C. M. Brown

EUV Emission Lines and Diagnostics Observed with Hinode/EIS

Quiet Sun and active region spectra from the Hinode/EIS instrument are presented, and the strongest lines from different temperature regions discussed. A list of emission lines recommended to be included in EIS observation studies is presented based on analysis of blending and diagnostic potential using the CHIANTI atomic database. In addition we identify the most useful density diagnostics from the ions covered by EIS.

The Bragg Crystal Spectrometer for SOLAR-A

The Bragg Crystal Spectrometer (BCS) is one of the instruments which makes up the scientific payload of the SOLAR-A mission. The spectrometer employs four bent germanium crystals, views the whole Sun and observes the resonance line complexes of H-like Fexxvi and He-like Fexxv, Caxix, and Sxv in four narrow wavelength ranges with a resolving power (λ/Δλ) of between 3000 and 6000. The spectrometer has approaching ten times better sensitivity than that of previous instruments thus permitting a time resolution of better than 1 s to be achieved. The principal aim is the measurement of the properties of the 10 to 50 million K plasma created in solar flares with special emphasis on the heating and dynamics of the plasma during the impulsive phase. This paper summarizes the scientific objectives of the BCS and describes the design, characteristics, and performance of the spectrometers.

Laboratory calibration of the Extreme-Ultraviolet Imaging Spectrometer for the Solar-B satellite

The laboratory end-to-end testing of the Extreme-Ultraviolet Imaging Spectrometer (EIS) for the Solar-B satellite is reported. A short overview of the EIS, which observes in two bands in the extreme-ultraviolet wavelength range, is given. The calibration apparatus is described, including details of the light sources used. The data reduction and analysis procedure are outlined. The wavelength calibration using a Penning source to illuminate the aperture fully is presented. We discuss the aperture determination using a radiometrically calibrated hollow-cathode-based source. We then give an account of the predicted and measured efficiencies from consideration of the efficiencies of individual optical elements in first order, an account of efficiencies out of band when radiation incident in one band is detected in the other, and efficiencies in multiple orders. The efficiencies measured in first order for in band and out of band are compared with the predictions and the sensitivity, and its uncertainties are derived. Application of the radiometric calibration is discussed.

Nonthermal velocities in solar active regions observed with the extreme-ultraviolet imaging spectrometer on Hinode

We discuss nonthermal velocities in an active region as revealed by the Extreme-Ultraviolet Imaging Spectrometer (EIS) on the Hinode spacecraft. The velocities are derived from spectral line profiles in the extreme-ultraviolet (EUV) from a strong line of Fe XII at 195.12 A by fitting each line profile to a Gaussian function. We compare maps of the full width at half-maximum values, the Fe XII spectral line intensity, the Fe XII Doppler shift, the electron temperature, and electron density. We find that the largest widths in the active region do not occur in the most intense regions, but seem to concentrate in less intense regions, some of which are directly adjacent to coronal loops, and some of which concentrate in regions which also exhibit relative Doppler outflows. The increased widths can also occur over extended parts of the active region.

Optics and mechanisms for the Extreme-Ultraviolet Imaging Spectrometer on the Solar-B satellite.

The Extreme-Ultraviolet Imaging Spectrometer (EIS) is the first of a new generation of normal-incidence, two-optical-element spectroscopic instruments developed for space solar extreme-ultraviolet astronomy. The instrument is currently mounted on the Solar-B satellite for a planned launch in late 2006. The instrument observes in two spectral bands, 170-210 A and 250-290 A. The spectrograph geometry and grating prescription were optimized to obtain excellent imaging while still maintaining readily achievable physical and fabrication tolerances. A refined technique using low ruling density surrogate gratings and optical metrology was developed to align the instrument with visible light. Slit rasters of the solar surface are obtained by mechanically tilting the mirror. A slit exchange mechanism allows selection among four slits at the telescope focal plane. Each slit is precisely located at the focal plane. The spectrograph imaging performance was optically characterized in the laboratory. The resolution was measured using the Mg iii and Ne iii lines in the range of 171-200 A. The He ii line at 256 A and Ne iii lines were used in the range of 251-284 A. The measurements demonstrate an equivalent resolution of ~2 arc sec? on the solar surface, in good agreement with the predicted performance. We describe the EIS optics, mechanisms, and measured performance.

