1
|
Paul MC, Scime EE. Continuous-wave planar laser induced fluorescence with a fast camera. Rev Sci Instrum 2021; 92:043532. [PMID: 34243371 DOI: 10.1063/5.0043499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 03/25/2021] [Indexed: 06/13/2023]
Abstract
We present planar, laser induced fluorescence (PLIF) measurements of the velocity-resolved distribution function of ions in a plasma using a modulated, narrow linewidth, continuous-wave laser. Plasma emission is acquired with a high frame rate camera, and the laser light is spread into a thin sheet so that an entire plane of the plasma is imaged at each interrogation wavelength. Fourier analysis is conducted on each pixel of the images to separate the modulated fluorescent emission from the background light. Argon ion temperatures and bulk flow maps are reported in a helicon plasma source, and standard single-point LIF measurements provide validation of the PLIF measurement.
Collapse
Affiliation(s)
- M C Paul
- Department of Physics and Astronomy and Center for KINETIC Plasma Physics, West Virginia University, Morgantown, West Virginia 26506, USA
| | - E E Scime
- Department of Physics and Astronomy and Center for KINETIC Plasma Physics, West Virginia University, Morgantown, West Virginia 26506, USA
| |
Collapse
|
2
|
Keesee AM, Buzulukova N, Mouikis C, Scime EE. Mesoscale Structures in Earth's Magnetotail Observed Using Energetic Neutral Atom Imaging. Geophys Res Lett 2021; 48:e2020GL091467. [PMID: 34054157 PMCID: PMC8151851 DOI: 10.1029/2020gl091467] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 12/17/2020] [Indexed: 05/31/2023]
Abstract
Mesoscale structures in Earth's magnetotail are a primary feature of particle transport to the inner magnetosphere during storms and substorms. We demonstrate that such structures can be observed in energetic neutral atom (ENA) data which can provide remote, global images of the magnetosphere. In particular, we present localized regions of increased ion temperatures that appear in equatorial ion temperature maps calculated from Two Wide-angle Imaging Neutral-atom Spectrometers (TWINS) ENA data. These regions are associated with a dipolarization front with bursty ion flows measured by Magnetospheric MultiScale (MMS) and are concurrent with substorm features observed in field aligned currents (FAC) from Active Magnetosphere and Planetary Electrodynamics Response Experiment measurements. We conduct a magnetohydrodynamics simulation of the same event and show simulated ion temperatures, ion flows, and FACs that agree with the measurements. However, the observed plasma heating is less intense in the simulated results than in the TWINS and MMS data, indicating that some heating processes may be missing from the model.
Collapse
Affiliation(s)
- A. M. Keesee
- Department of Physics and Astronomy, University of New Hampshire, Durham, NH, USA
- Space Science Center, University of New Hampshire, Durham, NH, USA
| | - N. Buzulukova
- Goddard Space Flight Center, Greenbelt, MD, USA
- University of Maryland, College Park, MD, USA
| | - C. Mouikis
- Space Science Center, University of New Hampshire, Durham, NH, USA
| | - E. E. Scime
- Department of Physics and Astronomy, West Virginia University, Morgantown, WV, USA
| |
Collapse
|
3
|
Paul MC, Steinberger TE, Lister EAM, Arnold NI, Artis D, Thakur SC, Hall T, LeBlanc S, Scime EE, Thomas E, Tynan GR. Compact, portable, laser induced fluorescence diagnostic for laboratory plasma sources. Rev Sci Instrum 2021; 92:013502. [PMID: 33514234 DOI: 10.1063/5.0031217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 12/14/2020] [Indexed: 06/12/2023]
Abstract
As diagnostic groups are increasingly called upon to participate in experimental campaigns at remote facilities, there is a need to develop portable versions of plasma diagnostic systems. One such diagnostic is laser induced fluorescence (LIF). Here, we describe a portable LIF apparatus that eliminates the need for an optical table, beam splitters, and an optical chopper. All of the light exiting the laser system is coupled through optical fibers to the experiment and housekeeping diagnostics. The collected light is coupled through an optical fiber as well. A key feature is modulation of the tapered amplifier current instead of physical modulation of the laser output. Using this portable LIF system, measurements of ion temperature, ion flow, and relative metastable ion density are reported for two different remote experiments.
