Linn Van Woerkom The Ohio State University
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Transcript of Linn Van Woerkom The Ohio State University
Laser-Matter Interactions at Laser-Matter Interactions at SCARLETSCARLET
Science Center for Advanced Research on Science Center for Advanced Research on
Lasers & Engineered TargetsLasers & Engineered Targets
Linn Van WoerkomLinn Van WoerkomThe Ohio State UniversityThe Ohio State University
Presented at the Fast Ignition Workshop05 November 200605 November 2006
GoalGoal
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 Thus enabling systematic studies of ultraintense laser-matter interactionsultraintense laser-matter interactions
With ultimate GOAL of providing test-bed With ultimate GOAL of providing test-bed infrastructure for developing point designs infrastructure for developing point designs for Fast Ignitonfor Fast Igniton
We are NOT …..We are NOT …..
building a big, bad laser …..building a big, bad laser …..
Why Another Center?Why Another Center?
Currently there are many 20 – 200 TW lasersCurrently there are many 20 – 200 TW lasersMany laser-matter processes studiedMany laser-matter processes studiedLimitations due to low duty cycleLimitations due to low duty cycle– Need better statistics & reproducibilityNeed better statistics & reproducibility– Eventually need power plantEventually need power plant
Solution Solution Build high rep rate petawatt lasers Build high rep rate petawatt lasersProblem Problem What to do w/ rep-rated Petawatt laser? What to do w/ rep-rated Petawatt laser? What about targets?What about targets?– current targets ~$1-5k each current targets ~$1-5k each at 1 Hz that hurts at 1 Hz that hurts– Need mass productionNeed mass production
What about diagnosticsWhat about diagnostics– Currently film packs used for many diagnosticsCurrently film packs used for many diagnostics
What about data collection? What about data collection? high data rates high data rates
The TeamThe Team
The Ohio State UniversityThe Ohio State University– PI’s PI’s L. Van Woerkom & R. Freeman L. Van Woerkom & R. Freeman– Optics & diagnostics Optics & diagnostics Dr. Enam Chowdhury Dr. Enam Chowdhury– Facility & Integration Facility & Integration John Marketon John Marketon
General AtomicsGeneral Atomics– PI PI R. Stephens R. Stephens– Design Design Neil Alexander + others Neil Alexander + others
Targeting collaboration with CLF at RAL, UKTargeting collaboration with CLF at RAL, UK
The PlaceThe Place
Nuclear Physics Van de Graaff FacilityNuclear Physics Van de Graaff Facility
• ~10,000 ft~10,000 ft22 total total• ~3000 ft~3000 ft22 High bay High bay• Lots of electricalLots of electrical• Renovations in initial Renovations in initial
design phasedesign phase
The Place IIThe Place II
The New PlaceThe New Place
The PlanThe Plan
Now Now parallel efforts parallel efforts– OSU purchases 20 TW systemOSU purchases 20 TW system
20 fs, 400 mJ, 10 pps Ti:S commercial system20 fs, 400 mJ, 10 pps Ti:S commercial system
– OSU renovates Van de Graaff buildingOSU renovates Van de Graaff building– OSU develops rep-rated diagnosticsOSU develops rep-rated diagnostics– OSU develops data management systemsOSU develops data management systems– GA designs & builds prototype target carrierGA designs & builds prototype target carrier
Test at LLNL and/or othersTest at LLNL and/or othersWork with target designers at RAL, UKWork with target designers at RAL, UK
Move into new facility July 2008Move into new facility July 2008– Upgrade laser to 250 – 1000 TWUpgrade laser to 250 – 1000 TW
Need Systematic StudiesNeed Systematic Studies
To explore efficienciesTo explore efficiencies– Laser-electron Laser-electron front surface morphology front surface morphology– Laser-proton Laser-proton rear surface morphology rear surface morphology
To understand relativistic charge transportTo understand relativistic charge transport– Surface fields & resistivitySurface fields & resistivity– Transport in dense plasmasTransport in dense plasmas
To develop diagnostic abilitiesTo develop diagnostic abilities– Transfer technology to large facilitiesTransfer technology to large facilities
On the road to a real point design …..
