Difference between revisions of "FG: The Impact of the Cold Plasma in Magnetospheric Physics"

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== <B>Description </B>==
 
== <B>Description </B>==
The cold-particle populations that exist in the magnetosphere (cf. Table 1) include (1) plasmaspheric ions (including the plume), (2) plasmaspheric electrons (including the plume), (3) cloak ions, (4) oxygen torus, (5) cloak electrons, (6) outflowing cold electrons, (7) outflowing cold ions and (8) charge-exchange-byproduct cold protons (CHEX protons). Outflowing (from the ionosphere) cold electrons are anticipated for the maintenance of charge neutrality in the magnetosphere: two places where they should occur are (a) in the post-midnight to dawn region where the electron plasma sheet precipitates away to make diffuse aurora and (b) at the inner edge of the electron plasma sheet where (owing to gradient-curvature drift effects) the ion plasma sheet flows radially Earthward while the electron plasma sheet flows eastward. There are also plasmaspheric-refilling cold-ion and cold-electron outflows into open-drift-trajectory flux tubes on the dayside.
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The cold (<1 keV) particle populations that exist in the magnetosphere (cf. Table 1) include (1) plasmaspheric ions (including the plume), (2) plasmaspheric electrons (including the plume), (3) cloak ions, (4) oxygen torus, (5) cloak electrons, (6) outflowing cold electrons, (7) outflowing cold ions and (8) charge-exchange-byproduct cold protons (CHEX protons). Outflowing (from the ionosphere) cold electrons are anticipated for the maintenance of charge neutrality in the magnetosphere: two places where they should occur are (a) in the post-midnight to dawn region where the electron plasma sheet precipitates away to make diffuse aurora and (b) at the inner edge of the electron plasma sheet where (owing to gradient-curvature drift effects) the ion plasma sheet flows radially Earthward while the electron plasma sheet flows eastward. There are also plasmaspheric-refilling cold-ion and cold-electron outflows into open-drift-trajectory flux tubes on the dayside.
  
 
While the hot (ring current/plasma sheet) and energetic (radiation belts) populations have received a lot of attention because of their potential harm to space infrastructure, the cold-plasma populations are the least studied so that in some cases they have been referred to as the ‘hidden populations’. This is because (1) spacecraft are almost always charged to values that make measuring the cold-ion properties very difficult and (2) spacecraft surfaces exposed to sunlight and bombarded by energetic particles emit copious amounts of low-energy secondary and photoelectrons that blind the measurement of magnetospheric cold electrons.
 
While the hot (ring current/plasma sheet) and energetic (radiation belts) populations have received a lot of attention because of their potential harm to space infrastructure, the cold-plasma populations are the least studied so that in some cases they have been referred to as the ‘hidden populations’. This is because (1) spacecraft are almost always charged to values that make measuring the cold-ion properties very difficult and (2) spacecraft surfaces exposed to sunlight and bombarded by energetic particles emit copious amounts of low-energy secondary and photoelectrons that blind the measurement of magnetospheric cold electrons.
  
Yet, the cold ~eV plasma plays multiple roles in magnetospheric dynamics (see Table 1). All of the magnetosphere’s cold ions flow to the dayside magnetopause, where the cold ions can reduce solar-wind/magnetosphere coupling by mass-loading dayside reconnection. The presence of cold cloak and CHEX ions when magnetospheric convection slows down can increase the early-time refilling rate of the plasmasphere. Cold ions and cold electrons can affect waves and wave-particle interactions by changing (1) the resonant conditions between particles and waves, (2) the wave growth rates, (3) the saturation level of the waves, and (4) wave-particle diffusion coefficients, all with strong implications on the dynamics of plasma sheet, ring current, and radiation belts. The low-energy oxygen of the cloak drastically changes ULF frequencies, which impacts the radial diffusion of energetic populations. Cold plasma has repeatedly been implicated for the spatial structuring of diffuse and pulsating aurora. See Table 1 for some connections between cold plasma populations and known impacts in magnetospheric physics.
+
Yet, the cold plasma plays multiple roles in magnetospheric dynamics (see Table 1). All of the magnetosphere’s cold ions flow to the dayside magnetopause, where the cold ions can reduce solar-wind/magnetosphere coupling by mass-loading dayside reconnection. The presence of cold cloak and CHEX ions when magnetospheric convection slows down can increase the early-time refilling rate of the plasmasphere. Cold ions and cold electrons can affect waves and wave-particle interactions by changing (1) the resonant conditions between particles and waves, (2) the wave growth rates, (3) the saturation level of the waves, and (4) wave-particle diffusion coefficients, all with strong implications on the dynamics of plasma sheet, ring current, and radiation belts. The low-energy oxygen of the cloak drastically changes ULF frequencies, which impacts the radial diffusion of energetic populations. Cold plasma has repeatedly been implicated for the spatial structuring of diffuse and pulsating aurora. See Table 1 for some connections between cold plasma populations and known impacts in magnetospheric physics.
  