Collapse
Affiliation(s)
- M C Paul
- Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506, USA
| | - T E Steinberger
- Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506, USA
| | - E A M Lister
- Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506, USA
| | - N Ivan Arnold
- Physics, Auburn University, Auburn, Alabama 36849, USA
| | - D Artis
- Physics, Auburn University, Auburn, Alabama 36849, USA
| | - S Chakraborty Thakur
- Center for Energy Research, University of California San Diego, San Diego, California 92093, USA
| | - T Hall
- Physics, Auburn University, Auburn, Alabama 36849, USA
| | - S LeBlanc
- Physics, Auburn University, Auburn, Alabama 36849, USA
| | - E E Scime
- Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506, USA
| | - E Thomas
- Physics, Auburn University, Auburn, Alabama 36849, USA
| | - G R Tynan
- Center for Energy Research, University of California San Diego, San Diego, California 92093, USA
| |
Collapse
|
4
|
Keesee AM, Dugas M, Ellison S, Neal L, Scime EE, Thompson DS, Tersteeg J, Tucker CJ. Micro-spectrometer for fusion plasma boundary measurements. Rev Sci Instrum 2018; 89:10J116. [PMID: 30399907 DOI: 10.1063/1.5035365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2018] [Accepted: 06/07/2018] [Indexed: 06/08/2023]
Abstract
In situ probes are being developed to make direct, spatially resolved measurements of the ion energy spectra in the edge of tokamak plasmas while being easily replaced and requiring minimal resources. The ion spectrometers will consist of a combined collimator and energy analyzer fabricated from silicon and mated to a detector to yield a form factor of approximately 2.0 cm × 1.5 cm × 0.2 cm. Results of fabrication and testing of the combined collimator and energy analyzer element are presented.
Collapse
Affiliation(s)
- A M Keesee
- Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506, USA
| | - M Dugas
- Advanced Research Corporation, White Bear Lake, Minnesota 55110, USA
| | - S Ellison
- Advanced Research Corporation, White Bear Lake, Minnesota 55110, USA
| | - L Neal
- Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506, USA
| | - E E Scime
- Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506, USA
| | - D S Thompson
- Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506, USA
| | - J Tersteeg
- Advanced Research Corporation, White Bear Lake, Minnesota 55110, USA
| | - C J Tucker
- NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
| |
Collapse
|
5
|
Thompson DS, Steinberger TE, Keesee AM, Scime EE. Laser induced fluorescence of Ar-I metastables in the presence of a magnetic field. ACTA ACUST UNITED AC 2018. [DOI: 10.1088/1361-6595/aac963] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|
6
|
Chakraborty Thakur S, Adriany K, Gosselin JJ, McKee J, Scime EE, Sears SH, Tynan GR. Laser induced fluorescence measurements of axial velocity, velocity shear, and parallel ion temperature profiles during the route to plasma turbulence in a linear magnetized plasma device. Rev Sci Instrum 2016; 87:11E513. [PMID: 27910698 DOI: 10.1063/1.4959275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We report experimental measurements of the axial plasma flow and the parallel ion temperature in a magnetized linear plasma device. We used laser induced fluorescence to measure Doppler resolved ion velocity distribution functions in argon plasma to obtain spatially resolved axial velocities and parallel ion temperatures. We also show changes in the parallel velocity profiles during the transition from resistive drift wave dominated plasma to a state of weak turbulence driven by multiple plasma instabilities.
Collapse
Affiliation(s)
- S Chakraborty Thakur
- Center for Energy Research, University of California at San Diego, San Diego, California 92093-0417, USA
| | - K Adriany
- Center for Energy Research, University of California at San Diego, San Diego, California 92093-0417, USA
| | - J J Gosselin
- Center for Energy Research, University of California at San Diego, San Diego, California 92093-0417, USA
| | - J McKee
- Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506, USA
| | - E E Scime
- Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506, USA
| | - S H Sears
- Department of Physics, University of Wisconsin at Madison, Madison, Wisconsin 53706, USA
| | - G R Tynan
- Center for Energy Research, University of California at San Diego, San Diego, California 92093-0417, USA
| |
Collapse
|
7
|
Scime EE, Keesee AM, Dugas M, Ellison S, Tersteeg J, Wagner G, Barrie A, Rager A, Elliott D. A micro-scale plasma spectrometer for space and plasma edge applications (invited). Rev Sci Instrum 2016; 87:11D302. [PMID: 27910531 DOI: 10.1063/1.4960145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
A plasma spectrometer design based on advances in lithography and microchip stacking technologies is described. A series of curved plate energy analyzers, with an integrated collimator, is etched into a silicon wafer. Tests of spectrometer elements, the energy analyzer and collimator, were performed with a 5 keV electron beam. The measured collimator transmission and energy selectivity were in good agreement with design targets. A single wafer element could be used as a plasma processing or fusion first wall diagnostic.
