391 research outputs found
From Predicting Solar Activity to Forecasting Space Weather: Practical Examples of Research-to-Operations and Operations-to-Research
The successful transition of research to operations (R2O) and operations to
research (O2R) requires, above all, interaction between the two communities. We
explore the role that close interaction and ongoing communication played in the
successful fielding of three separate developments: an observation platform, a
numerical model, and a visualization and specification tool. Additionally, we
will examine how these three pieces came together to revolutionize
interplanetary coronal mass ejection (ICME) arrival forecasts. A discussion of
the importance of education and training in ensuring a positive outcome from
R2O activity follows. We describe efforts by the meteorological community to
make research results more accessible to forecasters and the applicability of
these efforts to the transfer of space-weather research.We end with a
forecaster "wish list" for R2O transitions. Ongoing, two-way communication
between the research and operations communities is the thread connecting it
all.Comment: 18 pages, 3 figures, Solar Physics in pres
Solar energetic particles and their variability from the sun and beyond
With the onset of solar cycle 24 activity STEREO and near-Earth spacecraft are now measuring many multi-spacecraft solar particle events. We present examples of time-intensity distributions, energy spectra, fits to longitude distributions, a combined imaging/in-situ study, and MHD modeling of one event. Implications of these new results are discussed
Bioimaging using full field and contact EUV and SXR microscopes with nanometer spatial resolution
We present our recent results, related to nanoscale imaging in the extreme ultraviolet (EUV) and soft X-ray (SXR) spectral ranges and demonstrate three novel imaging systems recently developed for the purpose of obtaining high spatial resolution images of nanoscale objects with the EUV and SXR radiations. All the systems are based on laser-plasma EUV and SXR sources, employing a double stream gas puff target. The EUV and SXR full field microscopes-operating at 13.8 nm and 2.88 nm wavelengths, respectively-are currently capable of imaging nanostructures with a sub-50 nm spatial resolution with relatively short (seconds) exposure times. The third system is a SXR contact microscope, operating in the "water-window" spectral range (2.3-4.4 nm wavelength), to produce an imprint of the internal structure of the investigated object in a thin surface layer of SXR light sensitive poly(methyl methacrylate) photoresist. The development of such compact imaging systems is essential to the new research related to biological science, material science, and nanotechnology applications in the near future. Applications of all the microscopes for studies of biological samples including carcinoma cells, diatoms, and neurons are presented. Details about the sources, the microscopes, as well as the imaging results for various objects will be shown and discussed
Experimental inference of neutral and impurity transport in Alcator C-Mod using high-resolution x-ray and ultra-violet spectra
We present experimental inferences of cross-field impurity transport
coefficients for Alcator C-Mod plasmas using a novel forward model for the
entire Ca K-alpha spectrum, including satellite lines within the spectral
range, to compare to high-resolution X-ray Imaging Crystal Spectroscopy (XICS).
These measurements are complemented by Extreme Ultra-Violet (EUV) spectroscopy
that constrains transport closer to the edge. Using new atomic data sets for
both XICS and EUV analysis has enabled consideration of line ratios across both
spectral ranges and has increased the accuracy of inferred transport
coefficients. Inclusion of charge exchange between edge thermal neutrals and
impurities is shown to be extremely important in C-Mod pedestals. We obtain D
atomic neutral densities from experimental D Ly-alpha measurements at the
midplane and compare these to SOLPS-ITER simulations, finding good agreement.
Bayesian inferences of impurity transport coefficients are presented for L-,
EDA H-, and I-mode discharges, making use of the Aurora package for forward
modeling and combining our spectroscopic constraints. Experimentally inferred
diffusion profiles are found to match turbulent transport models at midradius
within uncertainties, using both quasilinear gyro-fluid TGLF SAT-1 and
nonlinear ion-scale gyrokinetic CGYRO simulations. Significant discrepancies in
convection are observed in some cases, suggesting difficulties in predictions
of flat or hollow impurity profiles.Comment: 23 pages of main body; 38 pages including appendices. 17 figures.
Submitted to Nuclear Fusio
Magnetic Reconnection Triggered by the Parker Instability in the Galaxy: Two-Dimensional Numerical Magnetohydrodynamic Simulations and Application to the Origin of X-Ray Gas in the Galactic Halo
We propose the Galactic flare model for the origin of the X-ray gas in the
Galactic halo. For this purpose, we examine the magnetic reconnection triggered
by Parker instability (magnetic buoyancy instability), by performing the
two-dimensional resistive numerical magnetohydrodynamic simulations. As a
result of numerical simulations, the system evolves as following phases: Parker
instability occurs in the Galactic disk. In the nonlinear phase of Parker
instability, the magnetic loop inflates from the Galactic disk into the
Galactic halo, and collides with the anti-parallel magnetic field, so that the
current sheets are created in the Galactic halo. The tearing instability
occurs, and creates the plasmoids (magnetic islands). Just after the plasmoid
ejection, further current-sheet thinning occurs in the sheet, and the anomalous
resistivity sets in. Petschek reconnection starts, and heats the gas quickly in
the Galactic halo. It also creates the slow and fast shock regions in the
Galactic halo. The magnetic field (G), for example, can heat the
gas ( cm) to temperature of K via the
reconnection in the Galactic halo. The gas is accelerated to Alfv\'en velocity
( km s). Such high velocity jets are the evidence of the
Galactic flare model we present in this paper, if the Doppler shift of the
bipolar jet is detected in the Galactic halo. Full size figures are available
at http://www.kwasan.kyoto-u.ac.jp/~tanuma/study/ApJ2002/ApJ2002.htmlComment: 13 pages, 12 figures, uses emulateapj.sty, accepted by Ap
- …