 
We cannot understand the full complexity of the magnetospheric system until we can
 
We cannot understand the full complexity of the magnetospheric system until we can

Revision as of 17:02, 22 July 2020

Co-chairs

Gian Luca Delzanno (Los Alamos National Laboratory), Natalia Buzulukova (Goddard Space Flight Center), Barbara Giles (Goddard Space Flight Center), Roger Varney (SRI International), Joe Borovsky (Space Science Institute).

Research area

The cold plasma impacts all the research areas of GEM but a significant focus will be on ‘Inner Magnetosphere (IMAG)’ because of the critical role of waves and wave-particle interactions in magnetospheric dynamics.

Description

The cold (<1 keV) particle populations that exist in the magnetosphere (cf. Table 1) include (1) plasmaspheric ions (including the plume), (2) plasmaspheric electrons (including the plume), (3) cloak ions, (4) oxygen torus, (5) cloak electrons, (6) outflowing cold electrons, (7) outflowing cold ions and (8) charge-exchange-byproduct cold protons (CHEX protons). Outflowing (from the ionosphere) cold electrons are anticipated for the maintenance of charge neutrality in the magnetosphere: two places where they should occur are (a) in the post-midnight to dawn region where the electron plasma sheet precipitates away to make diffuse aurora and (b) at the inner edge of the electron plasma sheet where (owing to gradient-curvature drift effects) the ion plasma sheet flows radially Earthward while the electron plasma sheet flows eastward. There are also plasmaspheric-refilling cold-ion and cold-electron outflows into open-drift-trajectory flux tubes on the dayside.

While the hot (ring current/plasma sheet) and energetic (radiation belts) populations have received a lot of attention because of their potential harm to space infrastructure, the cold-plasma populations are the least studied so that in some cases they have been referred to as the ‘hidden populations’. This is because (1) spacecraft are almost always charged to values that make measuring the cold-ion properties very difficult and (2) spacecraft surfaces exposed to sunlight and bombarded by energetic particles emit copious amounts of low-energy secondary and photoelectrons that blind the measurement of magnetospheric cold electrons.

Yet, the cold plasma plays multiple roles in magnetospheric dynamics (see Table 1). All of the magnetosphere’s cold ions flow to the dayside magnetopause, where the cold ions can reduce solar-wind/magnetosphere coupling by mass-loading dayside reconnection. The presence of cold cloak and CHEX ions when magnetospheric convection slows down can increase the early-time refilling rate of the plasmasphere. Cold ions and cold electrons can affect waves and wave-particle interactions by changing (1) the resonant conditions between particles and waves, (2) the wave growth rates, (3) the saturation level of the waves, and (4) wave-particle diffusion coefficients, all with strong implications on the dynamics of plasma sheet, ring current, and radiation belts. The low-energy oxygen of the cloak drastically changes ULF frequencies, which impacts the radial diffusion of energetic populations. Cold plasma has repeatedly been implicated for the spatial structuring of diffuse and pulsating aurora. See Table 1 for some connections between cold plasma populations and known impacts in magnetospheric physics.

