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Publié par | Thesee |
Nombre de lectures | 18 |
Langue | English |
Poids de l'ouvrage | 2 Mo |
Extrait
CzechTechnicalUniversityinPrague
FacultyofNuclearSciencesandPhysicalEngineering
DepartmentofPhysicalElectronics
&
Universite´ Bordeaux1
´ ´EcoleDoctoraledesSciencesPhysiquesetdel’Ingenieur
CentreLasersIntensesetApplications
IonAccelerationinSmall sizeTargets
byUltra intenseShortLaserPulses
(SimulationandTheory)
AdissertationthesissubmittedtotheCTUinPragueand
Universite´ Bordeaux1inpartialfulfillmentoftherequirements
forthedegreeofDoctorofPhilosophy(PhD)
Author: JanPsikalˇ
ˇSupervisors: Jir´ıLimpouch,VladimirTikhonchuk
Dateofsubmission: 16.10.2009Declaration
This dissertation is the result of my own work, except where explicit reference is made to
the work of others, and has not been submitted for another qualification to this or any other
university.
Prague,16thOctober2009 JanPsikalˇ
2Acknowledgements
Due to the fact that my doctoral studies were spent between the Department of Physi
cal Electronics at the Faculty of Nuclear Sciences and Physical Engineering of the Czech
Technical University in Prague and Centre Lasers Intenses et Applications in the campus of
UniversityofBordeaux1,manypeopledeservemythanks.
Firstandforemost,Imustthankmytwoexcellentsupervisors-Prof. JiriLimpouchfrom
PragueandProf. VladimirTikhonchukfromBordeaux. Istronglyappreciatetheirguidance,
encouragement,patiencewithme,andtheirhumanity. Theyhavegivenmeenoughfreedom
tomakemyownmistakesandlearnfromthembutatthesameplacetheyhavegentlypushed
meforwardintherightdirection.
Among first people, I also have to express my profound gratitude to my family - my
beloved parents and my brother. During the course of my PhD study, we lived in a very
difficult time for us. My father became seriously ill and he left us after 16 months of our
fightagainsthisdisease. IamgratefultoVladimirwhokindlytoleratemyfrequentholidays
intheCzechRepublicwithmyfamilyatthisdifficulttimeandtomanyothersfortheirhelp.
I have written this thesis mainly to my beloved dad who strongly supported my study and
education. Unfortunately, he cannot be present at the end of my study which have taken
really enough time (in fact, I started at school 21 years ago), but he is still with me in my
heart.
During my PhD study, I have met many excellent physicists and kind people. I would
liketothankDr. SargisTer AvetisyanfromtheQueen’sUniversityofBelfast,Prof. Alexan
der Andreev from Research Institute for Laser Physics in St. Petersburg, Prof. Shigeo
Kawata from Utsunomiya University in Japan, and Dr. Julien Fuchs from Laboratoire pour
l’UtilisationdesLasersIntenses(LULI)inPalaiseauclosetoParisforinterestingandfruitful
cooperation.
IappreciatemyyoungcolleaguesfromPragueandBordeaux,whohavegivenmeimpor-
tant advice and who have kindly helped me. I express my thanks to Ondˇrej Klimo, Martin
Masek,ˇ DanielKl´ır,ArnaudDebayle,AfeintouSangam,RolandDuclous,CyrilRegan,Can
diceMezel,MarionLafon,andothers.
Finally,supportbythefollowingprojectsisalsogratefullyacknowledged:
Ministry of Education, Youth and Sports of the Czech Republic, projects No. LC528
andNo. MSM6840770022
CzechScienceFoundation,projectsNo. 202/08/H057andNo. 202/06/0801
CzechTechnicalUniversityinPrague,projectsNo. CTU0708014,No. CTU0813214,
andNo. CTU0916514
Grantoffrenchgovernment-”BoursedeDoctoratenco tutelle”
I forgot to name plenty of kind people, but I must cut the list somewhere. Excuse me and
thankyouall.
