This paper will describe a new Extreme Ultraviolet (EUV) test facility that is being developed at the Marshall Space
Flight Center (MSFC) to test EUV telescopes. Two flight programs, Hi-C, the high resolution coronal imager (a
sounding rocket program), and SUVI, the Solar Ultraviolet Imager (GOES-R), set the requirements for this new facility.
This paper will discuss those requirements, the EUV source characteristics, the wavelength resolution that is expected
and the vacuum chambers (Stray Light Facility, Xray Calibration Facility and the NSSTC EUV test chamber) where this
facility will be used.
This paper will describe the scientific goals of our sounding rocket program, the Solar Ultraviolet Magnetograph
Investigation (SUMI). This paper will present a brief description of the optics that were developed to meet SUMI's
scientific goals, discuss the spectral, spatial and polarization characteristics of SUMI's optics, describe SUMI's flight
which was launched 7/30/2010, and discuss what we have learned from that flight.
The solar chromosphere is an important boundary, through which all of the plasma, magnetic fields and energy in the
corona and solar wind are supplied. Since the Zeeman splitting is typically smaller than the Doppler line broadening in
the chromosphere and transition region, it is not effective to explore weak magnetic fields. However, this is not the case
for the Hanle effect, when we have an instrument with high polarization sensitivity (~ 0.1%). "Chromospheric Lyman-
Alpha SpectroPolarimeter (CLASP)" is the sounding rocket experiment to detect linear polarization produced by the
Hanle effect in Lyman-alpha line (121.567 nm) and to make the first direct measurement of magnetic fields in the upper
chromosphere and lower transition region. To achieve the high sensitivity of ~ 0.1% within a rocket flight (5 minutes) in
Lyman-alpha line, which is easily absorbed by materials, we design the optical system mainly with reflections. The
CLASP consists of a classical Cassegrain telescope, a polarimeter and a spectrometer. The polarimeter consists of a
rotating 1/2-wave plate and two reflecting polarization analyzers. One of the analyzer also works as a polarization beam
splitter to give us two orthogonal linear polarizations simultaneously. The CLASP is planned to be launched in 2014
summer.
This paper will describe the Marshall Space Flight Center's Solar Ultraviolet Magnetograph (SUMI) sounding rocket
program, with emphasis on the polarization characteristics of the VUV optics and their spectral, spatial and polarization
resolution. SUMI's first flight (7/30/2010) met all of its mission success criteria and this paper will describe the data
that was acquired with emphasis on the MgII linear polarization measurements.
KEYWORDS: Ultraviolet radiation, Spectral calibration, Solar processes, Aerospace engineering, Current controlled current source, Rockets, UV optics, Polarization, Magnetism, Sun
This paper describes the scientific goals of a sounding rocket program called the Solar Ultraviolet Magnetograph Investigation (SUMI), presents a brief description of the optics that were developed to meet those goals and discusses the spectral, spatial and polarization characteristics of SUMI's Toroidal Variable-Line-Space (TVLS) gratings, which are critical to SUMI's measurements of the magnetic field in the Sun's transition region.
Toroidal variable-line-space (VLS) gratings are very important in the design of an efficient VUV solar telescope that will measure the CIV (155nm) and MgII (280nm) emissions lines in the Sun's transition region. In 1983 Kita and Harada described spherical VLS gratings but the technology to commercially fabricate these devices is a recent development, especially for toroidal surfaces. This paper will describe why this technology is important in the development of the Solar Ultraviolet Magnetograph Investigation (SUMI) sounding rocket program (the good), the delays due to the conversion between the TVLS grating design and the optical fabrication (the bad), and finally the optical testing, alignment and tolerancing of the gratings (the ugly).
KEYWORDS: Magnetism, Polarization, Vacuum ultraviolet, Solar processes, Coronagraphy, Interferometers, Doppler effect, 3D modeling, Remote sensing, Current controlled current source
Marshall Space Flight Center's (MSFC) is developing a Vacuum Ultraviolet (VUV) Fabry-Pérot Interferometer that will be launched on a sounding rocket for high throughput, high-cadence, extended field of view CIV (155nm) measurements. These measurements will provide (i) Dopplergrams for studies of waves, oscillations, explosive events, and mass motions through the transition region, and, (ii), polarization measurements to study the magnetic field in the transition region. This paper will describe the scientific goals of the instrument, a brief description of the optics and the polarization characteristics of the VUV Fabry Pérot.
This paper will describe the objectives of the Marshall Space Flight Center (MSFC) Solar Ultraviolet Magnetograph
Investigation (SUMI) and the unique optical components that have been developed to meet those objectives. A sounding
rocket payload has been developed to test the feasibility of magnetic field measurements in the Sun's transition region.
The optics have been optimized for simultaneous measurements of two magnetic sensitive lines formed in the transition
region (CIV at 1550 Å and MgII at 2800 Å). This paper will concentrate on the polarization properties SUMI's toroidal
varied-line-space (TVLS) gratings and its system level testing as we prepare to launch in the Summer of 2008.
