slide1 n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Update on LLNL FI activities on the Titan Laser PowerPoint Presentation
Download Presentation
Update on LLNL FI activities on the Titan Laser

Loading in 2 Seconds...

play fullscreen
1 / 15

Update on LLNL FI activities on the Titan Laser - PowerPoint PPT Presentation


  • 72 Views
  • Uploaded on

Update on LLNL FI activities on the Titan Laser. Fusion Science Center Meeting Chicago. A.J.Mackinnon. Feb 28, 2007. Titan laser provides a capability for combined high energy SP and LP beam experiments. Existing Janus Target Area (2x 1kJ LP beams). Titan Target Area.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

Update on LLNL FI activities on the Titan Laser


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
slide1

Update on LLNL FI activities on the Titan Laser

Fusion Science Center Meeting

Chicago

A.J.Mackinnon

Feb 28, 2007

slide2

Titan laser provides a capability for combined high energy SP and LP beam experiments

Existing Janus Target Area (2x 1kJ LP beams)

Titan

Target Area

Short-pulse: 300J in 400fs

Long-pulse: 1kJ in 3ns

Laser Bay

Switchyard upgrade will allow simultaneous Titan and Janus 2 beam

slide3

Outline

  • Titan operating reliably - @5-7 shots per day
  • Max irradiance = 3x1020 Wcm-2 at 200J, 500fs.
  • Prepulse levels low and appear reproducible - working to verify shot to shot diagnostic capability
  • Pointing accuracy appears to be very good (5-10m)
  • Proton beams with slope Tp ~ 4MeV, Emax ~ 40MeV routinely produced with 10m gold targets
  • Fast Ignition relevant experiments to take place in April will study:
    • laser to hot e coupling
    • proton conversion from hydride targets
    • Proton focusing
    • Aim for 80 shots in 5 week run
slide4

Titan long-pulse arm has been operational since Aug 06, enabling 2-beam combined SP-LP experiments

Short pulse F/3 focusing optic

Long pulse periscope

slide6

20µm diameter wire target

500µm

Laser and target alignment accuracy and laser pointing stability is 5-10µm

Titan short pulse has very good pointing and target alignment accuracy

150µm square foil target

150µm

slide7

Best focus 4.9µm FWHM containing 14% of total energy  3x1020W/cm2

15µm diameter spot encircles 50% of total energy  1x1020W/cm2

Low power images of focal region gives a peak intensity of 1x1020W/cm2 in 200J, 500fs pulse

300µm

-400µm

-200µm

0µm

+200µm

+400µm

Best focus

14%

50%

80µm

slide8

On-line fast diode and 2 optical probing are used to monitor the laser contrast and preformed plasma

Density map

Fast diode pre-pulse measurement

Interferogram at -25ps

1.38ns

0.18ns

3.18ns

500µm

Diode and preformed plasma measurements can be obtained

to examine shot to shot variations

slide9

Titan data proton beams from gold targets give 2% conversion from laser to protons above 3MeV

Titan lp vs target thickness

Titan Emax vs target thickness

Titan data

Titan data

Peak Proton Energy, Ep (MeV)

Best fit to data

Laser to Proton conversion %

1/L scaling

Target thickness (m)

Target thickness (m)

  • Conversion efficiency, peak proton energy, proton slope all reduce with increasing target thickness and pulse length
  • Data being used to benchmark PIC and LSP simulations
  • Good proton beam obtained at 10ps - encouraging for proton FI
slide10

LSP simulations show very similar behavior to experiments with plausible laser to electron coupling

Gold substrate

50J, 1MeV electrons

1000 A CHO layer

  • LSP shows slightly higher than 1/L scaling - very similar trend to data
  • Conversion from hot electrons to protons peaks at 8% for 10m Gold
  • Implies ~ 30% coupling from laser to 1MeV electron source
  • Future work will couple PIC code results as input to LSP
slide11

1D simulations predict that High Z hydrides could result in higher conversion efficiency

Fraction of energy in H+

Hot electron to proton conversion eff (%)

Fraction of energy in heavy ion

Current experiments with contaminant layers

  • Heavy ions are left behind at back surface during ion separation
erbium hydride will be tested on titan in april 07

ErH2 and ErH3

  • Films 100nm thick have been manufactured by reactive sputtering*
  • Oxide and hydrogen barriers may be necessary to maximize hydrogen content

10-15 umgold layer

* Sandia National lab

Laser

~1 um Eror U layer

  • Surface contaminants and barrier layers will be removed by ion sputtering**

10-30 nm Pd oxidationprotective layer

** M. Allen, P. K. Patel, et al., PRL 93 265004 (2004)

Erbium Hydride will be tested on Titan in April 07
slide13

Main focus of April 07 experiment will be to characterize laser MeV electron coupling

Spring expt: Laser to hot E coupling

1. Compare coupling for slabs vs cones

2. Prepulse effect inside cones

Long pulse preform beam

3. Pointing and effect of defocus (start)

slide14

The long pulse beam will be used to generate FI scale prepulse inside cones

  • = 1,

E = 1 to 100J,

  • = 3ns,

Spot ~ 30m

slide15

Summary

  • Titan operating reliably - @5-7 shots per day (depending on experiment)
  • Max irradiance = 3x1020 Wcm-2 at 200J, 500fs.
  • Prepulse levels low and appear reproducible - working to verify shot to shot diagnostic capability
  • Pointing accuracy appears to be very good (5-10m)
  • Proton beams with slope Tp ~ 4MeV, Emax ~ 40MeV routinely produced with 10m gold targets
  • Fast Ignition relevant experiments to take place in April will study:
    • laser to hot e coupling
    • proton conversion from hydride targets
    • Proton focusing
    • Aim for 80 shots in 5 week run