WG-6 Laser-Plasma Acceleration of Ions

Leader: Sergei Tochitsky, UCLACo-leader: Manuel Hegeleich, LANL

AAC-2012, Austin

Goals:Energy Frontier≥200 MeV protons≥1 GeV MeV ions

Ion Beam witha narrow energy

spread

High-RateReproducible

Ion source

Main Laser Plasma Acceleration Mechanisms

TNSA(surface)

BOA(bulk/volume)

RPA(bulk/volume)

Challenges &

Boundary conditions

Ion beamCharacteristics

ResultsExperimental & PIC

'1' nn

LA-UR-12-22090

SWA(bulk/volume)

LASERe-

ionsShock reflectedIons

Operated by Los Alamos National Security, LLC for NNSA

U N C L A S S I F I E DAccelerator and Electrodynamics

Capability Review 2010

Ion acceleration mechanisms in solid targets

TNSA(surface)

BOA(bulk/volume)

RPA(bulk/volume)

IL>1018 W/cm2

Highest q/m (H+)

Emax~60 MeV

CE ~ 1-10%

Typically exp. decaying

IL>5x1019 W/cm~100 nm

Ultra-high contrast (>108)

Difficulty

IL>1020-1022 W/cm2

1-50 nmUltra-high contrast (>108)

1D geometry

Requirements

Ion beamCharacteristics

All species

Emax>100 MeV/amu,

CE ~ 10%

Typically exp. decaying

All species

Emax* >1 GeV/amu,

CE* 10%

Monoenergetic distribution**Prediction

Accelerationmechanism

LA-UR-12-22090

1-100 micron Targets

1

11*

* *

0

e

e

JEln8.08.4*

Estimated Emax =54MeV

Proton

OAPF=2.14

Laser pulse8 J , 40fs, contrast level 1x1010

FWHM 4x3 mm2

1.6x1021 Wcm-2

40 MeV proton generation by 7.5 J 200TW laser pulse interaction with robust SUS 2 mm target

kTe confirms 2x1021 Wcm-2 laser intensity on target

FWHM~40fs

Electron spectrum

kTe ~ 16MeV

〜 9.3 MeV

60°

＋ 5.2°38.9〜 40.5 MeV

5°+10.3°

37.2〜 38.9 MeV

20°

＋ 11.3°

25.5〜 27.5 MeV

30°

+10.3°

Strong charge separation regime

Ogura, Nishiuchi, Pirozhkov et al. 2012 Opt. Let.

6

From TNSA towards the RPA regimeJETI40 with plasma mirror: • 15 nm Parylene (C8H6F2) reveals proton peaks between 1…2.1 MeV on top of exponential background

• supported by numerical 2D PIC simulations

Target thickness [µm]

Prot

on c

utoff

ene

rgy

[MeV

]

Al(Z=13)

Ti(Z=22

)

Cu(Z=29)

Ag(Z=47)

Ta(Z=73)

POLARIS laser: • TNSA study on target material and thickness• complex interplay between target and laser parameters turned out

Simulations show a competition between two parameters.

M. Carrié et al. Phys. Of Plasma, 16, 053105 (2009).

2D simulations using the PIC code CALDER.

Ex α λd0/lss*(nhot*Thot)1/2

T. Grismayer et P. Mora. Phys. Plasmas 13, 032103 (2006).

Plasma gradient: Increases with time because of target expansion.

Laser-plasma coupling: Absorption and electron-temperature.

Seite 8 Mitglied der Helmholtz-GemeinschaftKarl Zeil k.ziel@hzdr.de www.hzdr.de HZDR

Zeil et al. Nature Communications 6:874 (2012)

Efficient proton acceleration during intra-pulse phase

Test experiment with tilted pulse front• Prominent non-target-normal proton beam emission• Spatiotemporal asymmetry restricted to coherent

short pulse• Proton deflection as signature of the promptly

accelerated electrons• Efficient proton acceleration during intra-pulse

phase prior to the plasma expansion (pre-thermal)

Proton beam deflection at oblique incidence• Most energetic protons are deflected in experiment• History of most energetic protons from 2D PIC

simulation overlaid1. Protons initially emitted under optimal angle2. Injection into expanding sheath

