A5085332037- Atomic and Molecular Physics
- Laser-induced spectroscopy and plasma
- Magnetic confinement fusion research
- Solar and Space Plasma Dynamics
- Stellar, planetary, and galactic studies
- X-ray Spectroscopy and Fluorescence Analysis
- Ionosphere and magnetosphere dynamics
- Photocathodes and Microchannel Plates
- Astrophysical Phenomena and Observations
- Astronomical Observations and Instrumentation
- Atmospheric Ozone and Climate
- Electron and X-Ray Spectroscopy Techniques
- Astro and Planetary Science
- Nuclear Physics and Applications
- Fusion materials and technologies
- Mass Spectrometry Techniques and Applications
- Astronomy and Astrophysical Research
- Scientific Measurement and Uncertainty Evaluation
- Geomagnetism and Paleomagnetism Studies
- Calibration and Measurement Techniques
- Nuclear physics research studies
- Particle Accelerators and Free-Electron Lasers
- Advanced Chemical Physics Studies
- Scientific Research and Discoveries
- Botany, Ecology, and Taxonomy Studies
University of California, Berkeley
2013-2025
Cheetah Conservation Fund
2023-2024
Lawrence Livermore National Laboratory
2009-2017
Princeton Plasma Physics Laboratory
2017
Space Science Institute
2010
Center for Astrophysics Harvard & Smithsonian
2009
Universidad Nacional Autónoma de México
2000
University of Hawaiʻi at Mānoa
1996
We present high-resolution laboratory measurements of the emission from various ions C, N, O, F, Ne, S, Ar, Fe, and Ni in extreme ultraviolet wavelength band centered around λ211 Fe xiv channel Atmospheric Imaging Assembly on Solar Dynamics Observatory. While all strong iron lines this region are well known, we note many weaker that not yet identified. The high resolution our also allows us to resolve several xi, xii, xiii between 200 205 Å, whose identities were question based a...
Using a high-resolution grating spectrometer on the Livermore EBIT-I electron beam ion trap, we have measured three n=3,4→n=1 K-shell emission lines in lithium-like O5+, which are situated near O VIII Lyman-α at 19 Å. Two of resulting wavelengths agree well with these reported earlier, but wavelength third line does not. In contrast, our new now fully those from resonant photo-absorption experiments PETRA III synchrotron facility.
As part of a larger project to complete comprehensive catalog astrophysically relevant emission lines in support new-generation X-ray observatories using the Lawrence Livermore electron beam ion traps EBIT-I and EBIT-II, we present observations argon extreme-ultraviolet region. Our database includes wavelength measurements with standard errors, relative intensities, line assignments for Ar IX-Ar XVI between 20 50 Å. The experimental data are complemented full set calculations Hebrew...
A R=44.3 m grazing-incidence grating spectrometer has been implemented on the Livermore electron beam ion traps for high-resolution measurements in soft x-ray and extreme ultraviolet region spanning from below 10 up to 50 Å. The instrument uses a with variable line spacing (about 2400 l/mm flat field of view. Spectra are recorded back-illuminated charge-coupled device detector. new greatly improves upon resolution achieved existing spectrometers complements crystal at shorter wavelengths...
We present high-resolution crystal spectroscopy measurements of the $n=3\ensuremath{\rightarrow}n=2$ $L$-shell x-ray transitions neonlike W${}^{64+}$, which include seven electric-dipole--allowed transitions, two electric quadrupole and one magnetic transition. The resulting wavelength data are compared to recent calculational results, allowing us clearly distinguish between different theoretical approaches need take into account not only substantial electron correlations effects but also...
Spectroscopy in the extreme ultraviolet region is important to magnetic fusion research as well astrophysics. We report on XEUS (X-ray and Extreme Ultraviolet Spectrometer) LoWEUS (Long-Wavelength Spectrometer), which operate 5–400 Å NSTX (National Spherical Tokamak Experiment) tokamak. The instruments are being used survey impurities, both for intrinsic elements present plasma metal impurities resulting from damage various components. In addition, we have investigate density-dependent...
