Magnetometry with mesospheric sodium（磁力测定与中间层钠）.pdf

Magnetometry with mesospheric sodium a,1 b b c James M. Higbie , Simon M. Rochester , Brian Patton , Ronald Holzlöhner , Domenico Bonaccini Caliac, and Dmitry Budkerb,d a Department of Physics and Astronomy, Bucknell University, Lewisburg, PA 17837; bDepartment of Physics, University of California, Berkeley, CA 94720-7300; c Laser Systems Department, European Southern Observatory, D-85748 Garching near Munich, Germany; and d Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 Edited by William Happer, Princeton University, Princeton, NJ, and approved December 30, 2010 (received for review September 16, 2010) Measurement of magnetic fields on the few 100-km length scale is significant for many geophysical applications including mapping of crustal magnetism and ocean circulation measurements, yet avail- able techniques for such measurements are very expensive or of limited accuracy. We propose a method for remote detection of magnetic fields using the naturally occurring atomic sodium-rich layer in the mesosphere and existing high-power lasers developed for laser guide star applications. The proposed method offers a dramatic reduction in cost and opens the way to large-scale, par- allel magnetic mapping and monitoring for atmospheric science, navigation, and geophysics. atomic physics ∣ geomagnetism ∣ optical pumping easurements of geomagnetic fields are an important tool M for peering into the Earth’s interior, with measurements at differing spatial scales giving information about sources at cor- responding depths. Mapping of fields on the few meter scale can locate buried ferromagnetic objects (e.g., unexploded ordnance or abandoned vessels containing toxic waste), whereas maps of magnetic fields on the kilometer scale are used to locate