Final Optic Research – Progress and Plans
This presentation is the property of its rightful owner.
Sponsored Links
1 / 22

M. S. Tillack PowerPoint PPT Presentation


  • 56 Views
  • Uploaded on
  • Presentation posted in: General

Final Optic Research – Progress and Plans. M. S. Tillack. with contributions from :. Z. Dragojlovic, F. Hegeler, E. Hsieh, J. Mar, F. Najmabadi, J. Pulsifer, K. Sequoia, M. Wolford. HAPL Project Meeting, PPPL 27-28 October 2004. Overview. Final optic program summary

Download Presentation

M. S. Tillack

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


M s tillack

Final Optic Research – Progress and Plans

M. S. Tillack

with contributions from:

Z. Dragojlovic, F. Hegeler,

E. Hsieh, J. Mar, F. Najmabadi,

J. Pulsifer, K. Sequoia,

M. Wolford

HAPL Project Meeting, PPPL

27-28 October 2004


Overview

Overview

  • Final optic program summary

  • New mirror fabrication and testing

  • Larger scale testing

  • Contaminant transport modeling

  • Gas puff modeling


M s tillack

The steps to develop a final optic for a Laser IFE power plant (1 of 2)

1.“Front runner” final optic – Al coated SiC GIMM:

UV reflectivity, industrial base, radiation resistance

•Contamination•Optical quality•Fabrication•Radiation resistance

Key Issues:•Shallow angle stability•Laser damage resistancegoal = 5 J/cm2, 108 shots

  • 2. Characterize threats to mirror:

    • LIDT, radiation transport, contaminants

3. Perform research to explore damage mechanisms, lifetime and mitigation

Bonding/coating

Microstructure

Fatigue

Ion mitigation


The steps to develop a final optic for a laser ife power plant 2 of 2

The steps to develop a final optic for a Laser IFE power plant (2 of 2)

4. Verify durability through exposure experiments

10 Hz KrF laser

UCSD (LIDT)

XAPPER

LLNL (x-rays)

ion accelerator

neutron modeling and exposures

5.Develop fabrication techniques

and advanced concepts

6. Perform mid-scale testing


Diamond turned electroplated mirrors survived 10 5 shots at 18 j cm 2 on a small scale mm 2

Diamond-turned, electroplated mirrors survived 105 shots at 18 J/cm2 on a small scale (mm2)

  • Relatively small grains (10-20 mm)

  • Relatively dense, thick coating

Still, these mirrors ultimately fail due to grain motions, ...

... and we would like to improve the high-cycle fatigue behavior


M s tillack

35 mm “thick thin-film” mirror,turned at Schafer Corp. and exposed to 104 shots at 5 J/cm2

no damage to elecroplated mirror (turned at GA) under the same exposure conditions

Post-processing after thick (35-50 mm) thin-film deposition should provide good optical quality with a damage-resistant microstructure

rough substrate

polish/turn

coat

final polish/turn


Ringdown reflectometry now @266 nm indicates somewhat high absorption at 85

Ringdown reflectometry (now @266 nm) indicates somewhat high absorption at 85˚

reflectivity of 35 mm Schafer mirror


M s tillack

Diamond turning lines are too deep – 50 nm rms –

(A new Pacific Nanotechnolgy AFM has been added to our surface analysis capabilities)


M s tillack

Peaks grow during exposure (unlike earlier results which exhibited etching)

etching observed previously in diamond-turned polycrystalline foils


It s time to start making smoother mirrors

It’s time to start making smoother mirrors

MRF systems are popping up all over the place(this one is at Edmund Optics)


Larger mirrors are being fabricated with increasing emphasis on surface quality

Larger mirrors are being fabricated with increasing emphasis on surface quality

  • Other improvements under consideration

  • Mid-scale 4” optics

    • Thick e-beam coatings

    • Electroplated Al

• MRF surface finishing

• Hardening techniques

  • nanoprecipitate, solid solution hardening

  • friction stir burnishing (smaller grains)