We report on emission spectra of iron in the extreme ultraviolet recorded at an electron density ~5 × 1011 cm-3 Lawrence Livermore beam ion trap EBIT-II. present a summary observed lines, including wavelengths and intensities. also illustrate our technique for isolating pure charge states desired Fe VII-Fe X. Our measurements add large number newly identified lines to existing line lists extreme-ultraviolet region, 60-140 A. While many these are quite weak, they up significant flux that can...
We present a theoretical and experimental investigation of the $3d\ensuremath{\rightarrow}2p$ resonance to intercombination line ratio in low- mid-$Z$ neonlike ions astrophysical interest, i.e., $2{p}_{1/2}2{p}_{3/2}^{4}3{d}_{3/2}{}^{1}{P}_{1}^{o}\ensuremath{\rightarrow}2{p}^{6}{\phantom{\rule{0.16em}{0ex}}}^{1}{S}_{0}$ $2{p}_{1/2}^{2}2{p}_{3/2}^{3}3{d}_{5/2}\phantom{\rule{0.16em}{0ex}}{}^{3}{D}_{1}^{o}\ensuremath{\rightarrow}2{p}^{6}{\phantom{\rule{0.16em}{0ex}}}^{1}{S}_{0}$ transitions...
The line emission of Fe VII-Fe X ions in the extreme-ultraviolet region below 140 Å was measured controlled laboratory experiments under conditions representative stellar coronae. observations are compared with predictions from standard spectral models using CHIANTI and MEKAL atomic databases. We find that databases miss most flux this region. While some missing lines form isolated features, add up to a quasi continuum 60-120 This incompleteness can explain poor fit when applying...
The line ratios of the 2p-3d transitions in boron-like spectra Ar XIV and Fe XXII have been measured using electron beam ion traps at Lawrence Livermore National Laboratory. Radiative-collisional model calculations show these to be sensitive density ranges ne = 1010-1012 cm-3 1013-1015 cm-3, respectively. In our experiment, about 1011 was varied by a factor 5. Our data effect for doublet XIV, good agreement with theory is found. relative intensity shows predicted low-density limit. N VI...
As part of a larger project to complete comprehensive catalog astrophysically relevant emission lines in support new-generation X-ray observatories using the Lawrence Livermore electron beam ion traps EBIT-I and EBIT-II, we present observations sulfur soft extreme-ultraviolet regions. Our database includes wavelength measurements with standard errors, relative intensities, line assignments for 127 transitions S VII through XIV between 20 75 Å. The experimental data are complemented full set...
Laboratory measurements of the n = 3 to emission from M-shell iron ions are presented and compared synthetic spectra CHIANTI spectral model. The cover range 170–290 Å made at an electron density about 1011 cm−3. Emission Fe viii through xvi has been identified. Excellent agreement with predictions is found for most lines. Twenty weaker features noted in laboratory data that either absent or have recently added correspond lines not verified by experimental measurements. A few these may...
Using the SuperEBIT electron-beam ion trap and a flat-field spectrometer, we observed extreme ultraviolet spectra of highly charged ions Xe measured wavelengths prominent lines from Li-, Be-, B-, Na-, Mg-like ions. Our results for Li- Na-like are as precise best available elsewhere. The much more than data or extend those lower-$Z$ reveal significant shortcomings various theoretical predictions.
We present an analysis of the spectral emission Fe XIII near 200 Å. High-resolution spectra were recorded at two densities (~2 × 1011 and ~1013 cm−3) in laboratory compared to collisional radiative model calculations based on CHIANTI database, models using atomic data from distorted-wave R-matrix calculations. The lines this wavelength range are sensitive indicators plasma density below ~ cm–3. thus test astrophysical high-density limit. Significant differences between measurements found for...
