A5008876539- Laser Material Processing Techniques
- Advanced Surface Polishing Techniques
- Optical Coatings and Gratings
- Laser-Plasma Interactions and Diagnostics
- Surface Roughness and Optical Measurements
- Laser-induced spectroscopy and plasma
- Solid State Laser Technologies
- Laser Design and Applications
- Ocular and Laser Science Research
- Semiconductor materials and devices
- Metal and Thin Film Mechanics
- Diamond and Carbon-based Materials Research
- Nuclear Physics and Applications
- Particle accelerators and beam dynamics
- Integrated Circuits and Semiconductor Failure Analysis
- Optical Systems and Laser Technology
- High-pressure geophysics and materials
- Advanced Sensor Technologies Research
- Laser-Matter Interactions and Applications
- Advanced Optical Sensing Technologies
- Magnetic confinement fusion research
- Photorefractive and Nonlinear Optics
- High-Temperature Coating Behaviors
- X-ray Diffraction in Crystallography
- Radio Wave Propagation Studies
Sandia National Laboratories
2013-2025
Sandia National Laboratories California
2013-2020
University of New Mexico
2019
Lawrence Livermore National Laboratory
2019
Laser Zentrum Hannover
2019
Pacific Northwest National Laboratory
2019
University of Central Florida
2019
Bellingham Technical College
2018
Massachusetts Institute of Technology
2014
Pulsed power accelerators compress electrical energy in space and time to provide versatile experimental platforms for high density inertial confinement fusion science. The 80-TW “Z” pulsed facility at Sandia National Laboratories is the largest device world today. Z discharges up 22 MJ of stored its capacitor banks into a current pulse that rises 100 ns peaks as 30 MA low-inductance cylindrical targets. Considerable progress has been made over past 15 years use precision scientific tool....
Recent experiments on Sandia's Z facility have confirmed simulation predictions of dramatically reduced instability growth in solid metallic rods when thick dielectric coatings are used to mitigate density perturbations arising from an electrothermal instability. These results provide further evidence that the inherent surface roughness as a result target fabrication is not dominant seed for magneto-Rayleigh-Taylor instabilities liners with carefully machined smooth surfaces, but rather form...
Magnetized liner inertial fusion (MagLIF) experiments have demonstrated fusion-relevant ion temperatures up to 3.1 keV and thermonuclear production of 1.1 × 1013 deuterium–deuterium neutrons. This performance was enabled through platform development that provided increases in applied magnetic field, coupled preheat energy, drive current. Advanced coil designs with internal reinforcement an increase from 10 20 T. An improved laser pulse shape, beam smoothing, thinner entrance foils increased...
We report on a series of Magnetized Liner Inertial Fusion (MagLIF) experiments conducted the Z pulsed power facility that utilized high aspect ratio (ratio outer radius to wall thickness) liners with dielectric coatings and low-mix laser preheat configurations. The consisted an 10.6 beryllium tube coated 75 μm epoxy outside have been shown maintain better implosion stability than uncoated demonstrated consistent stagnation performances in previous [Ampleford et al., Phys. Plasmas 31, 022703...
This paper presents an analytic model for VLF and ELF atmospheric-noise amplitude-probability distributions (APDs). The APDs are governed by two parameters that can be determined at the receiver-one characterizing impulsivity of noise from local sources other ratio energy in impulsive-noise component to non-impulsive background-noise component. derived expression explicitly shows dependence APD on earth-ionosphere-waveguide propagation constant. Calculated presented ambient nominally...
High-reflection coatings with broad bandwidth can be achieved by pairing a low refractive index material, such as SiO2, high TiO2. To achieve index, absorption TiO2 films, we optimized the reactive, ion-assisted deposition process (O2 levels, rate, and ion beam settings) using e-beam evaporated Ti. high-index layers were then paired SiO2 low-index in quarter-wave-type coating to broader high-reflection compared same composed of HfO2/SiO2 layer pairs. However, improved exhibited TiO2/SiO2 is...
The Z-Backlighter Laser Facility at Sandia National Laboratories was developed to enable high energy density physics experiments in conjunction with the Z Pulsed Power Laboratories, an emphasis on backlighting. Since first laser system there became operational 2001, facility has continually evolved add new capability and missions. currently several systems including nanosecond/multi-kilojoule Z-Beamlet (ZBL), sub-picosecond/kilojoule- class Z-Petawatt (ZPW) Laser, smaller nanosecond/100...
We have examined how three different cleaning processes affect the laser-induced damage threshold (LIDT) of antireflection coatings for large dimension, Z-Backlighter laser optics at Sandia National Laboratories. Laser thresholds were measured after created, and again 4 months later to determine which most effective. Coatings that received exhibited highest LIDTs compared not cleaned. In some cases, there is nearly a twofold increase in LIDT between cleaned uncleaned (19.4 J/cm2 39.1 J/cm2)....
X-ray diffraction measurements to characterize phase transitions of dynamically compressed high-Z matter at Mbar pressures require both sufficient photon energy and fluence create data with high fidelity in a single shot. Large-scale laser systems can be used generate x-ray sources above 10 keV utilizing line radiation mid-Z elements. However, the laser-to-x-ray conversion efficiency these energies is low, thermal x-rays or hot electrons result unwanted background. We employ polycapillary...
Broad bandwidth coatings allow angle of incidence flexibility and accommodate spectral shifts due to aging water absorption. Higher refractive index materials in optical coatings, such as TiO2, Nb2O5, Ta2O5, can be used achieve broader bandwidths compared that contain HfO2 high layers. We have identified the deposition settings lead highest index, lowest absorption layers via e-beam evaporation using ion-assisted deposition. paired these with SiO2 low material create broad reflection...
