Spectrograph Mode Research Articles

Synthesis of Fringing Magnetic Fields for Static Mass Analyzers of the Spectrographic Type

Static mass analyzers offer a unique potential opportunity to achieve 100% utilization of ions generated by a continuously operating ion source. However, to achieve this, it is necessary for the mass analyzer to operate in the spectrographic mode rather than in the spectrometric mode. It is known that the conventional Mattauch–Herzog scheme may operate in the spectrographic mode with double focusing (by both angle and energy) along the straight focal line but only in the first order. The usage of more complex optical solutions is prevented by the fringing fields of static magnets, which destroy the exact spectrographic mode of the instrument operation. It is shown in the presented study that by using the principle of the similarity of trajectories in Euler-homogeneous fields one can purposefully synthesize asymmetric fringing magnetic fields of a particular type, which keep the spectrographic mode and the straightness of the focus line for static mass analyzers. Such fringing fields and the corresponding fringing configurations of magnetic poles and screens can become a basis for static mass spectrographs of a new type with high optical characteristics.

Detecting Proxima b’s Atmosphere with JWST Targeting CO2 at 15 μm Using a High-pass Spectral Filtering Technique

Abstract Exoplanet Proxima b will be an important laboratory for the search for extraterrestrial life for the decades ahead. Here, we discuss the prospects of detecting carbon dioxide at 15 μm using a spectral filtering technique with the Medium Resolution Spectrograph (MRS) mode of the Mid-Infrared Instrument (MIRI) on the James Webb Space Telescope (JWST). At superior conjunction, the planet is expected to show a contrast of up to 100 ppm with respect to the star. At a spectral resolving power of R = 1790–2640, about 100 spectral CO2 features are visible within the 13.2–15.8 μm (3B) band, which can be combined to boost the planet atmospheric signal by a factor of 3–4, depending on the atmospheric temperature structure and CO2 abundance. If atmospheric conditions are favorable (assuming an Earth-like atmosphere), with this new application to the cross-correlation technique, carbon dioxide can be detected within a few days of JWST observations. However, this can only be achieved if both the instrumental spectral response and the stellar spectrum can be determined to a relative precision of ≤1 × 10−4 between adjacent spectral channels. Absolute flux calibration is not required, and the method is insensitive to the strong broadband variability of the host star. Precise calibration of the spectral features of the host star may only be attainable by obtaining deep observations of the system during inferior conjunction that serve as a reference. The high-pass filter spectroscopic technique with the MIRI MRS can be tested on warm Jupiters, Neptunes, and super-Earths with significantly higher planet/star contrast ratios than the Proxima system.

Static mass spectrographs of a new type using Euler’s homogeneous electric and magnetic fields. II: Conditions of high-order double focusing for two-cascade schemes

Static mass spectrometers are masked by more modern and more sophisticated mass spectrometric instruments, but their potential nowhere is almost exhausted. One of the principle advantages of static mass spectrometers is that they are the only type of mass spectrometric instruments capable of operating in a spectrographic mode by measuring the whole range of masses per a single run. However, systems with good spectrographic properties significantly differ from the optical point of view from systems with good spectrometric properties, and the development of such devices leads to completely new optical problems and, accordingly, to novel methods of their solution. In this paper, we consider possibilities related to the application of electrostatic and magnetostatic fields, homogeneous in Euler’s terms, to the development of two-cascade mass spectrographs with double focusing.

Static mass spectrometers of new type, using Euler’s homogeneous electric and magnetic fields. I. General principle and single-stage systems

Static mass spectrometers are inconspicuous against the background of more modern and more sophisticated mass spectrometers, but their potentiality is far from being exhausted. One of the principle advantages of static mass spectrometers is that they are the only type of mass spectrometers with a “duty cycle” of 100%. However, to implement this advantage, a static mass analyzer should work in a spectrographic mode, covering a considerable range of masses in one measurement. However, systems with good spectrographic properties significantly differ from systems with good spectrometric properties from the optical point of view, and the development of such devices leads to completely new optical problems and, correspondingly, to new approaches to their solution. One of useful tools to solve these problems are specific electrostatic and magnetostatic fields, homogeneous in the Euler terms. In this paper, prospects for the use of Euler’s homogeneous fields in creating static mass analyzers of a new generation are discussed.

On the impossibility of double focusing in combined electric and magnetic fields homogeneous in Euler’ terms

The use of Euler’s homogeneous electric and magnetic fields can be a good basis for designing static mass spectrometers capable of operating in a spectrographic mode and enabling recording of mass spectra with a wide mass range in one measurement. It is proved mathematically that, when combined Euler’s homogeneous electric and magnetic fields are used to design a single-cascade mass-spectrometer, the double focusing mode cannot be achieved practically along the entire focal line. It is demonstrated that the use of mass spectrographic schemes in which the electric stage and the magnetic stage are separated is an inevitable solution in the creating of a mass spectrograph with high analytical performance.