We cannot understand the full complexity of the magnetospheric system until we can

  1. reliably measure the full properties of the cold ions and electrons,
  2. learn what controls these properties, and
  3. learn all of the impacts of the cold populations.

We also need to include all of the related couplings into global models. This FG is proposed to advance our understanding of the impact of the cold particle populations in magnetospheric physics, from both theoretical/modeling and observational perspectives. The cold plasma represents a clear outstanding issue that needs to be addressed to make progress towards a full understanding of magnetospheric dynamics.

Table 1. Cold plasma populations and their known effect on the Earth's magnetosphere.
Cold Population Impact on the Magnetosphere
Plasmasphere ions Alter ULF frequency and radial diffusion of energetic electrons and ions
Alter EMIC scattering of electron radiation belt
Plasmasphere electrons Alter HISS decay of radiation-belt electrons
Create whistler ducts
Plasmapause HISS-chorus boundary
Site of enhanced ULF activity
Plasmaspheric plume ions Reduce the dayside reconnection rate
Alter Hall microphysics of dayside reconnection
Alter EMIC scattering of outer electron radiation belt
Cloak ions Alter ULF frequency and radial diffusion of energetic electrons and ions
Reduce the dayside reconnection rate
Alter Hall microphysics of dayside reconnection
Alter EMIC scattering of electron radiation belt
Reduce electron-plasma-sheet-driven spacecraft charging
Reduce threshold for Kelvin-Helmholtz on magnetopause
Cloak electrons Alter chorus and affect electron-radiation-belt energization
Structured dawnside cold electrons Produce spatial structure of (a) chorus-wave amplitudes and (b) the pulsating aurora
Charge-exchange-byproduct protons Alter Hall microphysics of dayside reconnection
May increase early-time plasmaspheric refilling rate
Alter EMIC scattering of electron radiation belt
Ionospheric ion outflows in magnetotail Alter Hall microphysics of magnetotail reconnection
Mass-loading of magnetotail reconnection
Alter magnetotail tearing instability
Ionospheric electron outflows Alter chorus properties

Specific goals

The overarching goals of the FG are to make scientific progress on understanding the impact of the cold plasma in magnetospheric physics and the implementation of those impacts into global models.

The specific goals are to

  1. bring together theoretical and observational knowledge to assess the most important impacts associated with the cold plasma in the magnetospheric system;
  2. determine what is known and what is unknown from an observational point of view and the related open scientific questions;
  3. plan data-analysis and modeling studies that are needed to gain critical understanding of cold populations and their controlling factors;
  4. determine what measurements are necessary to resolve these open scientific questions, including possibly the development of future instrumentation concepts and future mission concepts;
  5. determine how to fill in the gaps, including how to include those impacts into global simulation models. Possible ideas include developing empirical/simplified models that capture a specific cold-plasma effect (i.e., for instance, using simulation codes to understand and parametrize the impact of cold-plasma parameters on the saturation amplitude of various waves in the inner magnetosphere for use in ray-tracing and ring-current models), develop efficient computational strategies to couple plasmaspheric models/codes into inner magnetospheric models and develop empirical geomagnetically-driven or solar-wind-driven models for the properties of the plasma cloak or the CHEX-proton population that could be added to global simulation models.

The concrete deliverables of the FG will be a review paper that describes the progress made on all the goals discussed above and a journal special issue on the importance of the various cold populations.

EVENTS IN 2020

Session at CEDAR 2020

Title: Cold Plasma Populations Throughout the Geospace System

Date: Friday, June 26th, 11:00 AM - 1:00 PM MDT

Organizers: Roger Varney, Gian Luca Delzanno

Link: http://cedarweb.vsp.ucar.edu/wiki/index.php/2020_Workshop:Cold_Plasma

Sessions at Virtual GEM 2020

Several events are organized at GEM!

