Monoenergetic Proton Beams from Laser Driven Shocks

Monoenergetic Proton Beams from Laser Driven

Shocks

Dan HaberbergerNeptune Laboratory, Department of Electrical Engineering, UCLA

In collaboration with:Sergei Tochitsky, Chao Gong, Warren Mori, Chan Joshi

Neptune Laboratory, Department of Electrical Engineering, UCLA

Frederico Fiuza, Luis SilvaInstituto Superior Technico, Lisbon, Portugal

Outline

AAC (Jun 2012)Neptune Laboratory

• Applications of Laser Driven Ion Acceleration (LDIA) : Hadron cancer therapy• Localized energy deposition : Bragg Peak• Therapy centers : conventional accelerators vs. lasers• Ion source requirements

• Collisionless Shock Wave Acceleration (SWA) of protons• 1D OSIRIS Simulations• Laser driven case

• UCLA proton acceleration experiment : CO2 laser and a H2 gas jet target• Results : Spectra, emittance• Interferometry : Plasma density profile

• 2D OSIRIS simulations• Modeling the experiment• Scaling to higher power lasers• Using 1µm laser systems

• Conclusion

Laser Driven Ion Beam ApplicationsProbing of strong electric fields in dense plasma on the picosecond timescale

– ~1μm resolution, 5-20MeV– Borghesi, Phys. Plasmas (2002)• 50μm Ta wire• Imaging with 6-7MeV protons

-15ps -5ps 5ps

VULCAN Laser, 20J, 1019W/cm2

Hadron Cancer Therapy– 250MeV, 109-1010 protons/s– ΔE/E ≤ 5%

Fast Ignition– 15-23MeV– <20ps– Eff = 10%

Picosecond injectors for conventional accelerators– 1-10MeV, <.004 mm.mrad, <10-4 eV.s [Cowan, Phys. Rev. Lett. (2004)]


Markus RothWG6 : Tuesday 1:30

Energy Deposition : Ions vs. Photons


Bragg Peak for ions results in localized energy deposition

Multi-beam Localization

Radiation dose relative to peak (100%)

Simulations of Irradiating the Human Skull

GSI Helmholtz Centre for Heavy Ion Research in Darmstadt http://www.weltderphysik.de/gebiet/leben/tumortherapie/warum-schwerionen/


http://www.weltderphysik.de/gebiet/leben/tumortherapie/warum-schwerionen/

Problem : Cost and Size

Heidelberg Ion-Beam Therapy Center, Commissioned in 2009

Cost : ~200 Million USD• Accelerator ring (20m)• Transport magnets• Complicated Gantry• Radiation shielding

Only a few in operation along with ~30 small facilites• 10’s of thousands of people

treated• Need more than an order of

magnitude more therapy centers

20 meters

http://www.klinikum.uni-heidelberg.de/Welcome.113005.0.html?&L=1AAC (Jun 2012)Neptune Laboratory

25 meters

http://www.klinikum.uni-heidelberg.de/Welcome.113005.0.html?&L=1

Solution : Laser Based Accelerators

Goal Cost : 10-20 million USDTable top laser system (developing)Transportation : MirrorsOnly has focusing magnet Gantry : small, protons generated in direction of patient

M. Murakami, et al., AIP Conf. Proc. 1024 (2008) 275, doi:10.1063/1.2958203


Proton Beam Requirements

Radiation Beam Requirements

2 Gray in 1 liter tumor in a few minutes-Translates to 1010 protons per second

Proton energies in range of 250 MeV

Energy Spread of ~5%

Focusability, Energy Accuracy, Energy Variability, Dose Accuracy, etc.

Lasers can accelerate up to 1012 protons in a single shot

Worlds most powerful lasers have produced 75 MeV protons

Vast majority of beams have continuous energy spread

Future Work

Laser Driven Ion Acceleration (LDIA)


Dose

Energy

EnergySpread

What is a Shock Wave?

Subsonic Sonic Supersonic

A disturbance that travels at supersonic speeds through a medium

• At supersonic speeds, pressure will build at the front of a disturbance forming a shock

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


1D OSIRIS Simulations

Plasma 1ne1

Te

Cold Ions

Plasma 2ne2

Te

Cold Ions

In Plasmas, the driver is a potential or electric field

Plasma 1ne1 = ne2

Te1

Cold Ions

Plasma 2ne1 = ne2

Te1

Cold Ions

Expansion Shocks Driven Shocks

Ambipolar electric field of Plasma 1 is driven into

Plasma 2

Initial drift causes overlap; overlap causes local density

increase and again ambipolar electric field is driven into the

plasma

←Vd /2Vd /2→


1D Sims : Driven Shocks (Te = 511 keV Cs = 0.0233c).