Collapse
Affiliation(s)
- E E Scime
- Department of Physics, West Virginia University, Morgantown, West Virginia 26506-6315, USA
| | - A M Keesee
- Department of Physics, West Virginia University, Morgantown, West Virginia 26506-6315, USA
| | - M Dugas
- Advanced Research Corporation, White Bear Lake, Minnesota 55110, USA
| | - S Ellison
- Advanced Research Corporation, White Bear Lake, Minnesota 55110, USA
| | - J Tersteeg
- Advanced Research Corporation, White Bear Lake, Minnesota 55110, USA
| | - G Wagner
- Advanced Research Corporation, White Bear Lake, Minnesota 55110, USA
| | - A Barrie
- NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
| | - A Rager
- NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
| | - D Elliott
- Department of Physics, West Virginia University, Morgantown, West Virginia 26506-6315, USA
| |
Collapse
|
8
|
Magee RM, Galante ME, McCarren D, Scime EE, Boivin RL, Brooks NH, Groebner RJ, Hill DN, Porter GD. A two photon absorption laser induced fluorescence diagnostic for fusion plasmas. Rev Sci Instrum 2012; 83:10D701. [PMID: 23126875 DOI: 10.1063/1.4728092] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The quality of plasma produced in a magnetic confinement fusion device is influenced to a large extent by the neutral gas surrounding the plasma. The plasma is fueled by the ionization of neutrals, and charge exchange interactions between edge neutrals and plasma ions are a sink of energy and momentum. Here we describe a diagnostic capable of measuring the spatial distribution of neutral gas in a magnetically confined fusion plasma. A high intensity (5 MW/cm(2)), narrow bandwidth (0.1 cm(-1)) laser is injected into a hydrogen plasma to excite the Lyman β transition via the simultaneous absorption of two 205 nm photons. The absorption rate, determined by measurement of subsequent Balmer α emission, is proportional to the number of particles with a given velocity. Calibration is performed in situ by filling the chamber to a known pressure of neutral krypton and exciting a transition close in wavelength to that used in hydrogen. We present details of the calibration procedure, including a technique for identifying saturation broadening, measurements of the neutral density profile in a hydrogen helicon plasma, and discuss the application of the diagnostic to plasmas in the DIII-D tokamak.
Collapse
Affiliation(s)
- R M Magee
- Physics Department, West Virginia University, Morgantown, 26506, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
9
|
Thakur SC, McCarren D, Lee T, Fedorczak N, Manz P, Scime EE, Tynan GR, Xu M, Yu J. Comparison of azimuthal ion velocity profiles using Mach probes, time delay estimation, and laser induced fluorescence in a linear plasma device. Rev Sci Instrum 2012; 83:10D708. [PMID: 23126882 DOI: 10.1063/1.4731005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We compare measurements of radially sheared azimuthal plasma flow based on time delay estimation (TDE) between two spatially separated Langmuir probes, Mach probes and laser induced fluorescence (LIF). TDE measurements cannot distinguish between ion fluid velocities and phase velocities. TDE and Mach probes are perturbative, so we compare the results against LIF, a non-perturbative, spatially resolved diagnostic technique that provides direct measurements of the ion velocity distribution functions. The bulk ion flow is determined from the Doppler shift of the Argon absorption line at 668.6139 nm. We compare results from all the three diagnostics, at various magnetic fields, which acts as a control knob for development of drift wave turbulence. We find that while Mach probes and LIF give similar profiles, TDE measurements typically overestimate the velocities and are also sensitive to the drift wave modes being investigated.
Collapse
Affiliation(s)
- S Chakraborty Thakur
- Center for Momentum Transport and Flow Organization, University of California at San Diego, 92093, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
10
|
Hansen AK, Galante M, McCarren D, Sears S, Scime EE. Simultaneous two-dimensional laser-induced-fluorescence measurements of argon ions. Rev Sci Instrum 2010; 81:10D701. [PMID: 21033894 DOI: 10.1063/1.3460630] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Recent laser upgrades on the Hot Helicon Experiment at West Virginia University have enabled multiplexed simultaneous measurements of the ion velocity distribution function at a single location, expanding our capabilities in laser-induced fluorescence diagnostics. The laser output is split into two beams, each modulated with an optical chopper and injected perpendicular and parallel to the magnetic field. Light from the crossing point of the beams is transported to a narrow-band photomultiplier tube filtered at the fluorescence wavelength and monitored by two lock-in amplifiers, each referenced to one of the two chopper frequencies.
