lecture 1. introduction - pte-ttk fizikai intézet · introduction ¾conventional accelerator...

Preparation of the concerned sectors for educational and R&D activities„Preparation of the concerned sectors for educational and R&D activities related to the Hungarian ELI project ”

Ion acceleration in plasmasIon acceleration in plasmas

Lecture 1. Introduction

Dr Ashutosh SharmaDr. Ashutosh SharmaZoltán Tibai

1TÁMOP-4.1.1.C-12/1/KONV-2012-0005 projekt

Contents

1 Introduction1. Introduction

2. Application of laser driven energetic ions2. Application of laser driven energetic ions

3. Short description on laser-driven ion acceleration mechanismp

4. Applicability in context of next generation laser facilities

TÁMOP-4.1.1.C-12/1/KONV-2012-0005 projekt 2

Introduction

When any material is heated to a sufficient degree, itsy g

constituent atoms separate into negative electrons and positive

i Thi t t f tt i ll d lions. This state of matter is called plasma.

Plasma has unique properties that make it an attractive

medium for particle acceleration.

Ion/Proton acceleration from plasma (from solid/gastargets) using high power lasers is an exciting field with a variety

f li ti i i di i d i d tof applications in science, medicine, and industry.


IntroductionConventional accelerator cavities can only sustain acceleratingelectric field gradients of the order of 106 V/m, as they areli i d b h l i b kd f h l i llimited by the electric breakdown of the accelerator materials.

Plasmas are already broken down and so the accelerating fieldsPlasmas are already broken down and so the accelerating fieldsare not limited by this effect.

Plasmas exhibit quasineutrality, i.e. the negative charge densityof the electrons is equal to the positive charge density of theiions.

Any significant separation of positive and negative charge isAny significant separation of positive and negative charge isaccompanied by strong electrostatic restoring fields. Thesetransient fields are of interest as compact ultrahigh-gradient


p g gaccelerating structures.

Introduction

Accelerating Field due to Laser driven strong chargetiseparation

+++

--

-- --EL +

++ -

-- -

- -L

E+++ -

-++ ++

+

+ +

Eacc

+ - +High quasi-stationary electric (and magnetic) fields are producedEL ≈ Eacc ≈ tens GV/cm ⇒ efficient charged particle acceleration


L acc g p

Introduction

Cutting edge laser technology is capable of producing

pulses of light focusable to intensities of 1021-1022 W/cm2. At these

intensities the electric field of the laser rips electrons from theirintensities the electric field of the laser rips electrons from their

atomic orbitals and accelerates them to highly relativistic energies,

Ekinetic >> mec2.

These extremely energetic electrons propagate through theThese extremely energetic electrons propagate through the

surrounding material, causing further plasma formation. Recent

studies have indicated that ions can be efficiently accelerated

during such interactions via several mechanisms.


g

IntroductionLaser Driven Ion Acceleration in thin Solid film TargetsIf an ultraintense and ultrashort laser pulse hits the surface of a thin solidpfilm, intense and energetic (Multi- MeV!) ion “beams” are effectivelyproduced -

Target F t i

E. L. Clark et al. Phys. Rev. Lett. 84, 670 (2000)

Target Fast ions

A. Maksimchuk, et al., ibid. 84, 4108 (2000) R. Snavely et al. ibid. 85, 2945 (2000)

Typical physical parameters of the accelerating system:

Laser Electron cloud

yp p y p g y

Laser – energy: 0.1-1000 J, pulse duration: 10-1000 fs, intensity: 1018-1021 W/cm2

solid target – type: conductors, insulators, thickness: 0.01-100 μml t d i t i l diti th i i diti


accelerated ions – protons in usual conditions, other ions in proper conditions

Proposed applications of ion beamRadiography (density measurement)

Deflectometry (field measurement)Large numbers

Deflectometry (field measurement)

Isochoric heating of matter@ moderate energyDivergence controlShort burst (narrow band)

Fusion Energy (Fast Ignition)

Injection into conventional accelerators

( )


Cancer therapy

Production of isotopes for PET

Industrial applicationsW d

pp

(implantation, lithography)Warn dense matter, solid density1-100 eV


Nuclear/particle physics applications

Proposed applications and requirementsRadiography (density measurement)

Deflectometry (field measurement) High-energy (50-250 MeV p+)Deflectometry (field measurement)

