Optimal design and validation of atom trapping and atomic storage time for active hydrogen maser

From microwave atomic clocks to light clocks, atomic or ionic clocks often rely on atom or ion trapping or manipulation technology. Trapping hydrogen (H) atoms in atomic storage bulbs (ASBs) is one of the key technologies of H atomic clocks. H atoms remain in an ASB for some time during which they undergo several relaxation processes (including spin-exchange collision relaxation, atom-wall collision relaxation, and magnetic-field inhomogeneity relaxation) and interact with the electromagnetic field within the resonant cavity in the TE₀₁₁ mode, giving rise to continuous atomic transitions and self-oscillations. In this study, an optimal atomic storage time T_b for a H maser was determined by optimizing various collisional relaxation times of the atomic ensemble and reducing the width of the atomic resonance line through the continuously adjustable length and radius of the opening of an ASB at various atomic beam intensities ξ (which is the number of atoms in the atomic beam), namely, 3 × 10¹² atoms/s, 4 × 10¹² atoms/s, and 5 × 10¹² atoms/s, while keeping the structural properties and physical conditions of the H maser unchanged. For ξ = 5 × 10¹² atoms/s and T_b ≈ 0.8 s, a frequency stability of 0.95 × 10^-15 could be achieved at 1000 s.