Mercury Plasma Particle Experiments - Mass Spectrum Analyzer (MSA)

[Fig 37 from Saito et al., 2021]

Measurement Principle

The Mass Spectrum Analyzer (MSA) that is part of the MPPE consortium onboard Mio, measures mass resolved 3D distribution functions of ions from 1 eV/q up to 38 keV/q. As such, it allows us to investigate the magnetospheric plasma dynamics and to characterize the contribution of ions of planetary origin such as Na+ or K+. MSA consists of a spherical top-hat for energy per charge analysis, followed by a polarized Time-Of-Flight chamber for mass per charge discrimination. The "reflectron" design adopted in this TOF chamber leads to isochronous times of flight ; hence, an enhanced mass resolution (above 50) of the measured ions.


Principal Investigator
Dominique Delcourt (LPP, France)
Lina Z. Hadid (LPP, France)
Yoshifumi Saito (ISAS, Japan)
Shoichiro Yokota (University of Osaka, Japan)
Markus Fraenz (MPS, Germany)
Norbert Krupp (MPS, Germany)
Harald Krueger (MPS, Germany)
Björn Fiethe (IDA, Germany)
Dominique Fontaine (LPP, France)
Sae Aizawa (LPP, France)
Support Engineers
Bruno Katra (LPP, France)
Yvon Alata (LPP, France)
Frederic Leblanc (LPP, France)
Jean-Denis Techer (LPP, France)
Christophe Verdeil (IRAP, France)
Henning Fischer (MPS, Germany)
Hamamatsu Photonics, K. K. (Japan)
MEISEI Electric Co., Ltd. (Japan)
YS DESIGN Ltd. (Japan)
Delta Precis (France)
Plessis Mecanique Precision (France)

Instrument Specifications

Field of view 5 deg × 260 deg
Angular resolution 5 deg × 11.25 deg
Energy range 1 eV/q–38 keV/q
Energy resolution ΔE/E = 8%
k-factor 6.85
Mass range 1–60 amu
Mass resolution m/Δm>40 (<13 keV/q)
m/Δm = 10 (>13 keV/q)
Time resolution 3D distribution function in 4 s (32 energy steps)
3D distribution function in 8 s (64 energy steps)
Geometrical factor (21 windows) High G-factor mode (5.625∘:SW 22.5∘:MI): 7×10−3 cm2sreV/eV (ST)
5×10−4 cm2sreV/eV (LEF)
Mass 4.46 kg
Power 9.1 W
Dimensions 325 mm × 287 mm × 232 mm
Data rate 0.15 kbits/s (L-mode)
1.4 kbits/s (M-mode)
25 kbits/s (H-mode)
after factor 10 compression