Monoenergetic Proton Beams from Laser Driven Shocks Dan - - PowerPoint PPT Presentation

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Monoenergetic Proton Beams from Laser Driven Shocks Dan Haberberger Neptune Laboratory, Department of Electrical Engineering, UCLA In collaboration with: Sergei Tochitsky, Chao Gong, Warren Mori, Chan Joshi Neptune Laboratory, Department of

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SLIDE 1

Monoenergetic Proton Beams from Laser Driven Shocks

Dan Haberberger

Neptune 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 Silva, Ricardo Fonseca

Instituto Superior Technico, Lisbon, Portugal

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SLIDE 2

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
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SLIDE 3

Laser Driven Ion Beam Applications

Probing 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)] AAC (Jun 2012) Neptune Laboratory

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SLIDE 4

Energy Deposition : Ions vs. Photons

AAC (Jun 2012) Neptune Laboratory

Bragg Peak for ions results in localized energy deposition

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SLIDE 5

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/

AAC (Jun 2012) Neptune Laboratory

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SLIDE 6

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=1

AAC (Jun 2012) Neptune Laboratory

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SLIDE 7

Solution : Laser Based Accelerators

Goal Cost : 10-20 million USD Table top laser system (developing) Transportation : Mirrors Only 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

AAC (Jun 2012) Neptune Laboratory

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SLIDE 8

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) AAC (Jun 2012) Neptune Laboratory

Dose Energy Energy Spread

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SLIDE 9

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)

  • f the medium

In a plasma, a shock wave is characterized by a propagating electric field at speeds useful for ion acceleration (Vsh > 0.01c) AAC (Jun 2012) Neptune Laboratory

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SLIDE 10

1D OSIRIS Simulations

Plasma 1 ne1 Te Cold Ions Plasma 2 ne2 Te Cold Ions

In Plasmas, the driver is a potential or electric field

Plasma 1 ne1 = ne2 Te1 Cold Ions Plasma 2 ne1 = ne2 Te1 Cold Ions

Expansion Shocks Driven Shocks

Ambipolar electric field of Plasma 1 is driven into Plasma 2 Initial drift causes overlap;

  • verlap causes local density

increase and again ambipolar electric field is driven into the plasma

←Vd /2 Vd /2→

AAC (Jun 2012) Neptune Laboratory

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SLIDE 11

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 Condition eɸ > 1/2mv2 AAC (Jun 2012) Neptune Laboratory

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SLIDE 12

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-intensity laser pulse

E

Shock acceleration Sheath Field (TNSA) Beam quality destroyed by TNSA fields

  • F. Fiuza | Prague, April 20 | SPIE 2011

Denavit PRL 1992, Silva PRL 2004

AAC (Jun 2012) Neptune Laboratory

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SLIDE 13
  • 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)

CO2 Laser Interacting with a Gas Jet Target

Gas plume

hybrid PIC

Extended Plasma Steepened Plasma E TNSA ~ 1/L

AAC (Jun 2012) Neptune Laboratory

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SLIDE 14

CO2 Laser Pulse Temporal Structure

Pressure = 8atm Line Separation = 55GHz Line Center : 10.6µm

400 450 500 550 600 1 2 3 4 Peak Power (TW) Time (ps)

~70ps

  • D. Haberberger et al., Opt. Exp. 18, 17865 (2010)

AAC (Jun 2012) Neptune Laboratory Experimentally Measured Temporal Profile Calculated CO2 Gain Spectrum E = 50 J Ppeak = 4TW Pulse Separation = 1/55GHz = 18.5ps 7-10 pulses long

18.5ps

~70ps

3ps

27 27.5 28 28.5 0.2 0.4 0.6 0.8 1 Normalized Amplitude Frequency (THz)

CO2 Gain Spectrum at 8atm 3ps Input Pulse Spectrum Overlapped Spectrums

1.2THz 55GHz

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SLIDE 15

0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 0.2 0.4 0.6 0.8 1 Distance (mm) dE/dx (Normalized Units) Energy Deposition of Protons in CR-39 vs. Distance

1mm CR-39

CR-39 Proton Detection

CR-39 1mm Detection: 11-15 MeV CR-39 1mm Detection: 16-19 MeV CR-39 1mm Detection: 20-22 MeV CR-39 1mm Detection: 23-25 MeV

150mm

100x100mm Imaging Proton Spectrometer Protons 10μm Laser Pulse

CR-39 1mm Detection: <1-10 MeV 1 MeV 27 MeV

AAC (Jun 2012) Neptune Laboratory

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SLIDE 16

CO2 Laser Produced Proton Spectra

1mm CR-39

Energy spreads measured to be FWHM ΔE/E ̴ 1%

Feb 22th

CR-39 #179

Jan 25th

CR-39 #92

Jan 25th

CR-39 #99

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

Noise Floor

AAC (Jun 2012) Neptune Laboratory

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SLIDE 17

Emittance Estimation

Source Size : d = 120µm Beam 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-39 150mm Laser Protons

50mm 50mm σy σx 11/30/10 22MeV

AAC (Jun 2012) Neptune Laboratory

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SLIDE 18

Plasma Density Profile

  • 600
  • 400
  • 200

200 400 1 2 3 4

X-Distance (m) Plasma Density (1019cm-3) Y-Distance (m)

  • 600
  • 300

300 600

Laser Laser Observations

1. Strong profile modification on the front side of the plasma : hole boring 2. Sharp rise (10λ) to

  • vercritical plasma

where laser pulse is stopped 3. Long (1/e 30λ) exponential plasma tail

AAC (Jun 2012) Neptune Laboratory

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SLIDE 19

2D OSIRIS Simulations : Input Deck

linear ramp exponential ramp (plasma expansion)

18 ps

Initial Plasma Profile Laser ao = 2.5 Δτ = 3ps Laser ao = 2.5 Δτ = 3ps

AAC (Jun 2012) Neptune Laboratory

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SLIDE 20

2D OSIRIS Simulations : Results

Time = 17ps Time = 52ps Time = 122ps

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SLIDE 21

2D Simulations : Energy Scaling

UCLA

AAC (Jun 2012)

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

𝐹𝑞 ∝ 𝑏𝑝

3 2

  • F. Fiuza, Phys. Rev. Lett., Submitted
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SLIDE 22

Proposed Shock Wave Acceleration at 1µm

Gas plume

hybrid PIC

Extended Plasma E TNSA ~ 1/L

AAC (Jun 2012) Neptune Laboratory 10µm Laser – Gas Jet Target 1µm Laser – Exploded Foil Target

High Power Drive Pulse Low Power Pre-heater Foil target of thickness Δx Ion beam Δx and Δt

  • Peak density for Drive Pulse is 5-

15ncr = 5-15 x 1021 cm-3

  • Extended plasma profile (1/e - 30λ)
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SLIDE 23

Conclusions

Laser-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

AAC (Jun 2012) Neptune Laboratory

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