Laboratory astrophysics with magnetized laser...

Laboratory astrophysics with magnetizedlaser-produced plasmas

Andrea Ciardi

LERMAObservatoire de Paris and Université Pierre et Marie Curie, CNRS UMR 8112MAGNETIZED

ACCRETION COLUMNS

[email protected]

Collaborators & Acknowledgements

B. Khiar, L. Nicolas (LERMA, Obs. Paris & UPMC, France)

J. Fuchs, T. Vinci, B. Albertazzi, D. Higginson, M. Nakatsutsumami, Z. Burkley, S. N. Chen, L.Romagnani, C. Riconda, R. Riquier (LULI, Ecole Polytechnique, France)

J. Beard, J. Billette, O. Portugall (LNCMI, France)

R. Bonito, S. Orlando (Univ. Palermo, Italy), H. Pepin (INRS-EMT, Canada), S. Pikuz (JIHT,Russia), K. Naughton (QUB, UK), A. Soloviev (IAP, Russia), R. Smets (LPP, France)

T. E. Cowan, F. Kroll, H-P. Schlenvoight (Tech. University and HZDR, Germany)

A. Frank, M. Huarte-Espinosa (Univ. Rochester, USA)

Ackwnoledgements. Work was partly funded by the LABEX Plas@Par and the ANR blancSILAMPA.

MFU V (2015) [email protected] 2 / 23

Plasmas and high-power lasers

I Laser intensity 1012 − 1014 W cm−2(long-pulse ∼ 1 ns) Plasma evolution over few ×10 ns Plasma volume 1 cm3

I Plasma material: (CxHy)n, Al, Cu, ....I Temperatures ∼ (1− 3)× 106 KI Particle density ∼ 1018 − 1021 cm−3

I Velocities ∼ 100− 1000 km s−1

I Mach number (fast-magnetosonic) � 1I Reynolds number ∼ 105

I Magnetic Reynolds number ∼ 100− 1000I Plasma-β � 1I Radiatively cooled flows: τcool/τhydro � 1


Magnetic fields in laser-produced plasmas

I Self-generated fields (Biermannbattery)

∂B∂t =

ce∇×

(1ne∇Pe

) Mega Gauss magnetic fields Limited in spatial (few ×100µm)

and temporal extent (ns) to laserspot, asymmetric shocks, ...

I Externally applied magnetic fields Fraction of a MG Long-lasting (hundreds of ns) and

large-scale (cm3) Gao et al 2015


Experiments on the ELFI laser at LULI

Magnetic field generation and laserI Split Helmholtz coil (LNCMI Toulouse)I Pulsed-power: 32 kJ, 25 kV, 250 kA

HZDR Helmholtz DresdenReossendorf)

I Bmax ' 40T = 0.4MG homogeneousover the plasma extent

Overview of the talkI Jet collimationI Magnetized accretion columns and

shocksI Ion/ion streaming instabilities

Albertazzi+ Rev.Sci.Inst. 2013MFU V (2015) [email protected] 5 / 23

Modelling tools

Laboratory simulations

I GORGON (Ciardi+2007) 3D MHD + high-energy density (HED) physicsI DUED (Atzeni+2004) Lagrangian hydrodynamics 2D + HED physicsI FLASH (Tzeferacos+2014) 3D MHD + HED physics

HED physics: Laser energy absorption, two-temperatures (ion and electron),multi-group radiation transport, tabulated EOS, thermal conduction, ...

Astrophysical simulations

I RAMSES (Teyssier+2002) 3D MHDI PLUTO (Mignone+2005) 3D MHDI HECKLE (Smets+2007) 3D hydbrid (PIC ions + fluid electrons)


JET COLLIMATION


Poloidal collimation in astrophysics

I Shape supernova remnants (Kulsrud etal 1965)




I Collimation of stellar winds into jets(Kwan and Tademaru 1988)

I Simulations (Stone et al 1992) showedthe formation of elongated outflowfrom an isotropic wind.











I Potential role of poloidal collimationcoupled to MHD launching (Matt et al2003)


Magnetized laser-driven plasmas to studyastrophysical jets

Estimates of B and tcoll

I Spherical expansion halted whenρv 2 ∼ B2

0/8πI Collimation radius

Rcoll ∼ 0.8(EK/B2

0)1/3 cm

I Bulk kinetic energy EK = f ELwith f ∼ 0.2− 0.5 a

I Collimation time-scale

tcoll ∼ Rcoll/vexp

wherevexp(cm/s) ∼ 4.6× 107I1/3λ2/3 b

aMeyer & Thiell 1984bTabak et al 1994


Magnetized laser-driven plasmas to studyastrophysical jets

Estimates of B and tcoll

I Spherical expansion halted whenρv 2 ∼ B2

0/8πI Collimation radius

Rcoll ∼ 0.8(EK/B2

0)1/3 cm

I Bulk kinetic energy EK = f ELwith f ∼ 0.2− 0.5 a

I Collimation time-scale

tcoll ∼ Rcoll/vexp

wherevexp(cm/s) ∼ 4.6× 107I1/3λ2/3 b

aMeyer & Thiell 1984bTabak et al 1994

Nominal laser parameters:EL = 50 − 500 J ; τL = 1 ns; λ = 1.064µm;