Isochoric heating of matter

High-energy (50-250 MeV p )Narrow band (ΔE/E ~ %)Divergence control/transport



+ High repetition, stability, beam monitoring…(!!!)Injection into conventional accelerators

Cancer therapy

g ( )


Industrial applicationspp

(implantation, lithography)


Nuclear/particle physics applications

Proposed applications and requirementsRadiography (density measurement)

Deflectometry (field measurement)Deflectometry (field measurement)

Isochoric heating of matter



Very high energy > GeV(or >> GeV)High repetitionInjection into conventional accelerators

Cancer therapy

High repetition


Industrial applicationspp

(implantation, lithography)+ High repetition, stability, beam monitoring…(!!!)


Nuclear/particle physics applicationsg ( )

Bragg Peak for ions results in localized energy depositionenergy deposition

TÁMOP-4.1.1.C-12/1/KONV-2012-0005 projekt 11http://en.wikipedia.org/wiki/Bragg_peak

Laser driven Ion Acceleration Mechanism

solid targetpre-plasma Light ion

IF THE e- POPULATION IS DOMINATED BY ATHERMAL SPECTRUM

l ti l t i fi ld d t t h targetp p(underdense)

glayeraccelerating electric field due to strong charge

separation between hot electrons expanding invacuum and the bulk target

Laser

Relativistice- current

Target Normal Sheath Acceleration (TNSA)Wilks et al., Phys. Plasmas 8, 542 (2001)

1 3

Laserpulse

2

return current

IF THE ROLE OF THE THERMAL e-

POPULATION IS “SUPPRESSED”accelerating electromagnetic field due to 2

front rearmain

accelerating electromagnetic field due tocharge separation induced by the balancebetween radiation pressure and electrostaticforce front

surfacerearsurface

pulse

pre-pulse

force

Radiation Pressure Acceleration (RPA)Esirkepov et al., Phys. Rev. Lett. 92, 175003 (2004)


p , y , ( )Macchi et al., Phys. Rev. Lett. 94, 165003 (2005)

Target Normal Sheath Acceleration (TNSA)


TNSA

Typical results: Target: 10 µm AlTemperature~ 1.8 MeV for 12 J~ 5 MeV for 85 J

Energy conversionη ~ 2·10-3 for 12 J

2η ~ 5·10-2 for 85 Jη ~ 2·10-1 for 400 J

Efficieny at 30 50 MeVEfficieny at 30-50 MeVηhot ~ 10-5-10-4

T i l diTypical divergence:30-60°


Zepf et al, PRL 84, 670, (2000), Snavely et at., PRL 85, 2945, (2000)

TNSA

Beam quality substantially better than conventional particle accelerators

nm scale surface perturbations are still visiblenm scale surface perturbations are still visibleExcellent beam quality of <0.004 mm mrad


TNSA

Laser accelerated protonsmore than just a nice technology?- more than just a nice technology?

Unique for short pulse durationi ll d f ti l d bi- unrivalled for time resolved probing

- excellent emittance

Compared to conventional acceleratorsWhat do we need to be competitive?

- Averaged fluxg- Narrow angular distribution- Narrow energy distribution (not simply slicing)- Higher endpoint energyHigher endpoint energy(200 MeV protons required for 200 mm range in H2O, e.g. for

hadron therapy)


TNSA

Energy Scaling

Early experiments and modeling suggest that extend the tail to 200 MeV.Early experiments and modeling suggest that extend the tail to 200 MeV.Should be possible with currently extending lasers.


Radiation Pressure Acceleration (RPA)


RPA

- Using circular polarisation at normal incidence

Laser and electric field in force balanceLaser and electric field in force balance.Charge separation due to laser sets up field that accelerates ions.

Momentum conservation determines ion velocityMomentum conservation determines ion velocity.


RPA vs TNSA


RPA vs TNSA

Almost all protons are in

Silva et al. PRL 9015002 (2004)Esirkepov et al.,protons are in

tiny phase space volume

PRL 175003 (20

Note: beam is quasineutral


Shock Wave Acceleration (SWA)

A disturbance travels at supersonic speeds through a medium Subsonic Sonic SuperSonicp

A i d ill b ild h f f di b h kAt supersonic speeds, pressure will build at the front of a disturbance shock wave.Characterized by a rapid change in pressure (density and/or temperature) of the medium.

