Linn Van Woerkom The Ohio State University

1. Laser-Matter Interactions at SCARLETScience Center for Advanced Research on Lasers & Engineered Targets Linn Van Woerkom The Ohio State University Presented at the Fast Ignition Workshop 05 November 2006

2. Goal • Develop techniques/protocols for the new generation of rep-rated Petwatt-class lasers • Targets  mass production & insertion • Diagnostics • Data management • Thus enabling systematic studies of ultraintense laser-matter interactions • With ultimate GOAL of providing test-bed infrastructure for developing point designs for Fast Igniton

3. We are NOT ….. building a big, bad laser …..

4. Why Another Center? • Currently there are many 20 – 200 TW lasers • Many laser-matter processes studied • Limitations due to low duty cycle • Need better statistics & reproducibility • Eventually need power plant • Solution  Build high rep rate petawatt lasers • Problem  What to do w/ rep-rated Petawatt laser? • What about targets? • current targets ~$1-5k each  at 1 Hz that hurts • Need mass production • What about diagnostics • Currently film packs used for many diagnostics • What about data collection?  high data rates

5. The Team • The Ohio State University • PI’s  L. Van Woerkom & R. Freeman • Optics & diagnostics  Dr. Enam Chowdhury • Facility & Integration  John Marketon • General Atomics • PI  R. Stephens • Design  Neil Alexander + others • Targeting collaboration with CLF at RAL, UK

6. The Place • Nuclear Physics Van de Graaff Facility • ~10,000 ft2 total • ~3000 ft2 High bay • Lots of electrical • Renovations in initial design phase

7. The Place II

8. The New Place

9. The Plan • Now  parallel efforts • OSU purchases 20 TW system • 20 fs, 400 mJ, 10 pps Ti:S commercial system • OSU renovates Van de Graaff building • OSU develops rep-rated diagnostics • OSU develops data management systems • GA designs & builds prototype target carrier • Test at LLNL and/or others • Work with target designers at RAL, UK • Move into new facility July 2008 • Upgrade laser to 250 – 1000 TW

10. Need Systematic Studies Real Progress  reproducible data  rep-rated systems • To explore efficiencies • Laser-electron  front surface morphology • Laser-proton  rear surface morphology • To understand relativistic charge transport • Surface fields & resistivity • Transport in dense plasmas • To develop diagnostic abilities • Transfer technology to large facilities On the road to a real point design …..

11. Requirements • 0.1 – 1.0 Petawatt Peak Power • PRR  10 shots/hour scaleable to Hz level • Two short pulse beams • Automated target insertion & alignment • Automated focus correction on each shot • Reasonable contrast ratio • Highly diagnosed laser record of each shot • Modular architecture  if $ stops we don’t

12. 20 TW - Phase I Commercial System 200 TW – Phase II ~2009 1-3 PW – Phase III (dreams are free) 20 fs, 400 mJ, 10 pps Ti:S Front End 20 fs, 4J, 10 pps Ti:S amplifier 20 fs, 20J, 1 pps Ti:S amplifier Concept Schematic • Thermal loading issues • Need to load w/o amplifying • Feedback to adaptive optics • Scaleable to higher PRR Rep-rated diagnostics diagnostic diagnostic diagnostic diagnostic Rapid target insertion • target must align to diagnostics • laser must align to target Adaptive optics

13. Power & Energy Issues • Must produce peak focused intensities in the range of • Use ultrashort pulses  25 – 35 fs • At 25 fs • 1 PW  25 J/pulse • 40-50 J before compression • ~100-200 J/pulse pump energy for Ti:S

14. Pulse Repetition Rate Issues • Start “easy”  minutes between shots • We need the time for target manipulation • Scale later to hertz-ish rates • Solve problems along the way to higher PRR

15. Alignment Procedure Issues • Diagnostics  fixed point in space • How do we make it & find it? • Align target to diagnostic center • How to align rep-rated targets? • Align laser to target • straightforward using industrial technology? • Maintain optimal focal properties • How do we move focus w/o destroying focus?

16. Target Insertion Issues • Must handle 10 shots/hour & scale to faster • Run several hours w/o venting target chamber • Handle complex targets • Multilayers • Cones • Structures • Must be economical!!?? • Align target to diagnostic center • Use industrial machine vision • Advanced image processing • Protect subsequent targets • Radiation issues? • Debris issues

17. Target Fabrication

18. Metrology & SCARLET Positioner • A transfer standard is passed between the systems • A reference target (e.g. a rigidly mounted cube) is put in the Metrology Station • Its center and orientation are noted SCARLET CHAMBER Fiducial cameras (orthogonal) METROLOGY STATION Target camera and lens (orthogonal) Hexapod: Alio Industries Fiducial cameras (orthogonal) Target Fiducial lasers (orthogonal) Fiducial lasers (orthogonal) Hexapod Positioner Hexapod Positioner

19. The Hexapod High Vacuum Version Hexapod for Prototype Hexapods made by Alio industries

20. Target System Target Elevator Hexapod Optical table leg Vacuum chamber jacket around leg Attachment port for target magazine

21. Target Handling Target Manipulator shaft Target Elevator Target Assemblies will get dropped of here (tube will surround hexapod, shown here offset Target Alignment Tube and receptacle attach to hexapod here Hexapod

22. Alignment Issues • Diagnostics bolt onto fixed chamber • Must maximize solid-angle real estate • Some diagnostics use collection optics • Ka & XUV • Can we move the collection optic and align to the target? • What about laser pointing stability? • Must be “Titan-like” and then better know everything about everything on EVERY shot  AT HIGH REP-RATE

23. Conclusions • SCARLET at OSU  laser-target facility • Look at rep-rated system issues • Targets • Diagnostics • Data Management • Goal is to develop the infrastructure for rep-rated HEDP • We have the building • Design in progress • Phase I – Target Insertions + 20 TW laser ~Summer ‘08 • GA designing targets & carriers & metrology • Technology transferred to other facilities