4.5- and 8-keV emission and absorption x-ray imaging using spherically bent quartz 203 and 211 crystals (invited)

We have used spherically-bent quartz 203 and 211 crystals to image 4.5- and 8-keV sources in both emission and absorption geometries. These imaging systems are straightforward to align, provide high throughput, and can provide high spatial resolution over large fields of view. We discuss the imaging geometry and alignment strategies, and we present experimental results we have obtained from a 1-ns-duration, multikilojoule laser facility and from sub-ps-duration, ultrahigh-intensity laser facilities. Our successful applications suggest that high-quality, spherically-bent quartz crystals may be used to image at many different x-ray energies due to the numerous diffraction planes available from quartz. This range of usable x-ray energies increases the number of applications that might benefit from high-resolution, high-brightness, monochromatic x-ray imaging using bent crystals.

Repetitively pulsed-plasma soft x-ray source.

A 10-Hz Nd:YAG laser system with 0.6-J, 25-nsec pulses was used to produce plasmas which emitted strongly in the soft x-ray region. Spectral, temporal, and spatial characteristics of these plasma emissions are presented together with an application of the source to soft x-ray lithography.

3s–3p, 3p–3d, and 3d–4f transitions of sodiumlike ions

New measurements have been made for wavelengths of the 3s–3p, 3p–3d, and 3d–4f transitions of the sodiumlike ions Cu18+, Zn19+, Ga20+, Ge21+, As22+, Se23+, Br24+, Kr25+, Y28+, Zr29+, Nb30+, Mo31+, Ru33+, Rh34+, Pd35+, Ag36+, and Sn39+. The measurements were made by photographing laser-produced plasmas and tokamak plasmas with grazing-incidence spectrographs. The energies of the transitions were also calculated with Dirac–Fock computer codes. By fitting the differences between the observed and calculated wave numbers to simple formulas, least-squares-fitted wavelengths for all sodiumlike ions from Ar7+ to Xe43+ were determined. The estimated uncertainty of the fitted wavelengths is ±0.007 A, which makes them useful as reference values. The wavelengths range from 9 to 713 A.

Measurements of laser-imprinted perturbations and Rayleigh–Taylor growth with the Nike KrF laser

Nike is a 56 beam Krypton Fluoride (KrF) laser system using Induced Spatial Incoherence (ISI) beam smoothing with a measured focal nonuniformity 〈ΔI/I〉 of 1% rms in a single beam [S. Obenschain et al., Phys. Plasmas 3, 1996 (2098)]. When 37 of these beams are overlapped on the target, we estimate that the beam nonuniformity is reduced by 37, to (ΔI/I)≅0.15% (excluding short-wavelength beam-to-beam interference). The extraordinary uniformity of the laser drive, along with a newly developed x-ray framing diagnostic, has provided a unique facility for the accurate measurements of Rayleigh–Taylor amplified laser-imprinted mass perturbations under conditions relevant to direct-drive laser fusion. Data from targets with smooth surfaces as well as those with impressed sine wave perturbations agree with our two-dimensional (2-D) radiation hydrodynamics code that includes the time-dependent ISI beam modulations. A 2-D simulation of a target with a 100 A rms randomly rough surface finish driven by a completely unif...

Satellite measurements of hydroxyl in the mesosphere

The global distribution of hydroxyl (OH) in the middle atmosphere was recently measured by the Middle Atmosphere High Resolution Spectrograph Investigation (MAHRSI) on a satellite deployed and retrieved by the space shuttle. During 75 orbits, MAHRSI acquired 1800 daytime limb scans of the OH ultraviolet solar resonance fluorescence intensity. Each limb scan extends over the altitude region from 30 to 90 km and across 10° of latitude between 53°S and 63°N. OH number densities were retrieved using a Twomey regularization scheme constrained by the smoothness of the retrieved profile. Results provide a detailed description of the diurnal variation of mesospheric OH. Midmorning OH densities had a well defined peak of about 6 ×106 cm³ near 70 km, a broad minimum centered near 64 km, and rose to about 1 × 107 cm³ at 50 km. This profile is in substantial disagreement with photochemical model predictions [Summers et al., this issue]. The observations are compared with the two previous measurements.