Monoenergetic proton radiography of laser-plasma interactions and capsule implosions

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Monoenergetic proton radiography of laser-plasma
interactions and capsule implosions
Protons per unit area on detector
Imploding cone-in-shell capsule
2.7 mm
15-MeV proton backlighter (imploded D3He-filled
capsule)
Imaging detector
FSC annual meeting Chicago, Feb 28, 2007
C. K. Li R. D. Petrasso MIT
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Collaborators
R. Betti J. P. Knauer D. D. Meyerhofer W.
Theobald LLE
J. A. Frenje C. K. Li R. D. Petrasso J. R.
Rygg F. H. Séguin MIT
PI of Feb. 14 experiments
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Summary Compelling radiographic data were
obtained in 14 Feb. 2007 FSC experiments

• Monoenergetic proton radiography
• February 14 experiments with
• laser-plasma interactions and capsule
  implosions
• Excellent data obtained
• Processing analysis are underway
• Future work

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A monoenergetic backlighter in the form of a
capsule implosion has unique features
Subject implosion or laser-foil interaction
Backlighter Implosion
Monoenergetic proton spectrum
B
Laser
Ep
CR-39 Detector

• Monoenergetic quantitative results
• ? from trajectory displacements (due to
  fields)
• ? from energy loss (due to slowing in
  matter)
• Isotropic wide field of view
• multiple
  experiments simultaneously at different angles
• Different particles can be used for different
  experiments

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CR-39 detectors can be configured to match
particle
CR-39 (1000-µm-thick)
Backlighter capsule
Object imaged
Filters
For the Feb 14 experiments, only a fraction of
the back pieces of CR-39 have been processed
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Monoenergetic protons can be divided into
beamlets for deflectometry of magnetic fields
mesh
protons

Simulation of magnetic bubble
Image data
Li et al. , PRL 2006
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Different charged, monoenergetic particles can be
matched to the fields and ?R of an HED experiment
OMEGA shot 14972
?R 5 to 300 mg/cm2 rgyro
differ by X 5
Séguin et al., RSI 2003
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FSC radiography experiments February 14, 2007

• Experiments 1-3 B fields
• Laser-plasma interactions
• Effects of Au boundary
• Experiments 4-6 Fields and ?L in capsule
  implosions
• Cone-in-shell capsules
• Spherical capsules

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Experiments 1-3 B fields laser-plasma
interactions effects of Au boundary
(1) 6-beam ring
(2) 6-beam ring with Au tube
(3) beams on front and back
Preliminary data shown here
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Experiments 4-6 Fields and ?L in capsule
implosions cone-in-shell capsules spherical
capsules
(4) Cone-in-shell capsule
(5) Spherical capsule, symmetric drive
(6) Spherical capsule, asymmetric drive
Preliminary data shown here
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Multiple experiments were performed
simultaneously, taking advantage of the
isotropic backlighter
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Experiments 1 2 B fields generated by a ring
of beams on a CH foil, with and without an Au
tube
Au
Protons
CH
Side view
Top view
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Experiments 1 2 Preliminary data
Time
0 ns
0.5 ns
1.5 ns
With Au tube
Without Au tube
5 mm
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Experiment 4 First observation of rippled field
structure outside an imploding capsule!
Protons per unit area on detector
Imploding cone-in-shell capsule
2.7 mm
15-MeV proton backlighter
Imaging detector
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Experiment 4 Preliminary data
Proton energy image (darker means lower energy,
higher ? ? dl )
Visible light photograph
Proton fluence image (darker means more protons)
Before implosion
Time
During implosion (1.5 ns)
2.7 mm
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Work required to finish study of February 14,
2007 data

• Process remaining detector data
• Analyze B fields and ?L in implosions
• Cone-in-shell capsules
• Spherical capsules with symmetric drive
• Spherical capsules with asymmetric drive
• Analyze B fields due to 6 laser beams on CH foil
• Without Au tube
• With Au tube
• Analyze B fields in front- back-side
  laser-plasma interactions
• Submit scientific papers and report on these
  efforts.

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Where were going

• Develop new radiography analysis methods
• Develop improved radiography detector methods
• Pursue experiments in fuel assembly
• ?R, ?R asymmetries, fields, fusion burn images
• Request 2 shot days in next year

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New detector configurations with stacks of thin
CR-39 will be developed
500-µm-thick CR-39 Signals on all surfaces
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Mass assembly for Fast Ignition will be
studied by combining proton spectrometry and
radiography
C. Stoeckl, et al., Plasma Phys. and Control.
Fusion (2005)
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Summary Compelling radiographic data were
obtained in 14 Feb. 2007 FSC experiments

• Monoenergetic proton radiography
• February 14 experiments with
• laser-plasma interactions and capsule
  implosions
• Excellent data obtained
• Processing analysis are underway
• Future work