Alexei Yu. Kuznetsov 1, Vitali B. Prakapenka 1, Andrew J. Campbell 2, Thomas S. Duffy 3, Guoyin Shen 4, Dion L. Heinz 1, Mark L. Rivers 1, Stephen R. Sutton 1 1 University of Chicago, Chicago, Illinois 60637, USA 2 University of Maryland, College Park, MD Princeton University, Princeton, NJ Carnegie Institution of Washington, 9700 South Cass Ave, Argonne, IL A New CO 2 Laser Heating System at GSECARS: A COMPRES Infrastructure Development Project

Acknowledge GSECARS stuff: Mark Rivers Steve Sutton Yanbin Wang Vitali Prakapenka Peter Eng Sanjit Ghose Matt Newville Atsushi Kubo Takeyuki Sanehira Nancy Lazarz Mike Jagger Fred Sopron Clayton Pullins Charlie Smith Przemek Dera COMPRES

Synopsis 1.Introduction - Current status of the project and further plans - Current status of the project and further plans - CO 2 laser heating: main goal - CO 2 laser heating: main goal 2.CO 2 laser heating system - Key design considerations - Main characteristics - Main characteristics - Key problems - Concept of the setup 3.Conclusion remarks

Introduction Current status of the project installation of the CO 2 laser heating system in the ID-D station installation of the CO 2 laser heating system in the ID-D station Next steps commissioning of the system commissioning with local proposals open to general users

Introduction CO 2 laser =10.6  m YAG, YLF, Fiber lasers ~ 1  m Laboratory Astrophysics Group of the AIU Jena: jena.de/Laboratory/OCDB/index.html Jan L. C. Wijers, Technische Rundschau, Bern TR Transfer nr F. Kemper et al. Nature 415 (2002), 295

CO 2 laser heating system Key design consideration  Integrated into existing NIR (~1  m wavelength) laser heating setup  Compact design  Power stability and control  Quick switch between the NIR and CO 2 laser heating  IR (~10  m) sample alignment  Monitoring of the heating process (IR, Vis)  Full remote control and user friendly operation  Safety

CO 2 laser: main characteristics Synrad f201 laser Wavelength  m Power output200 W (CW), 250 W (PWM) Mode qualityTEM 00, 98% purity PolarizationLinear, horizontal Beam diameter4.5 mm (at laser output) Beam divergence4.0 mrad

CO 2 laser heating system: key problems Power stability and power control Pulsed width modulation command signal waveform Polarizer-Analyzer- Attenuator (Brewster windows)

CO 2 laser heating system: key problems Sample alignment is a key issue in a successful HP experiment 1. Chromatic effect Problems of using visible wavelength range: 2. Heating process is visible only when sample is starting to emit the light (T ~1500K) Imaging in ~ 10  m > 1

CO 2 laser heating system: key problems Switch between NIR and CO 2 laser heating Silver based coating Reflects ~98% of the light at both wavelengths

CO 2 laser heating system General scheme Beam splitter

What do IR images look like? Magnified images of the wire 300  m (a) Back illuminated by IR light (b) 300  m Heated to 450 o C Trade-off between magnification and image quality Diffraction at 3 um Magnification 11 No Diffraction Raw Image Magnification 11 Diffraction at 10.6 um Magnification 11 Diffraction at 10.6 um Magnification 4 Simulated by David Koren, II-VI Infrared.

What do IR images look like? 300  m Sample in the DAC

Conclusion remarks  The combination of a synchrotron X-ray source with a laser- heated DAC has been providing important results and new discoveries in high pressure mineral physics  Comprehensive laser heating setup is one of the important components defining versatility of high-pressure / high- temperature studies at GSECARS

Welcome to GSECARS Beamlines!

Temperature measurements Planck’s law Optics correction Emissivity correction Emissivity model - fitting parameters - adjustable parameter

Spot size of the focused laser beam