Collapse
Affiliation(s)
- A K Hansen
- Department of Physics, West Virginia University, P.O. Box 6315, Morgantown, West Virginia 26506-6315, USA.
| | | | | | | | | |
Collapse
|
11
|
Przybysz WS, Ellis J, Thakur SC, Hansen A, Hardin RA, Sears S, Scime EE. A magneto-optic probe for magnetic fluctuation measurements. Rev Sci Instrum 2009; 80:103502. [PMID: 19895059 DOI: 10.1063/1.3238509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Results from a proof-of-principle experiment are presented that demonstrate it is possible to construct a completely optical, robust, and compact probe capable of spatially resolved measurements of magnetic field fluctuations smaller than 1 G over a frequency range of 1 Hz-8 MHz in a plasma. In contrast to conventional coil probes, the signal strength is independent of fluctuation frequency and the measurement technique is immune to electrostatic pickup. The probe consists of a high Verdet constant crystal, two polarizers, optical fibers, and a photodetector.
Collapse
Affiliation(s)
- W S Przybysz
- Department of Physics, West Virginia University, Morgantown, West Virginia 26506, USA
| | | | | | | | | | | | | |
Collapse
|
12
|
Thakur SC, Harvey Z, Biloiu IA, Hansen A, Hardin RA, Przybysz WS, Scime EE. Increased upstream ionization due to formation of a double layer. Phys Rev Lett 2009; 102:035004. [PMID: 19257364 DOI: 10.1103/physrevlett.102.035004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2008] [Indexed: 05/27/2023]
Abstract
We report observations that confirm a theoretical prediction that formation of a current-free double layer in a plasma expanding into a chamber of larger diameter is accompanied by an increase in ionization upstream of the double layer. The theoretical model argues that the increased ionization is needed to balance the difference in diffusive losses upstream and downstream of the expansion region. In our expanding helicon source experiments, we find that the upstream plasma density increases sharply at the same antenna frequency at which the double layer appears.
Collapse
Affiliation(s)
- S Chakraborty Thakur
- Department of Physics, West Virginia University, Morgantown, West Virginia 26506-6315, USA
| | | | | | | | | | | | | |
Collapse
|
13
|
Harvey Z, Thakur SC, Hansen A, Hardin R, Przybysz WS, Scime EE. Comparison of gridded energy analyzer and laser induced fluorescence measurements of a two-component ion distribution. Rev Sci Instrum 2008; 79:10F314. [PMID: 19044627 DOI: 10.1063/1.2953411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We present ion velocity distribution function (IVDF) measurements obtained with a five grid retarding field energy analyzer (RFEA) and IVDF measurements obtained with laser induced fluorescence (LIF) for an expanding helicon plasma. The ion population consists of a background population and an energetic ion beam. When the RFEA measurements are corrected for acceleration due to the electric potential difference across the plasma sheath, we find that the RFEA measurements indicate a smaller background to beam density ratio and a much larger parallel ion temperature than the LIF. The energy of the ion beam is the same in both measurements. These results suggest that ion heating occurs during the transit of the background ions through the sheath and that LIF cannot detect the fraction of the ion beam whose metastable population has been eliminated by collisions.
Collapse
Affiliation(s)
- Z Harvey
- Department of Physics, West Virginia University, Morgantown, West Virginia 26506-6315, USA
| | | | | | | | | | | |
Collapse
|
14
|
Maksimovic M, Zouganelis I, Chaufray JY, Issautier K, Scime EE, Littleton JE, Marsch E, McComas DJ, Salem C, Lin RP, Elliott H. Radial evolution of the electron distribution functions in the fast solar wind between 0.3 and 1.5 AU. ACTA ACUST UNITED AC 2005. [DOI: 10.1029/2005ja011119] [Citation(s) in RCA: 265] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- M. Maksimovic
- LESIA and CNRS; Observatoire de Paris-Meudon; Meudon France
| | - I. Zouganelis
- LESIA and CNRS; Observatoire de Paris-Meudon; Meudon France
| | - J.-Y. Chaufray
- LESIA and CNRS; Observatoire de Paris-Meudon; Meudon France
| | - K. Issautier
- LESIA and CNRS; Observatoire de Paris-Meudon; Meudon France
| | - E. E. Scime
- Department of Physics; West Virginia University; Morgantown West Virginia USA
| | - J. E. Littleton
- Department of Physics; West Virginia University; Morgantown West Virginia USA
| | - E. Marsch
- Max-Planck-Institut für Sonnensystemforschung; Katlenburg-Lindau Germany
| | - D. J. McComas
- Space Science and Engineering Division; Southwest Research Institute; San Antonio Texas USA
| | - C. Salem
- Space Sciences Laboratory; University of California; Berkeley California USA
| | - R. P. Lin
- Space Sciences Laboratory; University of California; Berkeley California USA
| | - H. Elliott
- Space Science and Engineering Division; Southwest Research Institute; San Antonio Texas USA
| |
Collapse
|
15
|
Kline JL, Scime EE, Boivin RF, Keesee AM, Sun X, Mikhailenko VS. RF absorption and ion heating in helicon sources. Phys Rev Lett 2002; 88:195002. [PMID: 12005639 DOI: 10.1103/physrevlett.88.195002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2001] [Indexed: 05/23/2023]
Abstract
Experimental data are presented that are consistent with the hypothesis that anomalous rf absorption in helicon sources is due to electron scattering arising from parametrically driven ion-acoustic waves downstream from the antenna. Also presented are ion temperature measurements demonstrating anisotropic heating (T( perpendicular)>T(parallel)) at the edge of the discharge. The most likely explanation is ion-Landau damping of electrostatic slow waves at a local lower-hybrid-frequency resonance.
