vlasov codes and PIC codes Application I: Resonant wave particle interaction Application II: SRS-B in optical mixing Conclusions

Introduction: 

Introduction . Vlasov models have long been used to study collisionless plasmas. Vlasov codes: powerful tool for studying in details the particle dynamics due to very fine resolution in phase space. Questions for applications: Need for a kinetic model? PIC or Vlasov simulation?

Vlasov plasmas: collective effects: 

Vlasov plasmas: collective effects

Topics: 

Topics Vlasov plasmas Vlasov codes and PIC codes Application I: Resonant wave particle interaction Application II: SRS-B in optical mixing Conclusions

Comparison PIC-Vlasov (1): 

Comparison PIC-Vlasov (1)

Comparison PIC-Vlasov (2): 

Comparison PIC-Vlasov (2)

Comparison PIC-Vlasov (3): 

Comparison PIC-Vlasov (3) Prefer PIC Prefer Vlasov

Topics: 

Topics Vlasov plasmas Vlasov codes and PIC codes Application I: Resonant wave particle interaction Application II: SRS-B in optical mixing Conclusions

Stimulated Raman Scattering: 

Stimulated Raman Scattering

SRS : 3 mode coupling: 

SRS : 3 mode coupling

Three mode coupling : a fluid description: 

Three mode coupling : a fluid description

Three mode coupling : a fluid description: 

Three mode coupling : a fluid description

Three mode coupling : a fluid description: 

Three mode coupling : a fluid description

Time evolution: pump + scattered: 

Time evolution: pump + scattered Check the fluid predictions against a fully kinetic Vlasov simulation

Time evolution : pump + plasma: 

Time evolution : pump + plasma Poor Conservation !

Phase space portraits (1): 

Phase space portraits (1)

Phase space portraits (2): 

Phase space portraits (2)

Phase space portraits (3): 

Phase space portraits (3)

Accounting for « non fluid » particles: 

Accounting for « non fluid » particles

Topics: 

Topics Vlasov plasmas Vlasov codes and PIC codes Application I: Resonant wave particle interaction Application II: SRS-B in optical mixing Conclusions

SRS-B in the « kinetic » regime (1): 

SRS-B in the « kinetic » regime (1) SRS-B reflectivity presents a bursting behavior Nonlinear frequency shift - G.J. Morales and T.M. O’Neil, PRL 28, 417 (1972) -

SRS-B in the « kinetic » regime (2): 

SRS-B in the « kinetic » regime (2)

Topics: 

Topics Vlasov plasmas Vlasov codes and PIC codes Application I: Resonant wave particle interaction Application II: SRS-B in optical mixing Conclusions

Conclusions: 

Conclusions Vlasov codes as compared to PIC codes lack of numerical noise good resolution in phase space provided the dimension of velocity space is as low as possible. Kinetic effects in plasmas allow more phenomena than are found using only fluid theory with « ad hoc » kinetic damping.