3Contents
1 Introduction 7
1.1 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.2 Aimsandnewcontributionsofthework . . . . . . . . . . . . . . . . . . . 9
1.3 ThesisStructure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2 Laser plasmaAcceleration 12
2.1 Basictheoreticalbackground . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.1.1 Threeapproachestoplasmaphysics . . . . . . . . . . . . . . . . . 14
2.2 Motionofasingleparticleinrelativisticlaserfield . . . . . . . . . . . . . 15
2.2.1 Ponderomotiveforce . . . . . . . . . . . . . . . . . . . . . . . . . 18
2.3 Interactionofultrashortintenselaserpulsewithplasma . . . . . . . . . . . 19
2.3.1 Basiclaserbeamparameters . . . . . . . . . . . . . . . . . . . . . 19
2.3.2 Propagationofahigh intensitylaserbeaminplasma . . . . . . . . 20
2.3.3 Laserprepulse,preplasmaformation,andrarefactionwave . . . . . 21
2.4 Electronaccelerationmechanismsatthecriticalsurface . . . . . . . . . . . 22
2.4.1 Hotelectronpopulation. . . . . . . . . . . . . . . . . . . . . . . . 23
2.4.2 Brunelvacuumheating . . . . . . . . . . . . . . . . . . . . . . . . 23
2.4.3 jB heating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
2.4.4 Angulardistributionoffastelectrons. . . . . . . . . . . . . . . . . 25
2.4.5 Propagationofhotelectronsinsidethetarget . . . . . . . . . . . . 26
2.4.6 Guidingofhotelectronsalongthesurfaceandtheiracceleration . . 28
2.4.7 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
2.5 Ionaccelerationinsolidtargets . . . . . . . . . . . . . . . . . . . . . . . . 32
2.5.1 Ionaccelerationatthetargetfrontside . . . . . . . . . . . . . . . . 33
2.5.2 Targetnormalsheathaccelerationmechanism . . . . . . . . . . . . 34
2.5.3 Multipleionspecies . . . . . . . . . . . . . . . . . . . . . . . . . 39
2.5.4 Enhancementofionenergyduetoreducedtargetthickness . . . . . 41
2.5.5 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
2.6 Ionaccelerationinclusters . . . . . . . . . . . . . . . . . . . . . . . . . . 44
2.6.1 Coulombexplosioninsmallclusters . . . . . . . . . . . . . . . . . 44
2.6.2 Iondynamicsinlargerclusters . . . . . . . . . . . . . . . . . . . . 45
2.6.3 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
43 Particle in CellSimulations 47
3.1 VlasovequationandaPICcode . . . . . . . . . . . . . . . . . . . . . . . 47
3.2 Basicschemeofparticle in cellcodes . . . . . . . . . . . . . . . . . . . . 49
3.3 Algorithmsofourtwo dimensionalPICcode . . . . . . . . . . . . . . . . 50
3.3.1 Maxwellequations . . . . . . . . . . . . . . . . . . . . . . . . . . 50
3.3.2 Chargeconservationmethods . . . . . . . . . . . . . . . . . . . . 51
3.3.3 Particlesolvers . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
3.3.4 Interpolationoffields . . . . . . . . . . . . . . . . . . . . . . . . . 56
3.4 Boundaryconditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
3.4.1 Boundaryconditionsforparticles . . . . . . . . . . . . . . . . . . 56
3.4.2forfields . . . . . . . . . . . . . . . . . . . . 57
3.5 ParallelizationofthePICcode . . . . . . . . . . . . . . . . . . . . . . . . 58
3.6 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
4 InteractionofanIntenseLaserPulsewithMass limitedTargets 60
4.1 Interactionofextremelyshortultraintenselaserpulsewithhydrogenplasma 60
4.1.1 Interactionofthepulsewithacylindricaltarget . . . . . . . . . . . 61
4.1.2 Enhancedionaccelerationduetoreductionofthesheathwidth . . . 62
4.1.3 Spectraofemittedradiationfromplanarandsphericaltargets . . . 66
4.1.4 Scaling of hot electron temperature and maximum proton energy
withthelaserintensity . . . . . . . . . . . . . . . . . . . . . . . . 67
4.2 Ionaccelerationbyfemtosecondpulsesinmultispeciestargets . . . . . . . 68
4.2.1 Mutualinteractionoftwoionspecies . . . . . . . . . . . . . . . . 69
4.2.2 Conversionefficiencyandinfluenceofinitialdensityprofile . . . . 73
4.2.3 Angulardivergenceoffastprotons . . . . . . . . . . . . . . . . . . 76
4.3 Enhancedlaser drivenprotonaccelerationfromthinfoilsections . . . . . . 78
4.3.1 Experimentalresults . . . . . . . . . . . . . . . . . . . . . . . . . 79
4.3.2 Ourtheoreticalinterpretationoftheresults . . . . . . . . . . . . . 81
4.4 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
5 Laserprotonaccelerationinawaterspraytarget 87
5.1 Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
5.1.1 Experimentalsetup . . . . . . . . . . . . . . . . . . . . . . . . . . 87
5.1.2results . . . . . . . . . . . . . . . . . . . . . . . . . 88
5.2 Theoreticalanalysisofexperimentalresults . . . . . . . . . . . . . . . . . 90
5.2.1 Generaldiscussion . . . . . . . . . . . . . . . . . . . . . . . . . . 90
5.2.2 Numericalsimulationsofthelaserpulseinteractionwithasubwavelength
sizedwatermicrodroplet . . . . . . . . . . . . . . . . . . . . . . . 92
5.2.3 Energydistributionofacceleratedprotons . . . . . . . . . . . . . . 95
5.3 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
6 Lateralhotelectrontransportandionaccelerationinthinfoils 98
6.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
6.2 Simulationmethodandparameters . . . . . . . . . . . . . . . . . . . . . . 99
6.3 Resultsanddiscussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
56.3.1 Hotelectronguiding . . . . . . . . . . . . . . . . . . . . . . . . . 100
6.3.2 Protonacceleration . . . . . . . . . . . . . . . . . . . . . . . . . . 105
6.3.3 Efficiencyofionacceleration . . . . . . . . . . . . . . . . . . . . 108
6.4 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
7 Conclusions 110
7.1 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
7.2 Perspectives . . . . . . . . . . . .