Interpretation of dust impact signals detected by Cassini at Saturn

2021 ◽  
Author(s):  
Libor Nouzak ◽  
Jiří Pavlů ◽  
Jakub Vaverka ◽  
Jana Šafránková ◽  
Zdeněk Němeček ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solitary Waves ◽  
Radial Distance ◽  
Wide Band ◽  
Plasma Parameters ◽  
Field Orientation ◽  
University Of Colorado ◽  
Spacecraft Potential ◽  
The University ◽  
Spike Waveforms

<p>The Cassini spacecraft spent more than 13 years in the dusty environment of Saturn. During this long period of investigations of the Saturn magnetosphere, the RPWS (Radio Plasma Wave Science) instrument recorded more than half a million spiky signatures. However, not all of them can be interpreted as dust impact signals because plasma structures like solitary waves can result in similar pulses.</p><p>We select the registered spike waveforms recorded by both dipole and monopole configurations of electric field antennas operated in 10 kHz or 80 kHz sampling rates at the distance of 0.2 Rs around the rings mid-plane. These waveforms were corrected using Cassini WBR (Wide Band Receiver) transfer function to obtain the correct shape of the signal. The signal polarity, amplitude, and timescales of different parts of the waveforms were quantitatively inspected according to the spacecraft potential, the density of the ambient plasma, the intensity of the Saturn’s magnetic field, and its orientation with respect to the spacecraft. The magnetic field orientation was also used for distinguishing between signals resulting from dust impacts and signals produced by solitary waves misinterpreted as dust impact signals.</p><p>The preliminary results of our study indicate similarities with previous laboratory studies of dust impact waveforms on the reduced model of Cassini bombarded with submicron-sized iron grains in external magnetic fields at the LASP facility of the University of Colorado. The polarity of the signals changes in accordance with a polarity of the spacecraft potential and pre-spike signals are also observed. The core of the paper is devoted to the relation between characteristics of dust impact signals and local plasma parameters and magnetic field intensity at the radial distance from 2 Rs to 60 Rs from Saturn surface.</p>

Dust impact signals detected by Cassini RPWS instrument at Saturn

2020 ◽  
Author(s):  
Libor Nouzak ◽  
Jiří Pavlů ◽  
Jakub Vaverka ◽  
Jana Šafránková ◽  
Zdeněk Němeček ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Plasma Plume ◽  
Potential Density ◽  
Field Orientation ◽  
University Of Colorado ◽  
Spacecraft Potential ◽  
Model Predictions ◽  
The Impact ◽  
The Magnetic Field ◽  
Science Instrument

<p>Cassini spacecraft spent at Saturn almost half of the Saturn year. During these 13 years in the Saturn magnetosphere, the RPWS (Radio Plasma Wave Science) instrument recorded more than half a million of waveforms with signatures that can be interpreted as dust impact signals. The RPWS antennas in both dipole and monopole configurations operated with 10 kHz or 80 kHz sampling rates during the mission.<br>We qualitatively and quantitatively analyze the registered waveforms taking into account the spacecraft potential, density of the ambient plasma, magnitude of the Saturn’s magnetic field and its orientation with respect to the spacecraft. The magnetic field orientation is also used for distinguishing between signals resulting from dust impacts and signals produced by solitary waves, which can exhibit similar shapes. The results of analysis are compared with a prediction of the dust impact model that was recently developed on a base of laboratory simulations. The simulations used the reduced model of Cassini that was bombarded with submicron-sized iron grains in the velocity range of 1–40 km/s at the 3 MV dust accelerator operated at the LASP facility of University of Colorado. The model predicts generation of impact signals due to different fractions of collected and escaped electron and ion charges from the impact plasma plume and different timescales of their expansion. The core of the paper is devoted to a discussion of differences between model predictions and observations.</p>

CrowdMag for personal interaction with Arctic magnetic variation

2020 ◽  
Author(s):  
Rick Saltus ◽  
Manoj Nair
Keyword(s):  
Magnetic Field ◽  
Citizen Science ◽  
Research Experience ◽  
Science Outreach ◽  
Aurora Borealis ◽  
University Of Colorado ◽  
Arctic Regions ◽  
Personal Interaction ◽  
The Earth ◽  
The University

<p>The Earth’s magnetic field is especially dynamic at high latitudes.  The most awesome manifestation of this is certainly the aurora borealis or northern lights – caused by the interaction of the solar wind with the Earth’s magnetic field.  Aside from the aurora you can’t see these magnetic variations.  But your phone can.  Virtually every modern smartphone is equipped with a 3-component magnetometer to enable the compass pointing capability for navigation.  CrowdMag is a popular NOAA/CIRES citizen science app that we developed to tap into your smartphone’s magnetometer.  It lets you interact with the Earth’s magnetic field.</p><p>The purpose of this presentation is to highlight the possibilities for using CrowdMag for science outreach and engagement, particularly in Arctic regions where day-to-day magnetic variations can exceed hundreds of nano-Teslas.  We will show example projects that were carried out by summer interns as part of the University of Colorado’s “Research Experience for Community College Students” (RECCS) program.  CrowdMag can be used to carry out various simple experiments for mapping and investigating the Earth’s magnetic field.  We seek input and collaboration with others interested in Citizen Science and outreach in Arctic regions.   </p>

scholarly journals Electrostatic Waves with Rapid Frequency Shifts in the Solar Wind Sunward of 1/3 AU

