Miniature atomic scalar magnetometer for space based on the rubidium isotope ⁸⁷Rb

Abstract

A miniature atomic scalar magnetometer based on the rubidium isotope 87 Rb was developed for operation in space. The instrument design implements both M x and M z mode operation and leverages a novel microelectromechanical system (MEMS) fabricated vapor cell and a custom silicon‐on‐sapphire (SOS) complementary metal‐oxide‐semiconductor (CMOS) integrated circuit. The vapor cell has a volume of only 1 mm 3 so that it can be efficiently heated to its operating temperature by a specially designed, low‐magnetic‐field‐generating resistive heater implemented in multiple metal layers of the transparent sapphire substrate of the SOS‐CMOS chips. The SOS‐CMOS chip also hosts the Helmholtz coil and associated circuitry to stimulate the magnetically sensitive atomic resonance and temperature sensors. The prototype instrument has a total mass of fewer than 500 g and uses less than 1 W of power, while maintaining a sensitivity of 15 pT/√Hz at 1 Hz, comparable to present state‐of‐the‐art absolute magnetometers.

Chip-scale atomic devices

“…Chip-scale atomic magnetometers are also under development for applications in space, 243,244 primarily for planetary science missions. These instruments are based on Mx or Mz mode detection and incorporate a novel Silicon-on-Sapphire (SOS) CMOS heater chip.…”

MEMS Components for NMR Atomic Sensors

“…The component u will rotate in phase with B 1 , while v will rotate in quadrature with B 1 . Derivation of equations (4), (5) and (6) can be found in [28]. If we set the oscillating field frequency exactly at the Larmor frequency, then the rotational rate ω R can be extracted from either the absorption mode (v) or the dispersion mode (u).…”

“…For example, in table-top setups, an atomic magnetometer can measure magnetic fields with a sensitivity of 1 f T/ √ H z [3], and an atomic gyroscope can measure rotation with an Angle Random Walk (ARW) of 0.002 deg/ √ hr [4]. The emerging applications that demand low-cost chip-scale atomic sensors [5], [6] have started a trend in the early 2000s on miniaturization of atomic sensors and their components. The advancements in miniaturized cell fabrication [7]- [10], and Vertical Cavity Surface Emitting Lasers (VCSELs) [11], encouraged developments towards miniaturization of atomic clocks [12], atomic magnetometers (NMRMs) [13]- [15], and atomic gyroscopes (NMRGs) [15]- [17].…”

Performance analysis of an optically pumped magnetometer in Earth’s magnetic field

“…Because the energy shift by the Zeeman interaction is based on the scalar product of the measured external magnetic field B 0 and the magnetic moment of the atom, such a magnetometer measures the absolute value of the field. This fact makes them interesting for the realization of absolute field sensors [2][3][4].…”