Real Progress reproducible data rep-rated systems
RequirementsRequirements
0.1 – 1.0 Petawatt Peak Power0.1 – 1.0 Petawatt Peak Power
PRR PRR 10 shots/hour scaleable to Hz level 10 shots/hour scaleable to Hz level
Two short pulse beamsTwo short pulse beams
Automated target insertion & alignmentAutomated target insertion & alignment
Automated focus correction on each shotAutomated focus correction on each shot
Reasonable contrast ratioReasonable contrast ratio
Highly diagnosed laser record of each shotHighly diagnosed laser record of each shot
Modular architecture Modular architecture if $ stops we don’t if $ stops we don’t
810 :1
Concept SchematicConcept Schematic
20 fs, 400 mJ, 10 pps Ti:S Front End
20 TW - Phase ICommercial System
20 fs, 4J, 10 pps Ti:S amplifier
200 TW – Phase II~2009
• Thermal loading issues• Need to load w/o amplifying• Feedback to adaptive optics• Scaleable to higher PRR
Adaptive optics
diagnosticdiagnosti
cdiagnostic
diagnostic
• target must align to diagnostics• laser must align to target
20 fs, 20J, 1 pps Ti:S amplifier
1-3 PW – Phase III(dreams are free)
Rapid target insertion
Rep-rateddiagnostics
Must produce peak focused intensities in the Must produce peak focused intensities in the range of range of
Use ultrashort pulses Use ultrashort pulses 25 – 35 fs 25 – 35 fs
At 25 fs At 25 fs – 1 PW 1 PW 25 J/pulse 25 J/pulse
40-50 J before compression40-50 J before compression
~100-200 J/pulse pump energy for Ti:S~100-200 J/pulse pump energy for Ti:S
Power & Energy IssuesPower & Energy Issues
19 21 210 10 /W cm
Pulse Repetition Rate IssuesPulse Repetition Rate Issues
Start “easy” Start “easy” minutes between shots minutes between shots– We need the time for target manipulationWe need the time for target manipulation– Scale later to hertz-ish ratesScale later to hertz-ish rates
Solve problems along the way to higher Solve problems along the way to higher PRRPRR
Alignment Procedure IssuesAlignment Procedure Issues
Diagnostics Diagnostics fixed point in space fixed point in space– How do we make it & find it?How do we make it & find it?
Align target to diagnostic centerAlign target to diagnostic center– How to align rep-rated targets?How to align rep-rated targets?
Align laser to targetAlign laser to target– straightforward using industrial technology?straightforward using industrial technology?
Maintain optimal focal propertiesMaintain optimal focal properties– How do we move focus w/o destroying focus?How do we move focus w/o destroying focus?
Target Insertion IssuesTarget Insertion Issues
Must handle 10 shots/hour & scale to fasterMust handle 10 shots/hour & scale to fasterRun several hours w/o venting target chamber Run several hours w/o venting target chamber Handle complex targetsHandle complex targets– MultilayersMultilayers– ConesCones– StructuresStructures
Must be economical!!??Must be economical!!??Align target to diagnostic centerAlign target to diagnostic center– Use industrial machine visionUse industrial machine vision– Advanced image processingAdvanced image processing
Protect subsequent targetsProtect subsequent targets– Radiation issues?Radiation issues?– Debris issuesDebris issues
Target FabricationTarget Fabrication
Metrology & SCARLET PositionerMetrology & SCARLET Positioner
A transfer standard is passed between the systemsA transfer standard is passed between the systemsA reference target (e.g. a rigidly mounted cube) is put in A reference target (e.g. a rigidly mounted cube) is put in the Metrology Stationthe Metrology Station– Its center and orientation are notedIts center and orientation are noted
Fiducial lasers (orthogonal)
Fiducial cameras (orthogonal)
Hexapod Positioner
Fiducial lasers (orthogonal)
Fiducial cameras (orthogonal)
Hexapod Positioner
Target
Target camera and lens (orthogonal)
SCARLET CHAMBERMETROLOGY STATION
Hexapod: Alio
Industries
The HexapodThe Hexapod
Hexapod for Prototype High Vacuum Version
Hexapods made by Alio industries
Target SystemTarget System
Attachment port for target magazine
Optical table legVacuum chamber jacket around leg
Target Elevator
Hexapod
Target HandlingTarget Handling
Target Elevator
Target Manipulator shaft
Hexapod
Target Alignment Tube and receptacle attach to hexapod here
Target Assemblies will get dropped of here(tube will surround hexapod, shown here offset
Alignment IssuesAlignment Issues
Diagnostics bolt onto fixed chamberDiagnostics bolt onto fixed chamber
Must maximize solid-angle real estateMust maximize solid-angle real estate
Some diagnostics use collection opticsSome diagnostics use collection optics– KK & XUV & XUV
– Can we move the collection optic and align to Can we move the collection optic and align to the target?the target?
What about laser pointing stability?What about laser pointing stability?– Must be “Titan-like” and then betterMust be “Titan-like” and then better
know everything about everything on EVERY shot AT HIGH REP-RATE
ConclusionsConclusions
SCARLET at OSU SCARLET at OSU laser-target facility laser-target facility– Look at rep-rated system issuesLook at rep-rated system issues
TargetsTargets
DiagnosticsDiagnostics
Data ManagementData Management
– Goal is to develop the infrastructure for rep-rated HEDPGoal is to develop the infrastructure for rep-rated HEDP
We have the buildingWe have the building– Design in progressDesign in progress– Phase I – Target Insertions + 20 TW laser ~Summer ‘08Phase I – Target Insertions + 20 TW laser ~Summer ‘08
GA designing targets & carriers & metrologyGA designing targets & carriers & metrology
Technology transferred to other facilitiesTechnology transferred to other facilities