We present measurements of toroidal variable-line-space (TVLS) gratings for the Solar Ultraviolet Magnetograph
Investigation (SUMI), currently being developed at the National Space Science and Technology Center (NSSTC).
SUMI is a spectro-polarimeter designed to measure magnetic fields in the solar chromosphere by observing two UV
emission lines sensitive to magnetic fields, the CIV line at 155nm and the MgII line at 280nm. The instrument uses a
pair of TVLS gratings, to observe both linear polarizations simultaneously. Efficiency measurements were done on
bare aluminum gratings and aluminum/MgF2 coated gratings, at both linear polarizations.
KEYWORDS: Magnetism, Mirrors, Polarization, Space telescopes, Solar processes, Telescopes, Spatial resolution, Sun, Optical coatings, Signal to noise ratio
The Magnetic Transition Region Probe is a space telescope designed to measure the magnetic field at several heights and temperatures in the solar atmosphere, providing observations spanning the chromospheric region where the field is expected to become force free. The primary goal is to provide an early warning system (hours to days) for solar energetic particle events that pose a serious hazard to astronauts in deep space and to understand the source regions of these particles. The required magnetic field data consist of simultaneous circular and linear polarization measurements in several spectral lines over the wavelength range from 150 to 855 nm. Because the observations are photon limited an optical telescope with a large (>18m2) collecting area is required. To keep the heat dissipation problem manageable we have chosen to implement MTRAP with six separate Gregorian telescopes, each with ~ 3 m2 collecting area, that are brought to a common focus. The necessary large field of view (5 × 5 arcmin2) and high angular resolution (0.025 arcsec pixels) require large detector arrays and, because of the requirements on signal to noise (103), pixels with large full well depths to reduce the readout time and improve the temporal resolution. The optical and engineering considerations that have gone into the development of a concept that meets MTRAP's requirements are described.
This paper will describe the evolution of the Marshall Space Flight Center's (MSFC) electro-optical polarimeter with emphasis on the field-of-view characteristics of the KD*P modulator. Understanding those characteristics was essential to the success of the MSFC solar vector magnetograph. The paper will show how the field-of-view errors of KD*P look similar to the linear polarization patterns seen in simple sunspots and why the placement of the KD*P in a collimated beam was essential in separating the instrumental polarization from the solar signal. Finally, this paper will describe a modulator design which minimizes those field-of-view errors.
This paper will describe the Vacuum Ultraviolet (VUV) polarization testing of the Solar Ultraviolet Magnetograph (SUMI) optics. SUMI is being develop for a sounding rocket payload to prove the feasibility of making magnetic field measurements in the transition region. This paper will cover the polarization properties of the VUV calibration polarizers, the instrumental polarization of the VUV chamber, SUMI's toroidal varied-line-space gratings and the SUMI polarimeter.
This paper will describe the objectives of the Marshall Space Flight Center (MSFC) Solar Ultraviolet Magnetograph Investigation (SUMI) and the optical components that have been developed to meet those objectives. A sounding rocket payload is being developed to test the feasibility of magnetic field measurements in the Sun's transition region. The optics have been optimized for simultaneous measurements of two magnetic lines formed in the transition region (CIV at 1550Å and MgII at 2800Å). Finally, this paper will concentrate on the polarization properties of the SUMI polarimeter and toroidal variable-line-space gratings.
This paper will describe the objectives of the Marshall Space Flight Center (MSFC) Solar Ultraviolet Magnetograph Investigation (SUMI) and the optical components that have been developed to meet those objectives. In order to test the scientific feasibility of measuring magnetic fields in the UV, a sounding rocket payload is being developed. This paper will discuss: (1) the scientific measurements that will be made by the SUMI sounding rocket program, (2) how the optics have been optimized for simultaneous measurements of two magnetic lines CIV (1550Å) and MgII (2800Å), and (3) the optical, reflectance, transmission and polarization measurements that have been made on the SUMI telescope mirrors and polarimeter.
The polarizing optics that are being developed for the Solar UV Magnetograph Investigation (SUMI) are described. This polarimeter is being designed for a sounding rocket payload which will make simultaneous measurements of two magnetically sensitive lines CIV and MgII. With a limited observing program, the polarizing optics will be optimized for circular and linear polarization measurements in active regions. The Q polarization will represent exploratory measurements of the transverse field in strong sunspots. This paper will give a brief overview of the SUMI instrument and its scientific goals, will describe the polarimeter that will be used in the sounding rocket program, and will present some of the measurements that have been made on the SUMI polarization optics.
This paper will describe a new vector magnetograph that has been developed at Marshall Space Flight Center. This magnetograph was a test ed for space flight concepts. One of those concepts that is currently being tested is the increased sensitivity to linear polarization by replacing electro-optical and rotating waveplates with a rotating linear analyzer. Our paper will describe the motivation for developing this magnetograph, compare this instrument with traditional magnetograph designs.
