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The THEMIS plasma instrument is designed to measure the ion and electron distribution functions over the energy range from a few eV up to 30 keV for electrons and 25 keV for ions. The instrument consists of a pair of “top hat” electrostatic analyzers with common 180°×6° fields-of-view that sweep out 4π steradians each 3 s spin period. Particles are detected by microchannel plate detectors and binned into six distributions whose energy, angle, and time resolution depend upon instrument mode. On-board moments are calculated, and processing includes corrections for spacecraft potential. This paper focuses on the ground and in-flight calibrations of the 10 sensors on five spacecraft. Cross-calibrations were facilitated by having all the plasma measurements available with the same resolution and format, along with spacecraft potential and magnetic field measurements in the same data set. Lessons learned from this effort should be useful for future multi-satellite missions.

Microchannel plates for spaceborne detectors need to be firmly gripped to survive vibration environments. A variety of materials commonly employed in the fabrication of microchannel plate retaining structures were studied. We present data on the frictional properties of microchannel plates and these materials to guide detector developers in choosing the proper gripping force for a given detector mass and peak acceleration.

The Medium Energy Neutral Atom (MENA) imager was developed in response to the Imaging from the Magnetopause to the Aurora for Global Exploration (IMAGE) requirement to produce images of energetic neutral atoms (ENAs) in the energy range from 1 to 30 keV. These images will be used to infer characteristics of magnetospheric ion distributions. The MENA imager is a slit camera that images incident ENAs in the polar angle (based on a conventional spherical coordinate system defined by the spacecraft spin axis) and utilizes the spacecraft spin to image in azimuth. The speed of incident ENAs is determined by measuring the time-of-flight (TOF) from the entrance aperture to the detector. A carbon foil in the entrance aperture yields secondary electrons, which are imaged using a position-sensitive Start detector segment. This provides both the one- dimensional (1D) position at which the ENA passed through the aperture and a Start time for the TOF system. Impact of the incident ENA on the 1D position-sensitive Stop detector segment provides both a Stop-timing signal and the location that the ENA impacts the detector. The ENA incident polar angle is derived from the measured Stop and Start positions. Species identification (H vs. O) is based on variation in secondary electron yield with mass for a fixed ENA speed. The MENA imager is designed to produce images with 8 4 angular resolution over a field of view 140 360, over an energy range from 1 keV to 30 keV. Thus, the MENA imager is well suited to conduct measurements relevant to the Earth's ring current, plasma sheet, and (at times) magnetosheath and cusp.

We demonstrate a multilayer circuit board that has two orthogonal serpentine delay lines on different layers to read out event positions from a microchannel plate (MCP). The top serpentine is directly bombarded by the MCP. The orthogonal buried serpentine receives its charge through thousands of vias that connect to the top surface. Event X and Y positions are decoded with a timing circuit for each axis. The spatial resolution is much finer than the via spacing because every event’s charge footprint spans several vias, and because the timing circuit senses the centroid of the event’s position on each delay line. This construction method eliminates fabrication problems encountered in previous multilayer designs and eliminates the need for crossed conducting fingers with their concomitant degradation of the otherwise excellent phase delay characteristic of serpentine delay lines. Performance data are presented for an anode of this new type. Formulas and graphs are given to assist in creating a variety of anodes of this type.

The MAVEN SupraThermal And Thermal Ion Compostion (STATIC) instrument is designed to measure the ion composition and distribution function of the cold Martian ionosphere, the heated suprathermal tail of this plasma in the upper ionosphere, and the pickup ions accelerated by solar wind electric fields. STATIC operates over an energy range of 0.1 eV up to 30 keV, with a base time resolution of 4 seconds. The instrument consists of a toroidal “top hat” electrostatic analyzer with a $360^{\circ} \times 90^{\circ}$ field-of-view, combined with a time-of-flight (TOF) velocity analyzer with $22.5^{\circ}$ resolution in the detection plane. The TOF combines a $-15~\mbox{kV}$ acceleration voltage with ultra-thin carbon foils to resolve $\mathrm{H}^{+}$ , $\mathrm{He}^{++}$ , $\mathrm{He}^{+}$ , $\mathrm{O}^{+}$ , $\mathrm{O}_{2}^{+}$ , and $\mathrm{CO}_{2}^{+}$ ions. Secondary electrons from carbon foils are detected by microchannel plate detectors and binned into a variety of data products with varying energy, mass, angle, and time resolution. To prevent detector saturation when measuring cold ram ions at periapsis ( $\sim10^{1 1}~\mbox{eV/cm}^{2}\,\mbox{s}\,\mbox{sr}\,\mbox{eV}$ ), while maintaining adequate sensitivity to resolve tenuous pickup ions at apoapsis ( $\sim10^{3}~\mbox{eV/cm}^{2}\,\mbox{s}\,\mbox{sr}\,\mbox{eV}$ ), the sensor includes both mechanical and electrostatic attenuators that increase the dynamic range by a factor of $10^{3}$ . This paper describes the instrument hardware, including several innovative improvements over previous TOF sensors, the ground calibrations of the sensor, the data products generated by the experiment, and some early measurements during cruise phase to Mars.