The laser damage thresholds of optical coatings can degrade over time due to a variety factors, including contamination and aging. Optical deposited using electron beam evaporation are particularly susceptible degradation their porous structure. In previous study, the were reduced by roughly factor 2 from years 2013 2017. in question high reflectors for 1054 nm that contained SiO<sub>2</sub> HfO<sub>2</sub> and/or TiO<sub>2</sub> layers, they stored sealed PETG containers class 100 clean...
We designed an optical coating based on TiO2/SiO2 layer pairs for broad bandwidth high reflection (BBHR) at 45-deg angle of incidence (AOI), P polarization femtosecond (fs) laser pulses 900-nm center wavelength, and produced the coatings in Sandia's large optics coater by reactive, ion-assisted e-beam evaporation. This paper reports laser-induced damage threshold (LIDT) tests these coatings. The HR bands BBHR pose challenges to LIDT tests. An ideal test would be a vacuum environment...
We have designed a dichroic beam combiner coating consisting of 11 HfO<sub>2</sub>/SiO<sub>2</sub> layer pairs deposited on large fused silica substrate. The provides high transmission (HT) at 527 nm and reflection (HR) 1054 for light 22.5° angle incidence (AOI) in air S polarization (Spol). coating's design is based layers near half-wave optical thickness the space stable HT nm, with modifications that provide HR while preserving nm. Its implementation nm/1054 dual wavelength...
We report the design, fabrication, and characterization of miniaturized, flush-mounted Langmuir probe arrays for RF diagnosis plasmas in HF to microwave range frequencies.We developed probes radii ≥125 µm by electroless nickel metallization ultrasonically drilled through-substrate vias.Planar with as many 25 spaced 1.6 mm apart (39 probes/cm 2 ) Pyrex, silicon carbide, alumina substrates were produced.The sensor system was built have a frequency response between MHz 3 GHz, impedance greater...
We designed a dichroic beam combiner coating with 11 HfO2/SiO2 layer pairs and deposited it on large substrate. It provides high transmission (HT) at 527 nm reflection (HR) 1054 for 22.5-deg angle of incidence (AOI), S polarization (Spol), uses near half-wave thicknesses HT nm, modified HR nm. The two options the each require that intensity be incident from within substrate (from glass). analyze laser-induced damage threshold (LIDT) differences between in terms 527- 1054-nm E-field behaviors...
We designed and produced optical coatings for broad bandwidth high reflection (BBHR) of femtosecond (fs) pulses energy petawatt (PW) lasers. These BBHR consist TiO<sub>2</sub>/SiO<sub>2</sub> and/or HfO<sub>2</sub>/SiO<sub>2</sub> layer pairs formed by reactive E-beam evaporation with ion-assisted deposition in Sandia's Large Optics Coating Facility. Specifications the HR band center wavelength are 45° angle incidence (AOI), P polarization (Ppol), use at different AOIs humid or...
When an optical coating is damaged, deposited incorrectly, or otherwise unsuitable, the conventional method to restore optic often entails repolishing surface, which can incur a large cost and long lead time. We propose three alternative options repolishing, including (i) burying unsuitable under another coating, (ii) using ion milling etch completely from surface then recoating optic, (iii) through number of layers, leaving rest intact, layers that were etched. Repairs made on test optics...
We have designed and produced an optical coating suitable for broad bandwidth high reflection (BBHR) at 45° angle of incidence (AOI), P polarization (Ppol) petawatt (PW) class fs laser pulses ~ 900 nm center wavelength. such BBHR coatings consisting TiO<sub>2</sub>/SiO<sub>2</sub> layer pairs deposited by ion assisted e-beam evaporation using the large optics coater Sandia National Laboratories. This paper focuses on laser-induced damage threshold (LIDT) tests these coatings. LIDT is...
Dichroic coatings have been developed for high transmission at 527 nm and reflection 1054 laser operations in the nanosecond pulse regime. The consist of HfO<sub>2</sub> SiO<sub>2</sub> layers deposited with e-beam evaporation, laser-induced damage thresholds as 12.5 J/cm<sup>2</sup> were measured 532 3.5 ns pulses (22.5 degrees angle incidence, S-polarization). However, measurements single wavelength do not adequately characterize resistance these coatings, since they designed to operate...
Solutions of the one- and two-dimensional integral equations that describe ground wave propagation are presented compared. The one-dimensional equation is shown to be inaccurate at low frequencies for obstacles narrower than about 10 km typical pathlengths. In such cases, needed account properly signal's dependence on obstacle width, recovery long distances, transverse diffraction pattern. solutions approach each other large distances beyond very wide obstacles.
We develop and characterize high index of refraction thin films by e-beam evaporation Ti3O5, Ta2O5 Nb2O5 in reactive, ion-assisted deposition processes. then deposit broad bandwidth reflection (HR) coatings based on quarter-wave stacks these layers alternating with SiO2 low layers. The HR band is centered at 1054 nm designed for 45o angle incidence. compare the laser induced damage thresholds order to explore tradeoffs between their properties bandwidths.
Optical coatings deposited using electron beam evaporation are subject to aging effects that change the spectral characteristics of optical coating. The aim this study was determine whether can also negatively impact laser damage resistance an Maintaining high is particularly important for performance fluence systems. In 2013, we different reflection 1054 nm containing HfO<sub>2</sub>/TiO<sub>2</sub>/SiO<sub>2</sub> layers. For study, re-measured thresholds these at 3.5 ns if cause threshold...
Optical coatings with the highest laser damage thresholds rely on clean conditions in vacuum chamber during coating deposition process. A low-base pressure chamber, as well ability of system to maintain required deposition, are important aspects limiting amount defects an optical that could induce damage. Our large optics at Sandia National Laboratories normally relies three cryo pumps low pressures for e-beam processes. However, occasion, one or more have been out commission. In light this...