The Low‐Energy Neutral Imager (LENI)

Abstract

To achieve breakthroughs in the areas of heliospheric and magnetospheric energetic neutral atom (ENA) imaging, a new class of instruments is required. We present a high angular resolution ENA imager concept aimed at the suprathermal plasma populations with energies between 0.5 and 20 keV. This instrument is intended for understanding the spatial and temporal structure of the heliospheric boundary recently revealed by Interstellar Boundary Explorer instrumentation and the Cassini Ion and Neutral Camera. The instrument is also well suited to characterize magnetospheric ENA emissions from low‐altitude ENA emissions produced by precipitation of magnetospheric ions into the terrestrial upper atmosphere, or from the magnetosheath where solar wind protons are neutralized by charge exchange, or from portions of the ring current region. We present a new technique utilizing ultrathin carbon foils, 2‐D collimation, and a novel electron optical design to produce high angular resolution (≤2°) and high‐sensitivity (≥10−3 cm2 sr/pixel) ENA imaging in the 0.5–20 keV energy range.

Soft X‐ray and ENA Imaging of the Earth's Dayside Magnetosphere

“…Recently, Westlake et al. (2016) suggested a new concept for a low‐ENA instrument that provides less than 2° angular resolution for the 0.5–20 keV energy range with high sensitivity () and high energy resolution . Its cadence depends on multiple factors (e.g., the spacecraft spin period, its field of view, number of energy channels, and signal strength) and can be adjusted to meet science requirements during a mission concept study.…”

“…With the technological advancement of Westlake et al (2016) and well-thought-out mission planning, the 1° angular resolution and 1 min cadence used in our study may be achieved in the near future.…”

“…The two ENA cameras on IBEX have 3.5°-7° angular resolution, measuring low ENAs (0.01-2 keV) and high ENAs (0.54-6 keV) (Funsten et al, 2009;Fuselier et al, 2009). Recently, Westlake et al (2016) suggested a new concept for a low-ENA instrument that provides less than 2° angular resolution for the 0.5-20 keV energy range with high sensitivity (   3 2 10 cm sr/pixcel) and high energy reso-…”

The Big Picture: Imaging of the Global Geospace Environment by the TWINS Mission

“…In the future, budgets should include the resources needed to make inversions and other higher‐level science products routinely available. Next‐generation ENA imager. Previous or existing ENA imagers are large and heavy (Westlake et al, ). Imagers capable of measuring ENAs below 10 keV are either 1‐D/linear spectrometers like TWINS, or single‐pixel cameras like the Interstellar Boundary Explorer (McComas, Allegrini, Bochsler, et al, ).…”

“…Next-generation ENA imager. Previous or existing ENA imagers are large and heavy (Westlake et al, 2016).…”