The Calibration results of the Flight model of the Jovian Electron and Ion spectrometer for the Jupiter Icy Moons Explorer and their link to Mercury

<p>&#160;</p> <div class="page" role="region" data-page-number="1" aria-label="Page 1" data-loaded="true"> <div class="textLayer"><strong><span dir="ltr" role="presentation">Abstract</span></strong><br role="presentation" /><span dir="ltr" role="presentation">Electrostatic analyzers are key instruments for under</span><span dir="ltr" role="presentation">standing magnetospheric plasma. Their measurements</span><br role="presentation" /><span dir="ltr" role="presentation">also contribute to the determination of the surface </span><span dir="ltr" role="presentation">and interior composition of moons and planets. They</span><br role="presentation" /><span dir="ltr" role="presentation">measure properties in particle charge, energy and 3D </span><span dir="ltr" role="presentation">velocity vectors of electrons and ions. Calibration of</span><br role="presentation" /><span dir="ltr" role="presentation">these instruments is challenging.</span> <span dir="ltr" role="presentation">Ground facilities </span><span dir="ltr" role="presentation">can not reproduce the electromagnetic and radiation</span><br role="presentation" /><span dir="ltr" role="presentation">background of Jupiter.</span> <span dir="ltr" role="presentation">Also the particle flows and, </span><span dir="ltr" role="presentation">their full energy- and 3D flow spectrum over the</span><br role="presentation" /><span dir="ltr" role="presentation">complete field of view of a spherical analyzers can </span><span dir="ltr" role="presentation">not be produced by our facilities.</span> <span dir="ltr" role="presentation">Instead beams</span><br role="presentation" /><span dir="ltr" role="presentation">larger than the field of view of at least one detector </span><span dir="ltr" role="presentation">channel reproduce step-vise parts of the parameter</span><br role="presentation" /><span dir="ltr" role="presentation">spaces of the expected spectrum.</span> <span dir="ltr" role="presentation">By combining </span><span dir="ltr" role="presentation">simulations, ground based calibration and in-flight</span><br role="presentation" /><span dir="ltr" role="presentation">calibration, the reliability of the calibration can be </span><span dir="ltr" role="presentation">increased.</span> <span dir="ltr" role="presentation">The calibration of the flight model of</span><br role="presentation" /><span dir="ltr" role="presentation">the The Jupiter Electron and Ion Spectrometer (JEI) </span><span dir="ltr" role="presentation">showed good agreement with the simulations, except</span><br role="presentation" /><span dir="ltr" role="presentation">for a significant discrepancy in azimuth resolution </span><span dir="ltr" role="presentation">and the geometric factor at high pole inclinations.</span><br role="presentation" /><span dir="ltr" role="presentation">After a final upgrade of the test bench, </span><span dir="ltr" role="presentation">we will allow for better comparison of results between</span><br role="presentation" /><span dir="ltr" role="presentation">The Jupiter Icy Moons Explorer (JUICE) and the </span><span dir="ltr" role="presentation">BepiColombo missions by cross-calibrating JEI and</span><br role="presentation" /><span dir="ltr" role="presentation">the The Planetary Ion Camera (PICAM).</span></div> <div class="textLayer">&#160;</div> </div> <p><span dir="ltr" role="presentation"><img src="" alt="" width="371" height="448" /></span></p> <div class="page" role="region" data-page-number="2" aria-label="Page 2" data-loaded="true"> <div class="textLayer"> <div class="textLayer"><strong><span dir="ltr" role="presentation">Plain Language Summary</span></strong></div> <div class="textLayer">&#160;</div> <div class="textLayer"><span dir="ltr" role="presentation">Charged particles interact with magnetic field, plan</span><span dir="ltr" role="presentation">ets and moons. Measuring the properties of these par-</span><br role="presentation" /><span dir="ltr" role="presentation">ticles helps to understand the interaction and allows </span><span dir="ltr" role="presentation">to analyze the surfaces and interiors of planets and</span><br role="presentation" /><span dir="ltr" role="presentation">moons as a result of their interaction with their sur</span><span dir="ltr" role="presentation">rounding magnetic field. Unfortunately, calibration of</span><br role="presentation" /><span dir="ltr" role="presentation">these instruments is complicated because accelerators </span><span dir="ltr" role="presentation">only produce a small spectrum of the target particle</span><br role="presentation" /><span dir="ltr" role="presentation">streams at once. In order to improve the results, cal</span><span dir="ltr" role="presentation">ibration measurements on the ground are combined</span><br role="presentation" /><span dir="ltr" role="presentation">with simulations and later with calibrations during the </span><span dir="ltr" role="presentation">mission using known plasma, like the solar wind. The</span><br role="presentation" /><span dir="ltr" role="presentation">calibration for JEI agreed with the simulations, except </span><span dir="ltr" role="presentation">for high polar angles</span><span dir="ltr" role="presentation">(Fig.</span> 1<span dir="ltr" role="presentation">.)</span></div> <div class="textLayer"><span dir="ltr" role="presentation">This is due to the different beams </span><span dir="ltr" role="presentation">used for calibration and simulation.&#160;</span></div> <div class="textLayer">&#160;</div> <div class="textLayer"><span dir="ltr" role="presentation"><img src="" alt="" width="712" height="449" /></span></div> </div> <div class="textLayer"><strong><span dir="ltr" role="presentation">1</span> <span dir="ltr" role="presentation">Introduction</span></strong></div> <div class="textLayer"><br role="presentation" /><span dir="ltr" role="presentation">JUICE will explore the Jovian magnetosphere and </span><span dir="ltr" role="presentation">three of the four Galilean moons.