Collapse
Affiliation(s)
- J L Kline
- Department of Physics, West Virginia University, Morgantown, West Virginia 26505, USA
| | | | | | | | | | | |
Collapse
|
16
|
Balkey MM, Scime EE, Schattenburg ML, van Beek J. Effects of Gap Width on Vacuum-Ultraviolet Transmission Through Submicrometer-Period, FreeStanding Transmission Gratings. Appl Opt 1998; 37:5087-5092. [PMID: 18285979 DOI: 10.1364/ao.37.005087] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The effects of gap width on the transmission coefficient of vacuum-ultraviolet light through submicrometer-period, freestanding transmission gratings are reported. Results from computations and an analytical waveguide model are shown to be consistent with experimental measurements. These results show that thin gratings with narrow gaps and thick gratings with wide gaps are equally effective at eliminating 121.6-nm radiation. The thin gratings with the narrow gaps have the advantage of better attenuation of shorter-wavelength radiation than the thick gratings with the larger gaps.
Collapse
|
17
|
Phillips JL, Bame SJ, Feldman WC, Gosling JT, Hammond CM, McComas DJ, Goldstein BE, Neugebauer M, Scime EE, Suess ST. Ulysses Solar Wind Plasma Observations at High Southerly Latitudes. Science 1995; 268:1030-3. [PMID: 17774231 DOI: 10.1126/science.268.5213.1030] [Citation(s) in RCA: 153] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Solar wind plasma observations made by the Ulysses spacecraft through -80.2 degrees solar latitude and continuing equatorward to -40.1 degrees are summarized. Recurrent high-speed streams and corotating interaction regions dominated at middle latitudes. The speed of the solar wind was typically 700 to 800 kilometers per second poleward of -35 degrees . Corotating reverse shocks persisted farther south than did forward shocks because of the tilt of the heliomagnetic streamer belt. Sporadic coronal mass ejections were seen as far south as -60.5 degrees . Proton temperature was higher and the electron strahl was broader at higher latitudes. The high-latitude wind contained compressional, pressure-balanced, and Alfvénic structures.
Collapse
|
18
|
Scime EE, Anderson EH, McComas DJ, Schattenburg ML. Extreme-ultraviolet polarization and filtering with gold transmission gratings. Appl Opt 1995; 34:648-654. [PMID: 20963164 DOI: 10.1364/ao.34.000648] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The polarization and transmission characteristics of freestanding gold transmission gratings, with 200-nm periods, for extreme-ultraviolet (EUV) radiation (1 < 200 nm) have been measured. We find that EUV transmission through the gratings is dominated by the waveguide characteristics of the gratings and that polarization efficiencies of 90% for wavelengths of 121.6 nm are achievable. Both the EUV polarization and transmission properties are in good agreement with a complete vector, numerical solution of Maxwell's equations. The fraction of open area to total area of the grating has been measured using a 10-keV proton beam and was found to be in good agreement with the microscopic slit and wire dimensions that were obtained by scanning electron microscopy. The use of these gratings for particle measurements in the presence of intense EUV radiation is briefly discussed.
Collapse
|
19
|
Moldwin MB, Phillips JL, Gosling JT, Scime EE, McComas DJ, Bame SJ, Balogh A, Forsyth RJ. Ulysses observation of a noncoronal mass ejection flux rope: Evidence of interplanetary magnetic reconnection. ACTA ACUST UNITED AC 1995. [DOI: 10.1029/95ja01123] [Citation(s) in RCA: 76] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|