2021 ◽  
Author(s):  
Lily Kromyda ◽  
David M. Malaspina ◽  
Robert E. Ergun ◽  
Jasper Halekas ◽  
Michael L. Stevens ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Plasma Wave ◽  
Detection Algorithm ◽  
Space Physics ◽  
University Of California ◽  
Magnetic Fluctuations ◽  
Plasma Parameters ◽  
University Of Colorado ◽  
Background Magnetic Field

<p>During its first five orbits, the FIELDS plasma wave investigation on board Parker Solar Probe (PSP)  has observed a multitude of plasma waves, including electrostatic whistler and electron Bernstein waves (Malaspina et al. 2020), sunward propagating whistlers (Agapitov et al. 2020), ion-scale electromagnetic waves (Verniero et al. 2020, Bowen et al. 2020) and Alfven, slow and fast mode waves (Chaston et al. 2020).</p><p>The importance of these waves lies in their potential to redistribute the energy of the solar wind among different particles species (wave-particle interactions) or different types of waves (wave-wave interactions). The abundance of waves and instabilities observed with PSP points to their central role in the regulation of this energy exchange.</p><p>Here we present first observations of an intermittent, electrostatic and broadband plasma wave that is ubiquitous in the range of distances that PSP has probed so far. A unique feature of these waves (FDWs) is a frequency shift that occurs on millisecond timescales. In the frame of the spacecraft, FDWs usually appear between the electron cyclotron and electron plasma frequencies.</p><p>We develop a detection algorithm that identifies the FDWs in low cadence spectra. We analyze them using various statistical techniques. We establish their phenomenology and compare the magnetic fluctuations of the background magnetic field at times of FDWs and at times without FDWs. We establish their polarization with respect to the background magnetic field and search for correlations with various plasma parameters and features in the electron, proton and alpha particle distribution moments. We also investigate possible plasma wave modes that could be responsible for the growth of FDWs and the instability mechanisms that could be generating them.</p><p> </p><p>Lily Kromyda*<sup>(1)</sup>, David M. Malaspina <sup>(1,2)</sup>, Robert E. Ergun<sup>(1,2) </sup>, Jasper Halekas<sup>(3)</sup>, Michael L. Stevens<sup>(4) </sup>, Jennifer Verniero<sup>(5)</sup>, Alexandros Chasapis<sup>(2) </sup>, Daniel Vech<sup>(2) </sup>, Stuart D. Bale<sup>(5,6) </sup>, John W. Bonnell<sup>(5) </sup>, Thierry Dudok de Wit<sup>(7) </sup>, Keith Goetz<sup>(8) </sup>, Katherine Goodrich<sup>(5) </sup>, Peter R. Harvey<sup>(5) </sup>, Robert J. MacDowall<sup>(9) </sup>, Marc Pulupa<sup>(5) </sup>, Anthony W. Case<sup>(4) </sup>, Justin C. Kasper<sup>(10) </sup>, Kelly E. Korreck<sup>(4) </sup>, Davin Larson<sup>(5) </sup>, Roberto Livi<sup>(5) </sup>, Phyllis Whittlesey<sup>(5)</sup></p><p>(1) Astrophysical and Planetary Sciences Department, University of Colorado, Boulder, CO, USA</p><p>(2) Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO, USA</p><p>(3)  University of Iowa, Iowa City, IA, USA</p><p>(4) Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, USA</p><p>(5)  Space Sciences Laboratory, University of California, Berkeley, CA, USA</p><p>(6) Physics Department, University of California, Berkeley, CA, USA</p><p>(7)  LPC2E, CNRS, and University of Orleans, Orleans, France</p><p>(8)  School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, USA</p><p>(9)  NASA Goddard Space Flight Center, Greenbelt, MD, USA</p><p>(10) University of Michigan, Ann Arbor, MI, USA</p>

The 1-MeV Electron Microscope Installation at the University of Colorado

1973 ◽  
Vol 31 ◽  
pp. 8-9 ◽  
Author(s):  
Mircea Fotino
Keyword(s):  
Electron Microscopy ◽  
Developmental Biology ◽  
Transmission Electron Microscopy ◽  
Electron Microscope ◽  
National Institutes Of Health ◽  
Experimental Program ◽  
University Of Colorado ◽  
Transmission Electron ◽  
The University ◽  
Research Resources

A new 1-MeV transmission electron microscope (Model JEM-1000) was installed at the Department of Molecular, Cellular and Developmental Biology of the University of Colorado in Boulder during the summer and fall of 1972 under the sponsorship of the Division of Research Resources of the National Institutes of Health. The installation was completed in October, 1972. It is installed primarily for the study of biological materials without many of the limitations hitherto unavoidable in standard transmission electron microscopy. Only the technical characteristics of the installation are briefly reviewed here. A more detailed discussion of the experimental program under way is being published elsewhere.