1) IMAG tutorial

  • Date: Tuesday, July 21st, 11:00 AM - 11:45 AM EDT
  • Speaker: Rick Chappell, Vanderbilt University
  • Title: The Impact of Ionospheric Plasma on the Magnetosphere

2) Focus Group discussion on planning activities for the next years

  • Date: Thursday, July 23rd, 1:00 PM - 2:30 PM EDT
  • Structure of the session:
  1. 1:00 PM - 1:05 PM. Short introduction on the goals of the Focus Group;
  2. 1:05 PM - 1:20 PM. Scene-setting talk by Elena Kronberg: 'Cold plasma particle populations'
  3. 1:20 PM - 1:35 PM. Scene-setting talk by Thom Moore: 'Cold Plasma Impacts (on Magnetospheric Physics)'
  4. 1:35 PM - 2:30 PM. Open discussion
  • Details:

Contributed talks are welcome as part of the discussion. They will be limited to one-slide/5-minutes per contribution and we will keep the list of contributions on the FG website. Please frame your contribution around one of the following discussion topics:

  1. What are the open questions associated with the cold-plasma in magnetospheric physics?
  2. What kind of measurements are necessary to fully understand the role of the cold plasma in magnetospheric physics?
  3. How do we include the impact of the cold-plasma in magnetospheric modeling, including global codes?
  4. What kind of activities would you like to see carried out in this cold-plasma FG?

Please contact Gian Luca Delzanno (delzanno@lanl.gov) to arrange your contribution!

  • Contributed talks:
  • What are the open questions associated with the cold-plasma in magnetospheric physics?
    1. Jerry Goldstein, SWRI, Open Questions About Cold Plasma
    2. Naritoshi Kitamura, University of Tokyo, Cold ion outflow and the transport to the inner magnetosphere
    3. Shannon Hill, University of Michigan, Cold Plasma Heating by Waves in the Inner Magnetosphere
  • What kind of measurements are necessary to fully understand the role of the cold plasma in magnetospheric physics?
    1. Jerry Goldstein, SWRI, What Measurements are Needed to Answer Open Questions About Cold Plasma?
    2. Justin Lee, Aerospace, Directly measuring cold ions for EMIC wave studies


  • How do we include the impact of the cold-plasma in magnetospheric modeling, including global codes?
  • What kind of activities would you like to see carried out in this cold-plasma FG?

3) Joint session on the impact of the cold plasma in the inner magnetosphere

with the following FGs

  • Self-Consistent Inner Magnetospheric Modeling
  • System Understanding of Radiation Belt Particle Dynamics through Multi-spacecraft and Ground-based Observations and Modeling
  • Date: Thursday, July 23rd, 3:00 PM - 4:30 PM EDT
  • Structure of the session:
  1. 3:00 PM - 3:15 PM. Scene-setting talk by Dan Welling: 'A Global Modeler's View of the Importance of Cold Ion Populations'
  2. 3:15 PM - 3:30 PM. Scene-setting talk by Lynn Kistler: 'Warm (<1 keV) plasma in the inner magnetosphere: characteristics and effects'
  3. 3:30 PM - 4:30 PM. Contributed talks and open discussion
  • Details:

Contributed talks will be limited to 2-3 slides per contribution and we will keep the list of contributions on the FG website. Please contact Gian Luca Delzanno (delzanno@lanl.gov) to arrange your contribution!

Some topics of interest:

  1. wave-particle interaction physics: how cold plasma affects wave properties, including heating
  2. outflows, warm cloak, plumes
  3. pulsating aurora
  4. how local/microscopic codes can inform global codes
  • Contributed talks:
  1. Mike Henderson, Los Alamos National Laboratory, Observations of STEVE-like emissions and potential Generation Mechanism
  2. Xiangning Chu, LASP, Acceleration of cold ions and electrons at a sharp plasmapause boundary
  3. Oleksiy Agapitov, University of California Berkeley, The effects of cold plasma density variations for timescales of electron quasi‐linear diffusion by chorus and hiss waves
  4. Suk-Bin Kang, NASA Goddard Space Flight Center, EMIC waves modeling and cold plasma parameters
  5. Ying Zou, University of Alabama Huntsville, Geospace plume and its impact on dayside reconnection