LA-UR-12-01121

High Energy, High Quality TNSA Beams From Microcones and Limited Mass Targets

1E+16 1E+190.1

1

10

100

30 - 100 fs101 - 299 fs300 - 400 fs401 - 1050 fs540 - 685 fs Trident (Constant Spot)Power (540 - 685 fs Trident (Constant Spot))640 - 1200 fs Trident (Constant Energy)10000 fs Omega EP (Constant Spot)

Laser Intensity (W/cm2)

Max

imum

Pro

ton

Ener

gy (M

eV)

60

Preplasma from high contrast (>10-10 ASE) Trident

M. Schollmeier et al. in prep (2012)

Delay (ps)

Cont

rast

Leve

lLaser contrast

108

t = -7ps

-5

K. A. Flippo et al. J. Phys.: Conf. Series 244 022033 (2010)

S. Gaillard et al., Physics of Plasmas 18, 056710 (2011)

“main sequence” follows I1/2

Cons

tant

spo

t size

Constant e

nergy

Cu Ka 2D transverse

image

67 MeV from Cones

High Quality Beams

Trident 75 MeV from LMT

Blue and green correspond to lineouts above

24MeV Proton Bunches Using Microstructured Snow Targets Irradiated by 5TW LaserHebrew University/MBI/NRL

1 13 20 241E+02

1E+03

1E+04

1E+05

1E+06

Protons energy bins

proton energy [MeV]

coun

ts [p

roto

ns/m

m2]

Laser CR-39Stack

Snow target

Protons

ThompsonParabola

Snow Landscape

• Microstructured Snow Targets are providing:High laser-target coupling (95%); Easy to manufacture and control; Debris free ; Reduce demands on pre-pulse high contrast ratio; Geometrical features that enhance acceleration

• 24 MeV protons were measured during the interaction of a 5TW laser with micro-structured snow target

Front curvature - Heating Mechanism

Electron Density

Thin

Electron Density Electron Density

Thick

•Finite Spot effects strongly influence heating•Target deformation increases with decreasing target thickness

ssteinke@lbl.gov 12

Formvar (mass: C:H~ 5:1)

~25nm (35fs), ~13nm (70fs)Targ

et

• intensity dependant optimum

• low divergence (140mrad)

• containing ~6.5% of the laser energy (0.5% H+)

• RT signatures appearing at highest intensity & thinnest target

Res

ults

IIStable RPA with two-component target a0~5

• l = 25 nm target

• circular laser polarization

• average of 4 consecutive shots

• creation of a stable ion-ion interface at 2MeV/amu

Res

ults

I

V. Hudik, UT

Vsh

ne

ncr

laser

2Vsh

V 2V

0

foil

jet •5% energy spread •5x106 protons within 5-mrad•spectral brightness 7×1011 protons/MeV/sr

Igor Pogorelsky, BNL“Optical probing of laser hole-boring into overdense plasma”

Operated by Los Alamos National Security, LLC for NNSA

U N C L A S S I F I E DAccelerator and Electrodynamics

Capability Review 2010

20 40 60 80 100 120

104

105

106

Inte

nsity

(PS

L/M

eV/m

sr)

Energy (MeV)

H+ 10.5°-11.5°

Exceeding 100MeV/amu with BOA with a 150 TW laser

>100MeV H+ from CH2 target (measured on IP and CR39-Stack)

Increased proton energies to over 100MeV

Increased maximum energy by a factor of 2 over previous results achieved with TNSA/BOA

200 400 600 800 1000

103

104

105

106

Inte

nsity

(#/M

eV/m

sr)

Energy (MeV)

C6+ 0.5°-1.5°

>1GeV C6+ from Diamond target (measured on CR39 and Stack)

Increased carbon C6+ energies to over 1GeV

Increased maximum energy by a factor of 20 over previous results achieved with TNSA

CR39 Stack

LA-UR-12-22090

15

Up to 8 Gray in a single 1 ns proton bunch, 1.3 m from target

1 cm

Combination of all “cutting edge” methods for an application• PM + nm targets (high particle numbers, low secondary radiation)• Compact setup with PM-QPs (setup could be smaller than 50 cm)• low laser energy (400 mJ, in principle 10 Hz operatable)• truly ns-biology (single shot high dose)• E = 5.5 MeV, DE/E=6% cells