JOUVENCE OF FLUOR: UPGRADES OF A FIBER BEAM COMBINER AT THE CHARA ARRAY

The FLUOR (Fiber Linked Unit for Optical Recombination) interferometric beam combiner located at the CHARA Array on Mt. Wilson, California has recently undergone a program of major upgrades known as Jouvence of FLUOR (JouFLU). These upgrades seek to improve the precision, use, and observing efficiency of FLUOR as well as introduce new modes of operation. A Fourier Transform Spectrograph (FTS) mode and a spectral dispersion mode have been added to improve calibration and data collection. New mechanized stages and new cameras have been added to FLUOR for alignment and pupil plane imaging. Entirely new control/command software has been written for FLUOR which brings it into compliance with CHARA software standards. This allows for continued software upgrades and full remote operation capability. The new JouFLU instrument is now operating on sky and is expected to achieve accurate interferometric visibility amplitude measurements with 0.1 to 0.3% precision.

1.6 m 신태양망원경용 고속영상태양분광기 개발

KASI and Seoul National University developed the Fast Imaging Solar Spectrograph (FISS) as one of major scientific instruments for the 1.6 m New Solar Telescope (NST) and installed it in the Coude room of the NST at Big Bear Solar Observatory (BBSO) in May, 2010. The major objective of the FISS is to study the fine-scale structures and dynamics of plasma in the photosphere and chromosphere. To achieve it, the FISS is required to take data with a spectral resolution higher than <TEX>$10^5$</TEX> at the spectrograph mode and a temporal resolution less than 10 seconds at the imaging mode. The FISS is a spectrograph using Echelle grating and has characteristics that can observe dual bands (H<TEX>${\alpha}$</TEX> and CaII 8542) simultaneously and perform fast imaging using fast raster scan and two fast CCD cameras. In this paper, we introduce briefly the whole process of FISS development from the requirement analysis to the first observations.

Ionized Gas and Sources of its Ionization in the Irr Galaxy IC 10

IC 10 is the nearest starburst irregular galaxy remarkable for its anomalously high number of WR stars. We report the results of an analysis of the emission spectra of HII-regions ionized by star clusters and WR stars based on observations made with the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences using MPFS field spectrograph and SCORPIO focal reducer operating in the slit spectrograph mode. We determine the masses and ages of ionizing star clusters in the violent star-forming region of the galaxy in terms of the new evolutionary models of emission-line spectra of HII-regions developed by Martin-Manjon et al. (2010). We estimate the amount of stars needed to ionize the gas in the brightest HII-region HL 111 and report new determinations of oxygen abundance in HII regions.

Integral Field Spectroscopy of the Quadruply Lensed Quasar 1RXS J1131−1231: New Light on Lens Substructures

We have observed the quadruply lensed quasar 1RXS J1131-1231 with the integral field spectrograph mode of the Kyoto Tridimensional Spectrograph II mounted on the Subaru telescope. Its field of view has covered simultaneously the three brighter lensed images A, B, and C, which are known to exhibit anomalous flux ratios in their continuum emission. We have found that the [OIII] line flux ratios among these lensed images are consistent with those predicted by smooth-lens models. The absence of both microlensing and millilensing effects on this [OIII] narrow line region sets important limits on the mass of any substructures along the line of sight, which is expressed as M_E < 10^5 M_solar for the mass inside an Einstein radius. In contrast, the H_beta line emission, which originates from the broad line region, shows an anomaly in the flux ratio between images B and C, i.e., a factor two smaller C/B ratio than predicted by smooth-lens models. The ratio of A/B in the H_beta line is well reproduced. We show that the anomalous C/B ratio for the H_beta line is caused most likely by micro/milli-lensing of image C. This is because other effects, such as the differential dust extinction and/or arrival time difference between images B and C, or the simultaneous lensing of another pair of images A and B, are all unlikely. In addition, we have found that the broad H_beta line of image A shows a slight asymmetry in its profile compared with those in the other images, which suggests the presence of a small microlensing effect on this line emitting region of image A.

THE KECK LOW-RESOLUTION IMAGING SPECTROMETER

ABSTRACT The Low Resolution Imaging Spectrometer (LRIS) for the Cassegrain focus of the Keck 10-meter telescope on Mauna Kea is described. It has an imaging mode so it can also be used for taking direct images. The field of view in both spectrographic and imaging modes is 6 by 7.8 arcmin. It can be used with both conventional slits and custom-punched slit masks. The optical quality of the spectrograph is good enough to take full advantage of the excellent imaging properties of the telescope itself. The detector is a cooled back-illuminated Tektronics Inc. 2048 CCD which gives a sampling rate of 4.685 pixels per arcsec. In the spectrographic mode the spectrograph has a maximum efficiency at the peak of the grating blaze of 32-34% for the two lowest resolution gratings and 28% for the 1200 g/mm grating. This efficiency includes the detector but not the telescope or the atmosphere.