Scaled testing was initiated at electra during late august

Scaled testing was initiated at Electra during late August

we spent 1 week assembling the optical path, developing test procedures, and exploring issues for large scale testing


Experimental layout

Beam Dump

UV Window

Wave Plate

Beam Profiler

Cube

Beam Sampler

Lens

Mirror

Window

Camera

43”

12”

Experimental Layout


Laser energy measurements showed dramatic energy loss along the beam path

Laser energy measurements showed dramatic energy loss along the beam path

Electra oscillator

2” graphite aperture

3” lead aperture

0.14 J to 5.2 J

(measured with a

2” calorimeter)

80 cm

periscope

10 cm

5.2 J

polarizer cubes

Nike

mirror

telescope

1/2

waveplate

3.9 J

p-polarized

10 cm

0.14 J

14.2 – 15.3 J

(measured with a

30 cm x 30 cm

calorimeter)

13.2 J

with a 2” dia.

aperture

12.8 J

(measured with a

30cm x 30 cm

calorimeter)

1” aperture

0.57 J

1.04 J

vacuum

chamber


We don t see this with our compex laser

1

3

4

5

6

2

7

8

1

2

3

4

We don’t see this with our Compex laser

1 = 86 mJ

2 = 84 mJ

3 = 86 mJ

4 = 85 mJ

1 = 228 mJ

2 = 119 mJ

3 = 95 mJ

4 = 92 mJ

5 = 13 mJ

6 = 75 mJ

7 = 58 mJ

8 = 56 mJ


M s tillack

An alternative idea for scaled testing:

large-aperture uncoated FS window @56˚

12” FS window($5250)

beam dump

700 J blunderbuss

34˚

30 cm squareaperture

10” roundaperture

10” diameter, 6-m fl Nike lens

6.7”

8” port

10”

30 cm

assume 700 J in 900 cm2 ~ 0.75 J/cm2

~25% of s-light reflected = 0.09 J/cm2

10” round on 6x12 rectangle ~ 362 cm2

35 Joules (polarized) available

chamber


Another alternative idea for scaled testing contrast is 100 1 over a 7 range

6”

12”

Another alternative idea for scaled testing:Contrast is >100:1 over a 7˚ range

10” diameter, 6-m fl Nike lens

beam dump

700 J blunderbuss

32˚

30 cm squarebeam with 9” round aperture

12” FS window

8” port

  • assume 700 J in 900 cm2 ~ 0.75 J/cm2

  • ~25% of s-light reflected = 0.09 J/cm2

  • 9” round ~ 410 cm2

  • 37 Joules (polarized) available

chamber


M s tillack

Contamination transport from the chamber to the final optic was explored using Spartan

  • 160 MJ NRL target

  • 50 mTorr Xe @RT

  • Bucky hand-off at 500 ms

Displacement field after 1st shot

  • Net flow toward chamber center is predicted

    • – we need to include rad-hydro displacements

  • Net flow toward optic?


M s tillack

Particles transport rapidly toward the

final optic

Test particle trajectories

Pressure at 100 ms

Pa

4

3

2

1

• We need to run multiple shots to establish the long-term behavior


M s tillack

Gas puffing was examined as a posssible optic protection technique

  • ~1 Torr-m may help reduce ion and x-ray damage

  • Fast gas puff could be used immediately preceding implosions

  • Might also help cool chamber gas


M s tillack

A gas puff sufficient to protect optics would increase the base pressure beyond 100 mTorr

Pump speed per duct1.5x105 l/s

Duct diameter75 cm

Duct length3 m

Number of ducts64

Orifice conductance44 l/s/cm2

Target mass4 mg

Rep rate5 Hz

Chamber radius7 m

It doesn’t look promising!


M s tillack

5-yr plan and progress to date

2001

2002

2003

2004

2005

2006

start

KrF

larger optics

Phase I evaluation

electroplatesuccess

initial promising results at 532 nm

new lab,cryopump

extended database,mid-scale testing,radiation damage, mirror quality, design integration

lower limits at 248 nm, chemistry control

attempts at thin film optics


  • Login