Simula'ons as a tool for higher mass resolu'on spectrometer: Lessons from exis,ng observa,ons

Transcription

1 Simula'ons as a tool for higher mass resolu'on spectrometer: Lessons from exis,ng observa,ons 1 G. Nicolaou, 1 M. Yamauchi, 1,2 H. Nilsson, 1 M. Wieser, 3 A. Fedorov, 1 D. R. Cas'llo and 2 L. Berčič Mo'va'on ESCAPE: M5 Mission Science Objective: How and at what rate is Earth slowly losing its atmosphere to space? Determine escape mechanisms Requirement High resolution measurements: Distinct ion species and their isotopes 1 Swedish Ins'tute of Space Physics (IRF), Kiruna, Sweden 2 Luleå University of Technology, Kiruna, Sweden 3 Ins'tut de Recherche en Astrophysique et Planetologie (IRAP), CNRS/Universite de Toulouse, Toulouse, France

2 Simula'ons as a tool for higher mass resolu'on spectrometer: Lessons from exis,ng observa,ons 1 G. Nicolaou, 1 M. Yamauchi, 1,2 H. Nilsson, 1 M. Wieser, 3 A. Fedorov, 1 D. R. Cas'llo and 2 L. Berčič Heritage ICA (Rosetta) and IMA (Mars Express/ Venus Express): Examples of successful separation of H2O, O, O2 and CO2 Modifica'ons NOIA (ESCAPE proposed mission) Geometrical modifications-electrostatic Analyser and magnets shape/size 1 Swedish Ins'tute of Space Physics (IRF), Kiruna, Sweden 2 Luleå University of Technology, Kiruna, Sweden 3 Ins'tut de Recherche en Astrophysique et Planetologie (IRAP), CNRS/Universite de Toulouse, Toulouse, France

3 Simula'ons as a tool for higher mass resolu'on spectrometer: Lessons from exis,ng observa,ons 1 G. Nicolaou, 1 M. Yamauchi, 1,2 H. Nilsson, 1 M. Wieser, 3 A. Fedorov, 1 D. R. Cas'llo and 2 L. Berčič Lessons from observa'ons Unwanted effects: Sector and mass channel cross-talk, contamination, noise More to be considered Different detector design Understand the nature of contamination how to remove or avoid Better calibration on response mass/sector sensi2vity knowledge 1 Swedish Ins'tute of Space Physics (IRF), Kiruna, Sweden 2 Luleå University of Technology, Kiruna, Sweden 3 Ins'tut de Recherche en Astrophysique et Planetologie (IRAP), CNRS/Universite de Toulouse, Toulouse, France

4 The Ion Composi'on Analyser (ICA) on ROSETTA and the Ion Mass Anylyser (IMA) on MEX/VEX ICA/IMA design and principle Credit : E. Behar (Le\) ICA/IMA instrument cross sec2on. Ion trajectories through the instrument are shown. (middle) azimuth sectors orienta2on and (right) eleva2on direc2on detected during the eleva2on scans

5 Mass detec'on Deflectors: Eleva2on selec2on ESA: E/q selec2on Magnets: m/q selec2on The MCP is divided in 16 azimuth sectors and 32 mass rings: For the same E/q heavier species land closer to the center

6 Simula'ons of ICA/IMA response Goal: to achieve as realis2c simula2on as possible SIMION: 3-d ion tracing souware The actual flight model design files are used Studied: posi2on of different species in the MCP a) Instrument design in SIMION software, b) cross section of instrument and c) top vie if MCP in SIMION ion tracing software Purpose: I. compare with flight data II. Extrapolate to low energies III. Modifica2ons for bezer performance

7 Compared to calibra'on ICA calibra'on: available for one sector few species Energies>300eV ICA simula'on: Cannot resolve sector differences Uniform response Perfect magnets

8 Direc'ons for improvement Geometrical modifica2ons for bezer mass peak separa2on (introduced by Nicolaou et al.,2016) a) Cross sec2on of a simplified ICA-IMA like design with spherical ESA and a modified designed with toroidal ESA, and longer magnets. Trajectories of different species through the magnets are also shown. b) top view of the detector for the two designs. The distribu2ons show bezer sepera2on for the modified model.

9 Proposed instrument: Nitrogen-Oxygen Ion Detector (NOID) Instrument for ESCAPE proposal (ESA s M5) Based on ICA/IMA design (geometrical modifica'ons only) More to be consider: narrower sectors, magnets of different shape, MCP of different shape (Nicolaou et al., 2016)

10 Flight data: Lessons we learned Mass peaks can be successfully fized to the IMA-MEX data: From Cas'llo et al., 2017 Gaussian fieng does not work all the 2me!!!

11 Flight data: Lessons we learned ICA data is more challenging: Broader signal Many possible species from the comet Many heavy species are recorded in low E/q Strong mass bin and azimuth cross talk Limited calibra2on (not at all <300eV/q)

12 Flight data: Lessons we learned Challenges Mass rings (bins) cross talk Inac2ve mass rings (give no signal) Non uniform background

13 Flight data: Lessons we learned Non-uniform response Noise analysis Energies where nosignal is expected would give ideally uniform background Not the case Each anode has different sensi2vity?

14 Flight data: Lessons we learned Azimuth sectors cross-talk: Selected periods when solar wind beam illuminates specific sector Find extremely correlated signal in other sectors Quan2fy the cross-talk and remove (already done for protons)

15 Flight data: Lessons we learned ghost counts: par2cles scazered over the mass anodes ghost counts pollute the informa2on of ion mass ghost counts have been removed in order to fit the IMA data mass peaks Not clean clean

16 Conclusions Preliminary geometrical modifica'ons of the exis'ng design are promising for higher mass resolu'on Flight data indicate more problems: i) mass/azimuth cross-talk ii) Contamina,on iii) Non uniform response (diff. efficiency of sectors and anodes) Direc'ons of improvement: i) Re-design sector/anode system ii) Understand the contamina,on iii) Calibrate the response in more detail

17 Thank you