1. XAPPER Capabilities, Progress & Plans Presented by: Jeff Latkowski XAPPER Team: Ryan Abbott, Brad Bell, and Keith Kanz May 16, 2006 Work performed under the auspices of the U. S. Department of Energy by Lawrence Livermore National Laboratory under Contract W-7405-Eng-48.

2. XAPPER JFL 05/16/06 Outline Current capabilities Progress since the ORNL HAPL meeting Planned improvements

3. XAPPER JFL 05/16/06 Unexposed Using our first high-quality ellipsoidal condenser, pure tungsten can be damaged 9000 pulses @ ~1.5 J/cm 2 Significant damage is observed at a fluence of ~1.5 J/cm 2

4. XAPPER JFL 05/16/06 Tungsten test matrix: 10,000 shots on powder met. 1.2 J/cm 2 ~1.5 J/cm 2

5. XAPPER JFL 05/16/06 Current capabilities Soft x-ray source: Fluences of 0.25-1.25 J/cm 2 (  ~ 10%) ~50 ns 10-90% risetime FWHM spot size is ~400  m Repetition rates ≤10 Hz 10 6 pulses demonstrated, 10 5 pulse routine Operational: Fluence measurement conducted using CCD (or CMOS) camera in conjunction with calorimeter Vacuum typically ~10 -4 torr, then inject xenon for pinch and come up to ~3 mtorr Samples actively heated up to 1000ºC (no active cooling) Other diagnostics and analysis equipment: In-chamber sample imaging (low magnification) X-ray spectrometer Photodiodes (fast and integrating) PIE: SEM, TEM, Veeco, x-ray radiography, optical microscopy ~1.0 J/cm 2 needed to heat 600  C sample to peak surface temperature of 2500  C

6. XAPPER JFL 05/16/06 Since the ORNL HAPL meeting, we have finalized our pyrometer design Wavelengths of 0.6, 0.8, 1.0, 1.2, 1.4 and 1.6  m selected Using Avalanche Photodiodes (APDs): Si APDs at 0.6, 0.8 and 1.0  m InGaAs APDs at 1.2, 1.4 and 1.6  m Each will be integrated into an amplifier Able to reuse SiO 2 fiber and feedthru from UCSD thermometer Pyrometer head design uses 3 optics (63, -40 and 63 mm focal length) and is 98.9mm long; 100  m field-of-view 1600 nm 1000nm 800 nm 600nm 500-1700nm 1400nm 1200 nm

7. XAPPER JFL 05/16/06 Calibration will be a big part of our pyrometer effort Emissivity is both wavelength and temperature dependent Past work has assumed that  ( 1 ) =  ( 2 ) Okay assumption when operating at 0.7, 0.8  m Not a reasonable assumption for a wide range of wavelengths We would see ~2x variation in  over our wavelengths of 0.6-1.6  m Emissivity ratios are not constant with temperature Data for polished single crystal tungsten.

8. XAPPER JFL 05/16/06 Calibration, (Cont'd.) To enable calibration, we are procuring a high-temperature sample heater (2500  C) Measurements will be taken on the same sample with the pyrometer head sitting in the same orientation to the actual measurement (other than the direction of gravity) Calibration measurements will be taken every 100  C from 1500-2500  C Post-processing will be used to determine temperature vs. time from the 6-channel data

9. XAPPER JFL 05/16/06 Calibration, (Cont'd.) HeatWave, Inc. is building the sample furnace: Will mount to an 8” conflat Water-cooled flange 5-mm-diameter portion of sample viewable at 45  (Very) hot test slated for end of June

10. XAPPER JFL 05/16/06 With the exception of the common optics and minor items all parts are on order Ordered: Sample furnace Bandpass filters (2 have arrived and exceed specifications) Longpass filters (to be used as dichroics) Si and InGaAs APDs To be ordered soon: Optical breadboard Overall enclosure Optical mounts and tubes BK7/SiO 2 lenses Batteries (for detectors) To be fabricated: Light-tight enclosure for detectors (with filter mounts) Top & bottom plates for calibration chamber (in progress) Arrived/Available: Signal cabling Oscilloscopes Optical fiber & feedthru We are on schedule for system assembly / checkout in early-July

11. XAPPER JFL 05/16/06 Other progress and/or improvements We have completed a forward model of the pyrometer system, including tungsten emission vs. and T, optical losses, and detector response We have assembled a system to use as the calibration chamber We are beginning to write procedures for the calibration furnace Our safety paperwork is being updated We are beginning to write the pyrometer data processing software We have refined our CCD processing software (used to determine x-ray fluence) to account for path-dependent filter attenuation Future exposure campaigns will include mass loss measurements (does this preclude us from putting multiple spots on a sample?)