Tungsten particles have been introduced into the National Spherical Torus Experiment (NSTX) in Princeton with purpose to investigate effects of tungsten injection on subsequent plasma discharges. An experimental setup for study particle transport is described where are tokamak using a modified dropper, otherwise used lithium-powder injection. initial test employing grazing-incidence extreme ultraviolet spectrometer demonstrates that tungsten-transport could serve infer from edge hot central...
We measured wavelengths and intensities of L-shell emission lines aluminum in the extreme ultraviolet wavelength band. identify 75 features Al IV through XI between 40 170 A. The strongest are due to 3 → 2 transitions; from 4 2, 5 6 transitions also included. Calculations made with Flexible Atomic Code using configuration-interaction method many-body perturbation theory presented compared experimental results.
We have analyzed 280 ks of co-added observations performed with Chandra's Low Energy Transmission Grating Spectrometer using theoretical spectra Fe viii through xvii. The model spectral data were produced by combining collisional excitation generated the Flexible Atomic Code and transition energies a relativistic code based on multi-reference Møller–Plesset perturbation theory. spectroscopic accuracy ix wavelengths was ascertained in comparison existing laboratory measurements. find several...
Abstract The coronal temperature of Capella and Procyon has been derived from the spectral emission Fe XVII observed in high resolution with Chandra ’ s High Energy Transmission Grating Spectrometer. measurement makes use well resolved dielectronic satellite features a spectator electron n = 4 shell. This method does not require priori knowledge ionization equilibrium or elemental abundances. We find is <?CDATA ${264}_{-51}^{+142}$?> eV for ${514}_{-25}^{+27}$?> Capella, i.e., 3.1 6.0 MK,...
A compact grazing-incidence spectrometer has been implemented on the National Spherical Torus Experiment for spectral measurements in 6–65Å region. The employed a 2400ℓ∕mm grating designed flat-field focusing and cryogenically cooled charge-coupled device camera readout. instrument was tested by recording K-shell lines of boron, carbon, nitrogen, oxygen, as well L-shell from argon, iron, nickel that fall into this band. observed linewidth about 0.1Å, which corresponds to resolving power 400...
We describe upgrades to a compact grazing-incidence spectrometer utilized on the National Spherical Torus Experiment for monitoring light and heavy impurities. A fast-readout charge couple device camera has been implemented that allows recording of spectra with up 25ms time integration. This capability is used study evolution K-shell emission hydrogenlike heliumlike boron, carbon, nitrogen, oxygen between 10 65Å. Different positioning pieces have employed extend possible spectral range as...
Multiple spectrometers originally designed for and used at the University of California Lawrence Livermore National Laboratory’s electron beam ion trap have found use various magnetically confined plasma facilities. Three examples will be described. First is a soft X-ray/EUV grating spectrometer (6–150 Å), which operating Spherical Torus Experiment. Second an EUV with wavelength coverage up to 400 Å, has just recently started Sustained Spheromak Physics The last high-resolution...
We report on upgrades to the flat-field grazing-incidence grating spectrometers X-ray and Extreme Ultraviolet Spectrometer (XEUS) Long-Wavelength (LoWEUS), at National Spherical Torus Experiment (NSTX) Princeton Plasma Physics Laboratory. XEUS employs a variable space with an average spacing of 2400 lines/mm covers 9–64 Å wavelength band, while LoWEUS has 1200 is positioned monitor 90–270 band. Both have been upgraded new cameras that achieve 12.5 ms time resolution. demonstrate resolution...
Electron beam ion traps are uniquely well suited for laboratory astrophysics because they can produce nearly any charge state of element in a collisionally excited plasma that is comparable density and temperature to many astronomical sources. The Lawrence Livermore EBIT facility has been optimized with suite dedicated instruments made significant advances this field. This paper reviews some the work performed at LLNL compiling comprehensive spectral catalogues, discovery magnetic field line...