Courtesy of Dan Keifer

G. Turchetti et al University of Bologna Transport and post acceleration

The LILIA experiment at LASERLAB Frascati (Rome) is devoted to proveInjection at 30 MeV of a TNSA proton beam into a compact linac ACLIP

Phase 1: I=1020 a=8 diagnostics and targets tests (2012) Phase 2: I=2 1021 a=30 injection and post acceleration

3D PIC simulations with PIC codes AlaDyn and Jasmine (GPU) with composite

targets (foil+foam layer) give more than 108 protons at E=30 MeV DE=0.5 MeV

Energy selection with solenoid and collimators allows to post-acc ~ 107 protons

First moduleof ACLIP

Shock Wave Acceleration in gas jetUCLA

Gas plume

hybrid PICExtended Plasma

E TNSA ~ 1/L

10µm Laser – Gas Jet

F. FiuzaSWA scaling (submitted PRL)

Emax ~a0 3/2

Advanced Accelerator Concepts Workshop, June 11-15, 2012, Austin, Texas

18

Strong shockwave generationM. Helle, D. Gordon, D. Kaganovich and A. Ting

• A block placed within the gas jet aids in coupling laser energy into shock.• A sharp gradients produced by this shock has been seen in experiments and

simulations preformed using the hydrodynamics code SPARC.• Experiments show density gradients <50 um and peak density >1020 cm-3

*D. Kaganovich, M.H. Helle, D.F. Gordon, and A. Ting, Phys. Plasmas 18, 120701 (2011)

10 TW Laser

Shockwave Laser

Gas Flow

Shock Front

Gas Jet w/Block

100 μm

50 μm

Laser ion acceleration with low density targets

E. d’Humières, S. Bochkarev and V.T. TikhonchukUniv. Bordeaux - Lebedev Institute (Russia)Efficient underdense laser proton

acceleration is possible for various laser and target conditions. Depends strongly on the laser pulse shape. First experimental validation at LULI (few MeV protons with 500 nm exploded foils and few J of laser energy). First high laser energy experiments at Titan/LLNL this summer

The shock regime can be very efficient and offers an interesting alternative to overdense ion acceleration schemes. Modeled using 2D and 3D PIC simulations and a Boltzmann-Vlasov-Poisson Difficult to use gas jets with nowadays nozzle technology but exploded foils could help to highlight this mechanism experimentally.Accelerated proton beam characteristics are similar to the ones obtained using solid targets. The ratio of maximum proton energy over laser energy is even higher for low density targets (when interaction is optimized in both cases). High laser energy and intensity allow to explore high density/thickness couples and lead to very energetic ions.

• Requires high laser energies and long gradients to efficiently reflect ions with the targets available today.

UCLA

Laser-Driven Ion Beams:applications

Laser-Plasma Potential Applications

• >50 MeV high-brightness injector for a large RF accelerator.

• ~200 MeV/u Plasma accelerator for hadron therapy.• 5-10 MeV ion source at 1-10 Hz (for example for F18

Medical isotopes for PET).• Neutron source driven by LDIA, very short neutron

pulses for material science.• Very high peak current ion beams for R & D. :WDM,

Fast Ignition, etc.

Pulsed Neutron Source

p• d

d

0224_2012_shot#4

10 mm Cu with D20 ice coating

1 2 3 4 5 6 7 8 9 1010

9

1010

1011

1012

1013

X: 8.495Y: 4.59e+009

Ion energy (MeV)

signa

l / M

eV /

ster

adia

n (a

.u.)

Ion spectra for shot - Not yet calibrated

A. Maksimchuk, UM

X-Ray & Neutron Generation

Experiment at Trident20-40 MeV Deuterons

1010-1011 Neutrons/shotM. Roth, DTU

Status: Where we are in 2012

UCLA, Neptune Lab

LANL

JAEA>100 MeV from a nanofoil,LANL22 MeV protons with a narrow Energy spread from H2 gas jet plasma UCLA40 MeV protons from a TNSAJapan

-K. Zeil et. al., New J. Phys 12, 045015 (2010)

AAC-2012, Austin