2007/06/29 by L. Carbone, A. Cavalleri, G. Ciani +6 · 1 citation
Earth and Planetary Sciences · Physics and Astronomy · #Geophysics and Gravity Measurements #Pulsars and Gravitational Waves Research #Superconducting and THz Device Technology #gr-qc
paper · pdf · doi:10.1103/physrevd.76.102003
published as Phys.Rev.D76:102003,2007 · 21 pages, 16 figures, submitted to Physical Review D
arxiv created 2007/06/29 · openalex publication_date 2007/11/16 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
The low frequency sensitivity of space-borne gravitational wave observatories will depend critically on the geodesic purity of the trajectories of orbiting test masses. Fluctuations in the temperature difference across the enclosure surrounding the free-falling test mass can produce noisy forces through several processes, including the radiometric effect, radiation pressure, and outgassing. We present here a detailed experimental investigation of thermal gradient-induced forces for the Laser Interferometer Space Antenna (LISA) gravitational wave mission and the LISA Pathfinder, employing high resolution torsion pendulum measurements of the torque on a LISA-like test mass suspended inside a prototype of the LISA gravitational reference sensor that will surround the test mass in orbit. The measurement campaign, accompanied by numerical simulations of the radiometric and radiation pressure effects, allows a more accurate and representative characterization of thermal-gradient forces in the specific geometry and environment relevant to LISA free-fall. The pressure dependence of the measured torques allows clear identification of the radiometric effect, in quantitative agreement with the model developed. In the limit of zero gas pressure, the measurements are most likely dominated by outgassing, but at a low level that does not threaten the current LISA noise estimate, which assumes a maximum net force per degree of temperature difference of 100(pN)/(K) for the overall thermal gradient-induced effects.