Andrea MACCHICNR/INO, PisaandDipartimento di Fisica “Enrico Fermi”, Università di Pisa

www.df.unipi.it/~macchi

Plasma Physics C: Noninear Plasma Processes and Applications

commons.wikimedia.org/wiki/File:Plasma_lamp_touching.jpg

There's a large variety of Plasmas ...

[Da: T.Killian, Science 316 (2007) 705]

… and an unifying viewpoint

Essential theoretical description: many-body system , dominated by collective dynamics, in most cases of interest far from thermal equilibrium

General problem: understand the coherent dynamics and self-organization of the system and achieve its control to develop applications.

Such control is complex (and challenging) due to the strongly nonlinear nature of the dynamics.

The course aims to focus on some nonlinear phenomenology and related nonlinear models (the most accessible ones ...) with possible emphasis on those problems of most general relevance because of either broad relevance for plasma physics , crossover interest or as examples of general techniques of nonlinear physics

Main Topic: Intense Laser-Plasma Interactions

Laser-Matter Interactions: Extreme Intensities

Plasma is the “only” state of matter in such fields (laser field largely exceeds atomic field => instantaneous ionization)

“Relativistic” plasmaproduced routinely

a0 << 1

- linear response

- effects of magnetic force are negligibile

a0 >> 1

- nonlinear response

- effects of magnetic force are non-negligibile

Relativistic Domain

Applications 1: electron accelerators

principle: “surfing” of electrons on a longitudinalwave with proper phasevelocity

the ”perfect wave”: “wake” of a laser field

T.Katsouleas, Nature 431, 515 (2004); 444, 688 (2006)

Applications 2: ion accelerators

intense research since 2000 based on several schemes:- expansion of a hot plasma- radiation pressure boost- acceleration by shock waves

Review paper:

A. Macchi et al, Rev. Mod. Phys. 85, 751 (2013)

Applications 3: “relativistic engineering”

Idea: “coherent control” of laser-plasma dynamics (e.g. “moving mirrors”) to create/manipulate EM pulses(atto/zeptosecond pulses, high armonics, ultra-high fields ...)

Applications 4: Nuclear Fusion

Glenzer et al., Science 327 (2010) 1228;

O. A. Hurricane et al, Nature (2014), doi:10.1038/nature13008

First results from Laser-Driven Inertial Confinement Fusion experiments at the National Ignition Facility (USA) (lasers.llnl.gov)show scaling of “hohlraum” heating consistent with reaching ignition (fusion energy = input energy)of D-T pellet

Controlled Fusion: a long story ...

Dr Octopus trying to control his fusion experiment in “Spiderman 2” (2004)©Marvel, Columbia Pictures

Strip image from Amazing Spider-Man, #44 ©Marvel comics

Laboratory Astrophysics

S.V.Bulanov et al, Eur. Phys. J. D 55 (2009) 483

Example of relativistic plasma in “exotic” astrophysical environment:Pulsar Magnetosphere

Idea: create similar conditions on a different spatio-temporal scale in the laboratory

LabAstro examples - I

S.V.Bulanov et al, Eur. Phys. J. D 55 (2009) 483

S.V.Bulanov et al, Eur. Phys. J. D 55 (2009) 483

LabAstro examples - II

Towards QED Plasmas and Ultimate Fields?

Ultrahigh fields open up the possibility to investigate exotic effects: radiation friction, pair plasmas, Unruh effect, QED cascades...

Ultimate frontier: approach the QED Schwinger field

Ecr=m

e

2c3/eħ corresponding to I>1029 W/cm2

Physical meaning: eEcrλ

c=m

ec2 => pairs are created from vacuum

two-fold interest for laser-plasma interactions: - use the plasma as an active optical medium for extreme focusing and laser field amplification- describe QED effects in a collective regime

Basic Equations for Collisionless Modeling

Continuity equation in 6D phase space (r,p) for each species a

coupled via momenta of fa to Maxwell's equations

(“natural” units are used!)

Dully approaching this system is often unfeasible analytically and computationally: one needs- models- numerical simulations

Plasmas and Numerical Simulations

Plasma physics offers key and challenging projects for supercomputing with parallel machines(e.g. 2 over 10 starting projects for the Petaflop ROADRUNNER)

“Plasma physics is just waiting for bigger computers”

Back to the roots: plasma discharges

In principle there was the discharge tube …(Faraday, Langmuir, …)

“There are more things between cathode and anode than are dreamt in your philosophy” (H. Raether)

From: J.Reece Roth, “Industrial Plasma Engineering” (IOP, 2004)

“The positive column ... is what I. Langmuir had in mind when he defined plasma”

Nonlinear physics in discharges

Sheath formation near electrodes and ion acceleration:connection with laser-plasma ion accelerators

Stochastic acceleration of electrons in an AC-driven sheath:connection with electron heating in intense laser-solid interaction

Two plasma discharge applications...

Nature: lightning , chemicalreactions in the atmosphere

Industry: microprocessors production by plasma etching

... and many more

Low-temperature discharge plasmas are the basis for many technological and industrial applications: - light sources- electronics (plasma displays)- space propulsion- semiconductor etching for microcircuit production- nanofabrication- surface chemistry: industrial processing of textile or plastic materials - medical applications, sterilization- waste treatment and fuel recovery by plasma cracking- …

Apart from funding opportunities these applications may offer interesting problems

Images selected by T.Andreussi,Dipartimento Ingegneria Aerospaziale,

Università di Pisa