Discourse Mapping

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Joanna BOEHNERT
Keyword(s):  
Environmental Politics ◽  
Technology Policy ◽  
Policy Research ◽  
Mapping Method ◽  
Science And Technology Policy ◽  
Design Practice ◽  
Analysis Method ◽  
Environmental Sciences ◽  
University Of Colorado ◽  
The University

This workshop will create a space for discussion on environmental politics and its impact on design for sustainable transitions. It will help participants identify different sustainability discourses; create a space for reflection on how these discourses influence design practice; and consider the environmental and social implications of different discourses. The workshop will do this work by encouraging knowledge sharing, reflection and interpretative mapping in a participatory space where individuals will create their own discourse maps. This work is informed by my research “Mapping Climate Communication” conducted at the Centre for Science and Technology Policy Research (CSTPR) in the Cooperative Institute for Environmental Sciences (CIRES), the University of Colorado, Boulder. With this research project I developed a discourse mapping method based on the discourse analysis method of political scientists and sustainability scholars. Using my own work as an example, I will facilitate a process that will enable participants to create new discourse maps reflecting their own ideas and agendas.

scholarly journals Assessing Genetic Variants in Matched Biocompartments From Patients With Serous Ovarian Cancer

2021 ◽  
Vol 20 ◽  
pp. 153303382110279
Author(s):  
Brooke E. Sanders ◽  
Lisa Ku ◽  
Paul Walker ◽  
Benjamin G. Bitler
Keyword(s):  
Ovarian Cancer ◽  
Genetic Variants ◽  
Mutant Allele ◽  
Serous Ovarian Cancer ◽  
Brca Testing ◽  
Panel Testing ◽  
University Of Colorado ◽  
Gene Panel Testing ◽  
The University ◽  
Tumor Profiling

The clinical use of molecular tumor profiling (MTP) is expanding and there is an increasing use of MTP data to manage patient care. At the University of Colorado, 18 patients were diagnosed with primary serous ovarian cancer between 9/2015 and 6/2019 and consented for banking and analysis of tumor, ascites and plasma. All 18 patients had tumor and plasma samples that were sent for MTP, and 13 of 18 patients additionally had ascites collected and sent for MTP. 50-gene panel testing and BRCA testing were performed on primary tumor. BRCA genetic variants were more likely to be identified in plasma as compared to ascites or tumor, though not statistically significant ( P = 0.17). Co-occurring genetic variants between plasma and ascites were less common in comparison to co-occurring variants between tumor and plasma or tumor and ascites, though not statistically significant ( P = 0.68). Variants in KDR (VEGFR2) and TP53 were most likely to be conserved across all 3 biocompartments. Mutant allele frequencies (MAF) of individual genetic variants varied across biocompartments, though tended to be highest in the tumor, followed by ascites.

Long-pulse plasma source for SMOLA helical mirror

2021 ◽  
Vol 87 (2) ◽  
Author(s):  
Ivan A. Ivanov ◽  
V. O. Ustyuzhanin ◽  
A. V. Sudnikov ◽  
A. Inzhevatkina
Keyword(s):  
Magnetic Field ◽  
Gas Flow ◽  
Supply Voltage ◽  
Hydrogen Plasma ◽  
Plasma Source ◽  
Lanthanum Hexaboride ◽  
Plasma Stream ◽  
Plasma Parameters ◽  
Plasma Properties ◽  
Plasma Gun

A plasma gun for forming a plasma stream in the open magnetic mirror trap with additional helicoidal field SMOLA is described. The plasma gun is an axisymmetric system with a planar circular hot cathode based on lanthanum hexaboride and a hollow copper anode. The two planar coils are located around the plasma source and create a magnetic field of up to 200 mT. The magnetic field forms the magnetron configuration of the discharge and provides a radial electric insulation. The source typically operates with a discharge current of up to 350 A in hydrogen. Plasma parameters in the SMOLA device are Ti ~ 5 eV, Te ~ 5–40 eV and ni ~ (0.1–1)  × 1019 m−3. Helium plasma can also be created. The plasma properties depend on the whole group of initial technical parameters: the cathode temperature, the feeding gas flow, the anode-cathode supply voltage and the magnitude of the cathode magnetic insulation.

Sign in / Sign up

Export Citation Format

Share Document