Wave train response

Proton trapping begins

Proton reflection begins

Strong damping of wave

No interaction

Reflection Conditioneɸ > 1/2mv2


Shock formation in laser driven plasmas

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

• Ponderomotive force creates density spike and imparts a velocity drift on surface plasma

High-intensitylaser pulse E

Shockacceleration

Sheath Field (TNSA)

Beam quality destroyed by TNSA fields

F. Fiuza | Prague, April 20 | SPIE 2011

Denavit PRL 1992, Silva PRL 2004


• Gas jets can be operated at or above 1019 cm-3 (ncr for 10µm)

• Long scale length plasma on the back side of the gas jet inhibits strong TNSA fields preserving proton spectrum

• High repetition rate source• Clean source of ions (H2, He, N2,

O2, Ar, etc…)• Low plasma densities allows for

probing of plasma dynamics using visible wavelengths

Gas jet target advantages for Shock Wave Acceleration (SWA)

CR-39Nuclear Track

Detectors

CO2 Laser Interacting with a Gas Jet Target

Gas plume

hybrid PICExtended PlasmaSteepened

PlasmaE TNSA ~ 1/L


120µm

1mm

IL = 5x1016 W/cm2

Interferometry1ps 532nm

CO2 Laser Pulse Temporal Structure

Pressure = 8atmLine Separation = 55GHz

Line Center : 10.6µm

400 450 500 550 6000

1

2

3

4MARS Shot # 14300

Peak Pow

er (T

W)

Time (ps)300 400 500 600

0

0.5

1

1.5

2

2.5MARS Shot # 14405

Peak Pow

er (T

W)

Time (ps)

~70ps ~110ps

D. Haberberger et al., Opt. Exp. 18, 17865 (2010)AAC (Jun 2012)Neptune Laboratory

Experimentally Measured Temporal ProfileCalculated CO2 Gain Spectrum

E = 50 JPpeak = 4TW

Pulse Separation = 1/55GHz = 18.5ps7-10 pulses long

18.5ps

~70ps3ps

27 27.5 28 28.50

0.2

0.4

0.6

0.8

1

Normalized Amplitude

Frequency (THz)

Frequency Spectrum

CO2 Gain Spectrum at 8atm

3ps Input Pulse SpectrumOverlapped Spectrums

0 50 100 150 2000

0.2

0.4

0.6

0.8

1

Time (ps)

Amplified PulseTemporal Structure

18ps = 1/55GHz

3ps

1.2THz

55GHz

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 660

0.2

0.4

0.6

0.8

1

Distance (mm)

dE/d

x (N

orm

aliz

ed U

nits

)

Energy Deposition of Protons in CR-39 vs. Distance

1mm CR-39

CR-39 Proton Detection

CR-391mm

Detection:11-15 MeV

CR-391mm

Detection:16-19 MeV

CR-391mm

Detection:20-22 MeV

CR-391mm

Detection:23-25 MeV

150mm 100x100mm Imaging ProtonSpectrometer

Protons

10μm Laser Pulse

CR-391mm

Detection:<1-10 MeV

1 MeV27 MeV


CO2 Laser Produced Proton Spectra

1mm CR-39

Energy spreads measured to

be FWHM ΔE/E 1% ̴

Feb 22th

CR-39 #179Jan 25th

CR-39 #92Jan 25th

CR-39 #99 Haberberger, Tochitsky, Fiuza, Gong, Fonseca, Silva, Mori, Joshi, Nature Phys., 8, 95-99 (2012)

Noise Floor


Emittance Estimation

Source Size : d = 120µmBeam Size (RMS) : σx 5.7mm ̴ σy 2.2mm ̴Divergence : θx 37mrad ̴ θy 14mrad ̴Emittance : εx = d.θx = 4.6mm.mrad εy = d.θy = 1.7mm.mrad

H2 Gas Jet

CR-39150mm

Laser

Protons

50mm

50mm

σy

σx11/30/1022MeV


Plasma Density Profile

-600 -400 -200 0 200 4000

1

2

3

4

X-Distance (m)

Plas

ma

Den

sity

(1019

cm-3

)Y-

Dis

tanc

e (

m)

-600

-300

0

300

600

Laser

LaserObservations1. Strong profile

modification on the front side of the plasma : hole boring

2. Sharp rise (10λ) to overcritical plasma where laser pulse is stopped

3. Long (1/e 30λ) exponential plasma tail


2D OSIRIS Simulations : Input Deck

linear ramp

exponential ramp(plasma expansion)