12. XAPPER JFL 05/16/06 Summary Since the last HAPL meeting, we have worked hard to design and procure the new pyrometer: We expect to bring the pyrometer operational in July We expect to have new sample exposures, with measured temperatures, in time for the next HAPL meeting Planned sample priority is: (1) single crystal, (2) VPS tungsten, and (3) powder met. tungsten, (4) silicon carbide We are holding off (for now) on the fabrication of a new ellipsoidal optic for use on XAPPER that would enable exposure of optical materials (low , big spot) Right priority?

13. Back-up slides

14. XAPPER JFL 05/16/06 The original thermometer has not worked for us for a variety of reasons Original system used 200  m fiber with 75 and 40 mm lenses: Gave a 375  m diameter field of view XAPPER has a small spot size of ~440  m diameter Gave temperature variations in field of view (a definite no-no for optical pyrometry) Switched optics to 62 and 150 mm lenses: Field of view reduced to 83  m Increased edge temperature to 2450 ºC Reduced field of view cuts signal by 20x, but 46% more solid-angle Overall signal reduction of 14x

15. XAPPER JFL 05/16/06 Original thermometer, (Cont'd.) Aligning the laser spot to the focused x-ray beam was impossible without manipulation under vacuum  installed two-axis motorized gimbal system Found a signal! Much celebration! Movie shows field of view with old thermometer head

16. XAPPER JFL 05/16/06 Original thermometer, (Cont'd.) We moved onto a new sample to start collecting real data  signal was gone! Discovered that the heavily damaged sample had been reflecting pinch light into the thermometer head Confirming experiment: blocked EUV beam with a plate of glass and still saw same (visible light) signal 

17. XAPPER JFL 05/16/06 We have tried various fixes Look for a dead-zone in the spectrum  doesn't appear to be one Temporal discrimination between pinch and emitted light  pinch light persists too long Vary angles  not a real option (can’t get shallower angle; blackbody emission is lambertian, so signal would fall rapidly at steeper angles) Look at the back side of a thin sample  inadequate space All of these options assume that we have a good signal that gets drowned out by reflected pinch light. Instead, we see nothing until the material damages. Suppressing the pinch light won’t fix the underlying problem.

18. XAPPER JFL 05/16/06 Original thermometer, (Cont'd.) 10 -9 10 -7 10 -5 10 -3 10 -1 3500 3000 2500 2000 1500 1000 Use thin sample (<5  m) to keep material hot for "long" time (milliseconds): Sit at lower temperature, lose by T 4 (12-18x) Able to count for ~1ms instead of ~100ns, win big (10 4 x) Unfortunately, the ripples inherent to a thin foil are quite similar to those resulting from surface damage  we immediately see reflected pinch light

19. XAPPER JFL 05/16/06 Original thermometer, (Cont'd.) Why doesn’t it work for us? Signal strength is just too low: 700/800nm aren’t the best wavelengths for our target temperatures; plus, small spread forces narrow bandpass (10 vs. 40nm) filters, further reducing the possible signal Simple analysis shows that blackbody emission getting to thermometer head (with Lambertian distribution) is only 1400-2100 p/ns in each band Emissivity probably ~0.3 and filters transmission is ~50%, so we have 200-300 p/ns Uncoated fiber ends (and possibly optics) result in further reductions

20. XAPPER JFL 05/16/06 Source designed / built by PLEX LLC Operates with xenon gas pinch to produce 80-150 eV x-rays Operation possible at up to 10 Hz for millions of pulses Condensing optic Material sample Plasma pinch The XAPPER experiment is used to study damage from rep-rated x-ray exposure