φ = 750µmNeed B0 & 0.1 MG “steady” over t � 10 ns


3D MHD simulations: time-evolutionI ∼ 1014 W cm−2 and B0 ∼ 0.2MG

Ciardi+2013MFU V (2015) [email protected] 10 / 23

Flow instabilitiesRayleigh-Taylor type filamentation instability1

Configuration similar to a θ-pinchI Growth rate

γ ∼√

gkθ

kθ = m/Rjet

g ∼ v 2/RC

I Growth time-scale is short

τI ∼τcoll√

m∼ few ns

1Kleev & Velikovich 1990MFU V (2015) [email protected] 11 / 23

First evidence of cm-long magnetized jets in laserexperiments

Albertazzi+ Science 2014MFU V (2015) [email protected] 12 / 23

Poloidal collimation of a stellar/disk winds

I Stellar/disk wind from a source 8 AU indiameter

I Magnetic field is uniform or hourglass shapedI Wind parameters “typical” of young stellar

objects Full opening angle α = 60◦ − 180◦

Mass ejection rates:MW ∼ 10−8 − 10−7 M� yr−1

Wind velocity:vw ∼ 100 − 400 km s−1(with 5%perturbation)

Magnetic field: B ∼ 3 − 40mG T = 104 K

I Interstellar gas has uniform density andnegligible thermal pressure

I 3D MHD + cooling done with RAMSES(Teyssier 2002, Fromang et al 2006) Adaptive mesh: up to 5 levels and

maximum resolution of 0.25 AU


Uniform magnetic field, isotropic wind

B = 10 mG; Mw = 10−7 M� yr−1 ; vw ∼ 200 km s-1

mass density log10 ρ (g cm-3)


Effects of changing the strength of the initialmagnetic fieldHour-glass magnetic field from Cao & Spruit 1997

Mw = 5 × 10−8 M� yr−1; vw ∼ 200 km s-1; α = 120◦

mass density log10 ρ (g cm-3)

Origin of stationary soft x-ray sourcesSee Gudel et al; Schneider et al; Bonito et al

I Observation of stationary (several years)x-ray emission D ∼ 30− 140 AU from

I LX ∼ 1028 − 1029 erg s-1

I TX ∼ 3− 7× 106 K


Origin of stationary soft x-ray sourcesSee Gudel et al; Schneider et al; Bonito et al

I Observation of stationary (several years)x-ray emission D ∼ 30− 140 AU from

I LX ∼ 1028 − 1029 erg s-1

I TX ∼ 3− 7× 106 K

I Emission measure EM(T ) =∫

nenHdV more x-ray emitting material for low B

I LX depends (among other things) on B


MAGNETIZED ACCRETION COLUMNS

Magnetized accretion columns in YSO

I Material from the accretion discis channeled along magneticfield lines and falls onto the star.




I We are interested in studying inthe laboratory the stability anddynamics of magnetizedaccretion columns Numerical simulations are

generally limited to 2Daxisymmetry

Influence of back-flowingplasma on the reverse shock

Orlando+2010




I We are interested in studying inthe laboratory the stability anddynamics of magnetizedaccretion columns Numerical simulations are

generally limited to 2Daxisymmetry

Influence of back-flowingplasma on the reverse shock


ION STREAMING INSTABILITY

Streaming instability

I Energetic ions streaming along magnetic filed lines with vbulk � VA can leadto the rapid non-linear growth of magnetic field perturbations (Alfven andmagnetosonic).

I Important in transport/confinement low-energy (< 100 MeV) cosmic rays diffusive shock acceleration pick-up ions in the solar wind and presence of diffuse ions in the foreshock

e.g. see reviews by Gary et al 1991 et Zweibel 2013


Streaming instability: experiments

Experiments planned for 2016 on the ELFIElaserI nbeam/nback ∼ 0.001− 0.1I vbeam/VA ∼ 10− 100I Diagnostics

electron density and temperaturefluctuations (interferometry andThomson scattering), ion energyspectrum (Thomson parabola),magnetic field (Faraday rotation), ...

Toncian+2006


Outlook

Coupling of laser-produced plasmas with “strong” magnetic fields can help toclarify the physics of (some) astrophysical systems/process.

Many more astrophysically relevant experiments done over all the world on laserand z-pinch machines.

I See the high-energy density laboratory astrophysics conference website forsome ideas hedla2014.sciencesconf.org Plasma physics / Stellar explosions / Magnetized HED laboratory astrophysics

/ Astrophysical disks, jets, and outflows / Stellar, solar and nuclearastrophysics / Computations in HED physics / Radiative hydrodynamics /Warm dense matter

Observational constraints: a small selection


Date post:	21-May-2020
Category:	Documents
Upload:	others
View:	1 times
Download:	0 times

Laboratory astrophysics with magnetized laser...

Documents