18 ps

Initial Plasma Profile

Laserao = 2.5Δτ = 3ps

Laserao = 2.5Δτ = 3ps


2D OSIRIS Simulations : Results Time = 17ps Time = 52ps Time = 122ps

2D Simulations : Energy Scaling

UCLA

AAC (Jun 2012)

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

𝐸𝑝∝𝑎𝑜3 /2

Proposed Shock Wave Acceleration at 1µm

Gas plume

hybrid PICExtended Plasma

E TNSA ~ 1/L


10µm Laser – Gas Jet Target 1µm Laser – Exploded Foil Target

High Power Drive Pulse

Low PowerPre-heater

Foil target of thickness Δx

Ion beam

Δt

Δx and Δt • Peak density for Drive Pulse is 5-15ncr

= 5-15 x 1021 cm-3 • Extended plasma profile (1/e - 30λ)

ConclusionsLaser-driven, electrostatic, collisionless shocks in overdense plasmas

produce monoenergetic protons at high energies• Protons accelerated to 15-22 MeV (at IL ~ 4x1016 W/cm2)• Energy spreads as low as 1% (FWHM)• Emittances as low as 2x4 mm·mrad• Interferometry uncovers unique plasma profile• Plasma simulations elucidate shock wave acceleration of

protons through the backside of the plasma


Step towards achieving 200-300 MeV protons needed for cancer therapy

• Simulations show scaling to ~300 MeV with a laser ao = 15

• Proposed method of exploding foil target for 1µm laser systems

Supporting Simulated Interferogram

Measured Plasma Profile

Simulated Plasma Profile

-600 -400 -200 0 200 4000

1

2

3

4

X-Distance (m)

Plas

ma

Den

sity

(1019

cm-3

)


1μm Nd:GlassCPA System

10μm TEA MasterOscillator

8atm Regenerative

Amplifier2.5atmLarge ApertureFinal Amplifier

3ps, 3mJ

500ns30mJ 3ps

~nJ

3ps4mJ3ps

350mJ

3ps 100J

CS2 Kerr Cell

Low Pressure CO

2 Amplifier

Neptune CO2 MOPA Laser System


1μm Glass CPA System

1μm GlassMaster

Oscillator

1μm GlassRegenerative

Amplifier

Grating

Grating

Grating

Stretcher

Compressor

500fs100mW

~1ns70mW

~1ns4mJ

3ps3mJ

5Hz

110MHz

CS2 Kerr SwitchingCS2 Kerr CellPolarizer Analyzer1µm from CPA

10µm from MO

10µm1µm3ps 500ns

30mJ1mJ3ps1nJ

10µm• I90°(1µm) = 25 GW/cm2

• Signal-to-background contrast = 105

10µm Seed Production


100Jwo = 6.5cm

I = 30-140 GW/cm2

P = 1-15 TW

• Pressure : 2.5atm• Δνpressure = 14GHz• go = 2.6%/cm

3-Pass Final Amplifier4mJ

wo = 0.5cmI = 200 MW/cm2

350mJwo = 1cm

I = 4 GW/cm2

20x35cm

L = 2.5m

Haberberger, Tochitsky, Joshi, Optics Exp., 18, 17865-17875 (2010)

50 100 150 200 250 3000

0.2

0.4

0.6

0.8

1

Pulse train afterRegenerative Amplification


Time (ps)180 200 220 240

0

0.2

0.4

0.6

0.8

1

Pulse train afterFinal Amplification


Time (ps)

goL = 19.5

18ps45J, 3ps15TW

400 450 500 550 6000

1

2

3

4MARS Shot # 14300

Peak Pow

er (TW)

Time (ps)300 400 500 600

0

0.5

1

1.5

2

2.5MARS Shot # 14405

Peak Pow

er (TW)

Time (ps)

~70ps ~110ps

100J

Final Amplification


Specs and Results 10µm Pulse Measurement

4mJ

8atm CO2 moduleΔνp = 37GHz

~nJ

50% OC

CS2 Kerr Cell

Streak Camera

10µm

Red DiodeLaser

0 20 40 60 80 100 120 140 160-0.2

0

0.2

0.4

0.6

0.8

Time (ps)

Nor

mal

ized

Am

plitu

de

18ps ~3.3ps 2 2

2

16ln 2 ln0 o

en enr

Gz

Regenerative Amplification

Cross Polarizers


LDIA Experimental Setup F=1.5 → 2wo = 120μm

H2 Gas Jet

Laser TransmissionDiagnostic

Stack of CR-39Nuclear Detector

To Streak Camera Diagnostic

Laser ReflectionDiagnostic

Protons

NaCl

CO2 Laser50J, 3ps pulse trainDiameter = 10cm

Picosecond Probe


Monoenergetic Proton Beams from Laser Driven Shocks

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