In a plasma a shock wave is characterized by a propagating electric fi ld d f l f i l i ( 0 01 )


field at speeds useful for ion acceleration (vsh > 0.01c)

Shock formation in laser driven plasmas

Shockacceleration

High Intensity Laser Pulse EE

acceleration

Sh th Fi ldSheath Field(TNSA)

Linearly polarized laser incidence upon an overcritical target creates and heats the plasma

Beam quality destroyed by TNSA fieldsthe plasma

Ponderomotive force creates density spike and imparts a velocity drift on a

f l

by TNSA fields

surface plasma


Denavit PRL 1992, Silva PRL 2004

CO2 Laser Interacting with a Gas Jet TargetGas jet target has advantages for Shock Wave Acceleration (SWA)

Gas jets can be operated at or above 1019 /cm3 plasma density (ncr for 10µm)

Long scale length plasma on the b k id f th j t i hibit

Ion beamCO2 laser

back side of the gas jet inhibits strong TNSA fields preserving proton spectrum

High repetition rate source

Clean source of ions (H2, He, N2,

SteependPlasma

ExtendedPlasma

2 2O2, Ar, etc…)

Low plasma densities allows bi f l d i i


probing of plasma dynamics using visible wavelengths

Collisionless shock in laser-produced plasmaExperimental setup, the CO2 laser pulse profile and an image of a CR39 detector. Proton energy spectra

Laser-produced plasma profile.

Haberberger et al, Nature Physics 8, 95 (2012)


g , y , ( )

Simulated Proton Spectra

1D-PIC ResultsOsiris PIC Results

(Haberberger et. al., Nat. Phys. 8, 95 (2012)


Applicability in context of ELI facilityThe proposed course has focus on high power, ultraintense laser

interaction with overdense plasma (solid / gas) which has high relevance in theinteraction with overdense plasma (solid / gas) which has high relevance in the

development of laser-driven particle accelerators, X-ray sources and techniques

for controlling the shape and contrast of intense laser pulsesfor controlling the shape and contrast of intense laser pulses.

The proposed research has high relevance in medical applications and

i bi di l i i d h hi h l i h i l i fin biomedical imaging, and has high relevance in the implementation of next

generation lasers: linked to existing cutting edge projects in the field, such as

Extreme Light Infrastructure (ELI) and High Power Laser Energy Research

Facility (HiPER).

ELI: http://www.eli-laser.eu/

HiPER: www.hiper-laser.org


Problems

Q1.1. What is Plasma?A1 1 F th St t f M ttA1.1. Fourth State of Matter.

Q1.2. Why do we use plasma for particle acceleration?Q1.2. Why do we use plasma for particle acceleration?A1.2. Accelerating field in plasma is much stronger than conventional

accelerator.

Q1.3. Why proton or ion beam is better for cancer treatment?A1 3 Suitable for high energy depositionA1.3. Suitable for high energy deposition.

Q1.4. Where the isochoric heating of matter is relevant?A1.4. Astrophysics, Inertial Confinement Fusion.


Problems

Q1.5. Define the fusion energy!A1.5. It is the process where atomic nuclei collide together and release

energy (in the form of neutrons).

Q1.6. Show the fusion of deuterium and tritium?A1.6.

Q1.7. What is the role of proton beam in cancer treatment?A1.7. Proton charged particles damage the DNA of cancer cells.A1.7. Proton charged particles damage the DNA of cancer cells.


Problems

Q1.8. What is the reason proton beam is better than x-ray beam for cancer t t t?treatment?

A1.8. Due to heavier mass proton beams are less scattered.

Q1.9. How does ion accelerate in laser driven plasma?A1.9. Electric field is generated due to charge separation by laser.

Q.1.10. What is the source of proton emission in metallic target whose chemical composition does not include hydrogen?chemical composition does not include hydrogen?

A.1.10. Impurities in the form of water or hydrocarbon present on solid surface.


References

1. F. F. Chen, Introduction to Plasma Physics, (Plenum Press, New York, 1974).

2 M hi l R i f M d Ph i 85 751 (2013)2. Macchi et.al., Review of Modern Physics 85, 751 (2013).


lecture 1. introduction - pte-ttk fizikai intézet · introduction ¾conventional accelerator...

Documents