This paper will describe the scientific objectives of the Marshall Space Flight Center (MSFC) Solar Ultraviolet Magnetograph Investigation (SUMI) and the optical components that have been developed to meet those objectives. In order to test the scientific feasibility of measuring magnetic fields in the UV, a sounding rocket payload is being developed. This paper will discuss: (1) the scientific measurements that will be made by the SUMI sounding rocket program, (2) how the optics have been optimized for simultaneous measurements of two magnetic lines CIV (1550 Angstroms) and MgII (2800 Angstroms), and (3) the optical, reflectance, transmission and polarization measurements that have been made on the SUMI telescope mirrors and polarimeter.
Traditional magnetographs measure the solar magnetic field at the visible 'surface' of the Sun, the photosphere. The Solar Ultraviolet Magnetograph Investigation (SUMI) is a hardware development study for an instrument to measure the solar magnetic field higher in the atmosphere, in the upper chromosphere and in the transition region at the base of the corona. The magnetic pressure at these levels is much stronger than the gas pressure (in contrast to the situation at the photosphere), so the field controls the structure and dynamics of the atmosphere. Rapid changes in the magnetic structure of the atmosphere become possible at this height, with the release of energy. Measurements of the vector magnetic field in this region will significantly improve our understanding of the physical processes heating the Sun's upper atmosphere and driving transient phenomena such as flares and coronal mass ejections. The instrument will incorporate new technologies to achieve the polarization efficiencies required to measure the magnetic splitting of lines in the VUV an UV (CIV at 1550 angstrom and MgII at 2800 angstrom). We describe the scientific goals, the optical components that are being developed for a sounding rocket program, and the SUMI baseline design.
Although zero-order quartz waveplates are widely used in instrumentation that needs good temperature and field-of-view characteristics, the residual errors associated with these devices can be very important in high-resolution polarimetry measurements. How the field-of-view characteristics are affected by retardation errors and the misalignment of optic axes in a double-crystal waveplate is discussed. The retardation measurements made on zero-order quartz and single-order "achromatic" waveplates and how the misalignment errors affect those measurements are discussed.
Although zero-order quartz waveplates are widely used in instrumentation that needs good temperature and field-of-view characteristics, the residual errors associated with these devices can be very important in high resolution polarimetry measurements. This paper will discuss how the field-of-view characteristics are affected by retardation errors and the misalignment of optic axes in a double crystal waveplate. The paper will then describe the retardation measurements that were made on zero-order quartz and single-order `achromatic' waveplates and how the misalignment errors affect those measurements.
A new vector magnetograph is being developed at NASA's Marshall Space Flight Center (MSFC) to measure polarization from active regions on the Sun. This paper will describe the polarization characteristics of the elements that make up the MSFC EXperimental Vector Magnetograph (EXVM) polarimeter. Based on those characteristics, the systematic errors associated with this polarimeter will be modeled and the polarization resolution that could be achieved in a space-based (or balloon-based) instrument will be discussed.
The instrumental crosstalk associated with the Marshall Space Flight Center Vector Magnetograph and the solar crosstalk created by the magnetic field are described and their impact on the reconstruction of the solar vector magnetic field is analyzed. It is pointed out that identifying and correcting the crosstalk is important in the development of realistic models describing the solar atmosphere. Solar crosstalk is spatially dependent on the structure of the magnetic field while instrumental crosstalk is dependent on the position of the analyzer.
A test program designed to study the DC modulation characteristics of longitudinal KD*P modulators and to determine what electrode structure might improve the performance of these devices is presented which was developed in the Marshall Space Flight Center. The physical constraints of these devices and the necessary electrical characteristics that the KD*P modulators must have to be used in the MSFC polarimeter are discussed.
Longitudinal KD*P modulators are used in ground-based solar magnetographs to eliminate seeing effects. Although the modulators can be used as variable retarders, the optical properties when zero voltage is applied influences the performance on instruments requiring very accurate polarization measurements. Measurements at the Marshall Space Flight Center are discussed in terms of the optical properties of KD*P modulators when zero voltage is applied. The measurements can be used to predict the modulation characteristics of the devices and to determine the polarization accuracy that can be expected from the vector magnetograph.
The Marshall Space Flight Center (MSFC) vector magnetograph records polarization images of absorption lines that are sensitive to magnetic fields. A method is presented for analyzing the Stokes spectral-line profiles of a photospheric Fe I absorption line (5250.2 A) which is influenced by the Zeeman effect. Using nonlinear least-square optimization, the observed Stokes profiles are compared with those generated from the theoretical solution of the polarized radiative transfer equations. The optimization process accounts for the spectral convolution of the source and the MSFC vector magnetograph. The resulting physical properties of the active region producing the polarized light are discussed.
This paper describes how FOV errors have affected the polarization measurements of the NASA Marshall vector magnetograph and how a polarimeter has been modified to minimize these errors. The design of a large-FOV (LFOV) KD*P modulator is discussed. The Poincare sphere is used to visualize the function of the different optical elements that make up the LFOV modulator.
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