Hot Plasma Composition Analyzer for the Magnetospheric Multiscale Mission

Abstract

This paper describes the science motivation, measurement objectives, performance requirements, detailed design, approach and implementation, and calibration of the four Hot Plasma Composition Analyzers (HPCA) for the Magnetospheric Multiscale mission. The HPCA is based entirely on electrostatic optics combining an electrostatic energy analyzer with a carbon-foil based time-of-flight analyzer. In order to fulfill mission requirements, the HPCA incorporates three unique technologies that give it very wide dynamic range capabilities essential to measuring minor ion species in the presence of extremely high proton fluxes found in the region of magnetopause reconnection. Dynamic range is controlled primarily by a novel radio frequency system analogous to an RF mass spectrometer. The RF, in combination with capabilities for high TOF event processing rates and high current micro-channel plates, ensures the dynamic range and sensitivity needed for accurate measurements of ion fluxes between ∼1 eV and 40 keV that are expected in the region of In order to calibrate the four HPCA instruments we have developed a unique ion calibration system. The system delivers a multi-species beam resolved to M/ M ∼ 100 and current densities between 0.05 and 200 pA/cm 2 with a stability of ±5 %. The entire system is controlled by a dedicated computer synchronized with the HPCA ground support equipment. This approach results not only in accurate calibration but also in a comprehensive set of coordinated instrument and auxiliary data that makes analysis straightforward and ensures archival of all relevant data.

Magnetic reconnection and modification of the Hall physics due to cold ions at the magnetopause

“…At low latitudes, cold ions are very common, have a smaller gyroradius than the hot magnetosheath and magnetospheric ions, and remain magnetized down to smaller spatial scales. The physics at these scales is relevant for particle energization and the reconnection rate [Drake et al, 2008;Yamada et al, 2010;Liu et al, 2014]. This is somewhat similar to the larger scale introduced by heavy ions [Shay and Swisdak, 2004;Markidis et al, 2011].…”

Magnetospheric Multiscale Overview and Science Objectives

“…MMS will use an Active Spacecraft Potential Control device (ASPOC), which emits indium ions to neutralize the photoelectron current and keep the spacecraft from charging to more than four volts positive (Torkar et al 2014). Because physical processes in the ion diffusion region depend sensitively on ion mass, MMS includes a new-generation Hot Plasma Composition Analyzer (HPCA) (Burch et al 2005;Young et al 2014), which corrects problems with high proton fluxes that have prevented accurate ion-composition measurements near the dayside magnetospheric boundary (Phan et al 2003).…”

“…Also listed in Table 1 is the SOC (Science Operations Center). Details of these mission elements are provided in other papers in this issue (Torbert et al 2014;Ergun 2014;Russell et al 2014;Lindqvist et al 2014;Pollock 2015;Mauk et al 2014;Blake 2015;Young et al 2014;Torkar et al 2014). The arrangement of the scientific payload of each spacecraft is shown in Fig.…”

Near-Earth plasma sheet boundary dynamics during substorm dipolarization

“…Here, the electric field (panel j and blue traces in panels g-i) and FPI ion velocity data (red traces in panels g-i) are averaged to 1-Hz resolution (i.e., about the ion-gyro frequency). Proton velocity data obtained by the Hot Plasma Composition Analyzer (HPCA) instrument (Young et al 2014) are shown in 10-s resolution as black curves in panels g-i. The transient dipolarizations and the crossings of the current layers are associated with enhancements in the equatorward/Earthward plasma flows and in the dawn-to-dusk electric field (negative E D ), as represented in Fig.…”