2019 URSI Asia-Pacific Radio Science Conference (AP-RASC) | 2019
Development of vacuum, optical and electronic sub-systems for the 2nd generation Cesium fountain frequency standard at NPLI
Abstract
The transition frequency between two hyperfine levels (i.e. $\\vert \\mathrm{F}=4\\vert$ mf $=0$ and $\\vert \\mathrm{F}=3\\vert$ mf $=0)$ of natural Cs-133 atoms is used to define SI second. This definition of SI second is realized in practice using Cs atomic fountain primary frequency standard (PFS). At CSIR-NPL (NPLI), India’s first ever Cesium fountain primary frequency standard, NPLI-CsF1 was indigenously developed, evaluated, successfully compared with fountains from Germany, Russia and China, approved as PFS by CCTF (consultative committee on time and frequency) and contributed to international atomic time (TAI) for few months [1–3]. However, due to some inherent design issues, the fractional frequency uncertainty of the fountain could not be improved beyond $2.5 \\mathrm{x}10^{-15}$. With the motivation to have better and stable fountain with improvised design features, a second-generation Cs fountain is currently under development at NPLI.