Imaging the Global Distribution of Plasmaspheric Oxygen

Abstract

This paper investigates the potential for 83.4 nm imaging of the plasmaspheric dense oxygen torus, using simple models for core plasma density and composition to constrain a simulated image code. We derive the requirements for plasmaspheric O+ imaging, and the expected performance of an imager based on a slightly modified version of the IMAGE extreme ultraviolet camera. We find that such an imager can achieve a sensitivity of 0.69(s R pixel)−1, sufficient to capture the dense torus 83.4 nm signal with 25 min integration time. The background rejection ratios for this design are 1.5 × 10−4 at 58.4 nm and 7.4 × 10−8 for Lyman‐α. We discuss the effects of ion temperature and motion, and O++ glow. We compute simulated O+ images of the formation and global distribution of the dense torus. We also examine the possibility of direct observation of oxygen outflow from the ionosphere.

Oxygen torus and its coincidence with EMIC wave in the deep inner magnetosphere: Van Allen Probe B and Arase observations

“…11, the crescent-shaped oxygen torus is depicted to have ~ 9 h extent in MLT (yellow area), but its actual longitudinal extent is not yet known from these two-point measurements. Future studies to reveal the longitudinal extent of the oxygen torus may include global imaging of emission from O + ions by an EUV camera carried by satellites (Goldstein et al 2018) or a numerical simulation of low energy O + ions traveling from the ionosphere to the inner magnetosphere in realistic electric and magnetic field models. When Probe B identified the oxygen torus in the morning, the H + band EMIC wave was found at approximately 4.5 Hz (red zigzag line).…”

Low‐Energy (<keV) O+ Ion Outflow Directly Into the Inner Magnetosphere: Van Allen Probes Observations

“…Because heavier ions have smaller tailward velocities than lighter ones, they end up being transported closer to Earth; thus, an area with high concentration of the ionospheric O + ions is formed outside the plasmasphere during the storm main phase (e.g., Moore et al, ; Nosé et al, ). Goldstein et al () illustrated how imaging of plasmaspheric dense oxygen and ionospheric outflow with and Extreme Ultraviolet (EUV) imager could potentially provide an answer to when, where, and how the O + torus forms.…”

“…Because heavier ions have smaller tailward velocities than lighter ones, they end up being transported closer to Earth; thus, an area with high concentration of the ionospheric O + ions is formed outside the plasmasphere during the storm main phase (e.g., Moore et al, 2001;Nosé et al, 2015). Goldstein et al (2018) illustrated how imaging of plasmaspheric dense oxygen and ionospheric outflow with and Extreme Ultraviolet (EUV) imager could potentially provide an answer to when, where, and how the O + torus forms. Nosé et al (2015) inferred the formation of O + torus during a geomagnetic storm, by calculating the average ion mass using the resonant frequencies of standing Alfven waves and upper hybrid resonance band obtained by the Van Allen Probes.…”

The Cold Ion Population at Geosynchronous Orbit and Transport to the Dayside Magnetopause: September 2015 to February 2016

“…These ions are predominately H + , but there is a relatively large concentration of He + in the plasmasphere. Previous work has revealed the importance of this population in terms of its role in (i) mass loading of the dayside reconnection site (Borovsky & Denton, , ; Borovsky et al, ; Fuselier et al, , ; Walsh et al, ); contributing to wave‐growth and wave‐particle interactions in general (Borovsky, Friedel, et al, ; Blum et al, ; MacDonald et al, , ; Posch et al, ); refilling of the plasmasphere and warm plasma cloak following intervals of enhanced magnetospheric convection (Carpenter & Lemaire, ; Chappell et al, ; Denton & Borovsky, ; Su et al, ); and (iv) the total inertia in the magnetospheric system (Denton et al, ; Goldstein et al, ).…”

“…Cold ions (<1 eV to approximately tens of electron volts) in the Earth's plasmasphere are the primary constituent contributing to the mass density in the Earth's magnetosphere with a total mass ~10 2 –10 3 metric tons (Borovsky & Denton, ; Goldstein et al, ). These ions are predominately H + , but there is a relatively large concentration of He + in the plasmasphere.…”