Simulation and Experiment of Multi-section Coil for C Field Used in Passive Hydrogen Maser

Passive hydrogen maser (PHM) has the advantages of high frequency stability and low frequency drift. It has been widely used in the navigation system and frequency calibration. Atomic transition signal amplitude of PHM directly determines the system signal to noise ratio, and thus affect system performance, which makes it one of the most important parameters of PHM. Straight solenoid is widely used in PHM to produce the C field for atomic transition. Due to restriction of structural of the physical package, there is improvement potential for homogeneity of magnetic field. This paper discusses the feasibility of multi-section coil for the C field of PHM. Simulation and optimization of the parameters of the multi-section coil is carried out, including length, number of sections, turns, spacing and diameter. Design of multi-section coil with better homogeneity of the C field can be given by the simulation software. Inhomogeneity of about 2% of the C field is realized comparing to about 10% of the straight solenoid. According to the simulation results, several multi-section coils are manufactured. Application and test of these multi-section coils in physical package of hydrogen maser are carried out. Experimental results show that atomic transition signal gain can be increased by about 10%, which is beneficial to the performance of PHM.