</span> <span dir="ltr" role="presentation">After several fly-</span><br role="presentation" /><span dir="ltr" role="presentation">bys of Europa and Callisto it will eventually enter orbit </span><span dir="ltr" role="presentation">around Ganymede. JEI is part of The Particle Environ-</span><br role="presentation" /><span dir="ltr" role="presentation">ment Package (PEP) on JUICE. JEI will measure electron and </span><span dir="ltr" role="presentation">ion distributions in the range from a few eV to a few</span><br role="presentation" /><span dir="ltr" role="presentation">MeV with almost full hemispheric coverage</span><span dir="ltr" role="presentation">.</span><br role="presentation" /><span dir="ltr" role="presentation">PICAM on BepiColombo has overlaps with JEI in </span><span dir="ltr" role="presentation">its energy range from</span> <span dir="ltr" role="presentation">1 eV</span> <span dir="ltr" role="presentation">to</span> <span dir="ltr" role="presentation">3 keV</span><span dir="ltr" role="presentation">.</span> <span dir="ltr" role="presentation">While mea-</span><br role="presentation" /><span dir="ltr" role="presentation">suring ions only, PICAM has additionally a time-of-</span><span dir="ltr" role="presentation">flight unit, which allows to resolve incoming particles</span><br role="presentation" /><span dir="ltr" role="presentation">at a</span> <span dir="ltr" role="presentation">m/&#948;m</span> <span dir="ltr" role="presentation">ratio of 100.</span> <span dir="ltr" role="presentation">There are links be</span><span dir="ltr" role="presentation">tween Mercury and Ganymede. Besides being similar</span><br role="presentation" /><span dir="ltr" role="presentation">size, they are the only known solid objects in the so</span><span dir="ltr" role="presentation">lar system other than Earth that have intrinsic mag-</span><br role="presentation" /><span dir="ltr" role="presentation">netic fields.</span> <span dir="ltr" role="presentation">While the magnetic moments are simi</span><span dir="ltr" role="presentation">lar in strength, </span><span dir="ltr" role="presentation">Mercury is exposed to a supersonic plasma</span></div> <div class="textLayer"><span dir="ltr" role="presentation"> of </span><span dir="ltr" role="presentation">the solar wind while Ganymede is only surrounded by the subsonic </span><span dir="ltr" role="presentation">plasma of Jupiter&#8217;s magnetosphere.&#160;</span></div> <div class="textLayer"><br role="presentation" /><strong><span dir="ltr" role="presentation">2. Results</span></strong></div> <div class="textLayer">&#160;</div> <div class="textLayer"><br role="presentation" /><span dir="ltr" role="presentation">For all JEI models, including the qualification model, </span><span dir="ltr" role="presentation">the polar-, energy- and azimuth resolution could be</span><br role="presentation" /><span dir="ltr" role="presentation">measured in agreement with the accompanying sim</span><span dir="ltr" role="presentation">ulations and within the specifications of the original</span><br role="presentation" /><span dir="ltr" role="presentation">proposal. The resolutions and deflector response are </span><span dir="ltr" role="presentation">plotted in Fig. 2. Only the azimuth resolution deviates</span><br role="presentation" /><span dir="ltr" role="presentation">at higher polar inclinations from the simulations. The </span><span dir="ltr" role="presentation">deviation directly affects the geometric factor, which</span><br role="presentation" /><span dir="ltr" role="presentation">differs over the polar inclinations in the same range.</span><br role="presentation" /><span dir="ltr" role="presentation">The deviation is suspected to be reasoned by the dif</span><span dir="ltr" role="presentation">ferent exposure of the sensor in the particle flow be-</span><br role="presentation" /><span dir="ltr" role="presentation">tween the simulations and the beam in the test facil</span><span dir="ltr" role="presentation">ity. Simulations and measurements with an off-center</span><br role="presentation" /><span dir="ltr" role="presentation">beam are currently conducted to confirm the cause.&#160;</span><br role="presentation" /><span dir="ltr" role="presentation">A slight coaxial misalignment between the inner and </span><span dir="ltr" role="presentation">outer spheres could be measured due to the deviations</span><br role="presentation" /><span dir="ltr" role="presentation">of the individual energy peaks of the channels.</span><br role="presentation" /><span dir="ltr" role="presentation">Currently the positing system is under replacement to </span><span dir="ltr" role="presentation">allow joint measurements of JEI and PICAM.</span> <div class="endOfContent">&#160;</div> </div> </div> <div class="page" role="region" data-page-number="3" aria-label="Page 3" data-loaded="true"> <div class="canvasWrapper"> <div class="ui-layout-east ui-layout-pane ui-layout-pane-east ui-layout-pane-hover ui-layout-pane-east-hover ui-layout-pane-open-hover ui-layout-pane-east-open-hover"> <div class="ng-scope"> <div class="pdf full-size"> <div class="pdf-viewer"> <div class="pdfjs-viewer pdfjs-viewer-outer"> <div class="pdfjs-viewer-inner" tabindex="0" role="tabpanel"> <div class="pdfViewer"> <div class="page" role="region" data-page-number="3" aria-label="Page 3" data-loaded="true"> <div class="textLayer"><strong><span dir="ltr" role="presentation">Acknowledgements</span></strong><br role="presentation" /><span dir="ltr" role="presentation">This works is supported by DLR grants 50QW1702</span><br role="presentation" /><span dir="ltr" role="presentation">and 50QJ1503.</span> <div class="endOfContent">&#160;</div> </div> </div> </div> </div> <div class="pdfjs-controls"> <div class="btn-group">&#160;</div> </div> </div> </div> </div> </div> </div> <div class="ui-layout-resizer-controls synctex-controls">&#160;</div> </div> <div class="textLayer">&#160;</div> </div> <div class="ui-layout-resizer-controls synctex-controls">&#160;</div>