The O.A.O. Spectronebulagraph and the Kyoto 3D Spectrograph

AbstractSpectronebulagraph, an automated observation system of tridimensional spectroscopy with a long slit spectrograph, is now in operation at the 188 cm telescope of the Okayama Astrophysical Observatory. This system is based on the local area net work of personal computers which control the telescope, the autoguider, the Cassegrain spectrograph and its CCD camera. Effects of variable atmospheric transmission during scans of target objects are removed by performing a set of two orthogonal scans and the data processing.A new spectrograph is now under development for the telescope. This instrument has multiple modes for tridimensional spectroscopy, i.e., the filter imagery mode, the imaging Fabry-Perot interferometer mode, a slit spectrograph mode for Spectronebulagraph, and the microlens array spectrograph (TIGER) mode. For the last mode, a dual preoptics to get simultaneously the sky background is introduced and achromatization of the microlenses is tried. This project is a part of development of a prototype instrument for the SUBARU telescope.

Monochromatic imaging instrumentation for applications in aeronomy of the earth and planets

Monochromatic imaging instrumentation has been developed that uses narrow-band [12-A full width at half maximum (FWHP)] interference filters or plane reflection gratings for 2-D imaging and imaging spectrograph applications. By changing the optics in front of the filter or grating, the field of view of the instruments can be varied from 180 deg (all sky) to 6 deg (narrow field). In the case of the 2-D monochromatic imager, the 12-mm-diam. filtered image is formed at ~f/1 on the input photocathode of an intensified CCD camera (380 x 488 pixels). Regardless of the field of view of the instrument, none of the rays passing through the filter exceeds 4.5 deg to the filter normal. In the spectrograph mode, a slit is placed on the field lens (at the focus of the objective lens) and the 4-in. interference filter is replaced with a reflection grating. The spectrum is imaged at f/1 onto the previously described detector with the spatial dimension of 380 pixels and the wavelength dimension of 488 pixels. The sensitivities of the systems are approximately 50 to 100 rayleigh seconds (Rs) (SNR~2). Examples of data taken with both of these instruments include detection and mapping of Jupiter's sodium magnetonebula and stable auroral red (SAR) arcs in the terrestrial ionosphere.

Feasibility study for an investigation of the neutrino rest mass through high resolution spectroscopy of the external bremsstrahlung from tritium decay

In a feasibility study we have investigated which upper limit might be measurable for the mass of the electron antineutrino through high-resolution spectroscopy of the external bremsstrahlung from β-decay of tritium. Various sources are considered to obtain high luminosity. A description is given of the fabrication of a 900 Ci NbT0.4 source. The design data of a curved crystal spectrometer are discussed, including aberration, in order to achieve high intensity in the spectrograph mode, aiming at a resolution of 20 eV. The expected bremsstrahlung spectrum has been calculated and compared with a spectrum measured with a Si(Li) spectrometer with the use of the Nb tritium source. This method yields an upper limit of ∼ 100 eV for mν.

High-resolution VUV spectroscopic facility at the Photon Factory

A high-resolution spectroscopic facility, consisting of a 6.65-m vertical dispersion off-plane Eagle spectrograph/monochromator and a unique predisperser system of zero-dispersion type, has been designed and constructed at the Photon Factory. A description is given of design principle, optical system, mechanical arrangement, vacuum system, control system, and performance in the spectrograph mode. The resolving power was estimated from the separation between two closely lying lines of Ar I at ∼79 nm in the seventh order to be &gt;2.5 × 105 —the highest resolving power ever demonstrated for this spectral region.

Versatile grazing incidence spectromonochromator for the xuv region

A new type of grazing incidence spectromonochromator, which can serve equally the need of synchrotron radiation research and plasma research, is presented. Making use of the Rowland circle mounting, it is based on the two-grating principle that proved to be very efficient in separating higher orders in a previous prototype. A new mechanical system, well adapted to the current possible uses, has been incorporated. The apparatus can work as a spectrograph or as a monochromator, with one or two gratings, with a mobile or a fixed exit slit. In the spectrograph mode it can be used either with a photographic chamber or with a photoelectric detector. The incidence angle on each grating can be varied continuously and the gratings can be easily changed and readjusted entirely with visible light. The adaptation of the apparatus to the synchrotron radiation emitted by the ACO storage ring is described and the first results of tests, concerning mainly its order-sorting capability, its resolution, and the absolute flux of photons available, are presented.

A normal incidence, vacuum ultraviolet, spectrograph/monochromator for time resolved plasma spectroscopy

A film holder/exit slit movement for a fixed-grating, vacuum ultraviolet spectrograph is described. Film clamped on a holder lying along the Rowland circle is used conventionally in the spectrograph mode. For use as a monochromator, the exit slit moves along the film holder and a phosphor/flexible lightguide combination couples the output radiation to a photomultiplier outside the vacuum system. The spectrum is covered from 25 nm to 200 nm using two gratings. The combination instrument is suitable for time resolved spectroscopy of a transient plasma with a complicated spectrum when reliable identification of spectral lines and accurate wavelength settings are necessary.