In-flight calibration of the Cluster PEACE sensors

N Doss,Y Bogdanova,R J Wilson,D Kataria,B Mihaljčić,I Rozum,G Watson,A N Fazakerley,A D Lahiff

doi:10.5194/gi-3-59-2014

Abstract

Abstract. The Plasma Electron and Current Experiment (PEACE) instruments operate on all four of the Cluster spacecraft and measure the 3-D velocity distribution of electrons in the energy range from 0.59 eV to 26.4 keV during each spacecraft spin. Pitch angle distributions and moments of the velocity distribution are also produced. As the mission has progressed, the efficiency of the detectors has declined. Several factors may play a role in this decline such as exposure to radiation, high electron fluxes and spacecraft thruster firings. To account for these variations, continuous in-flight calibration work is essential. The purpose of this paper is to describe the PEACE calibration parameters, focussing in particular on those that vary over time, and to describe the methods which are used to determine their evolution.

Highlights

A detailed description of the Plasma Electron and Current Experiment (PEACE) instrument is not provided here but can be found in Johnstone et al (1997) and Fazakerley et al (2010a).Each of the Cluster spacecraft carries an identical PEACE instrument which consists of two sensors and a data processing unit
The alpha factors determined from PEACE–WHISPER comparisons include the correction required to refine the value of the time-independent ε0 calibration parameter determined in ground tests
There are several features that can be seen in these plots which require further discussion: 1. micro-channel plate (MCP) operational voltage level raises: due to decline in MCP efficiency over time, the operational MCP voltage levels on all sensors have been raised at various times throughout the mission in order to recover a desired sensitivity level

Summary

Introduction

Each of the Cluster spacecraft carries an identical PEACE instrument which consists of two sensors and a data processing unit. Both sensors are capable of covering the full energy range of the instrument, but each sensor usually covers about 70 % of the instrument energy range in any given spin. The LEEA (Low Energy Electron Analyser) sensor has a smaller geometric factor appropriate for the higher fluxes that are normally found at the lower energies such as in the solar wind and magnetosheath. The HEEA (High Energy Electron Analyser) sensor has a larger geometric factor better suited for the weaker fluxes seen in the magnetosphere. Used together the sensors can cover the full energy range every spin

Objectives

Results

Discussion

Conclusion