The engineering design of NB snubber

Abstract

Snubber with transformer core configuration is often used as functional passive protection device to be inserted between the ion source and its acceleration power supply for arc quenching purpose where bias power supplier is implemented to maximize flux swing while vacuum sparking. Fink, Baker and Owren developed related design method by neglecting the inductance effects of the core snubber transformer and assuming that the snubber core never saturates, which gives the analysis solution to the design of core snubber. The Fink-Baker method used the assumption that the eddy current resistance is about 2.5 times its logic derived one which is an empirical design method and verified in their snubber tests in Lawrence Berkeley National Laboratory. This method is further used in the design of DIIID 100 kV snubber. By eliminating the assumption of 2.5 times empirical factor of Fink- Baker method, a logic safe design is developed for more compact snubber. Due to that the inductance does exist in the equivalent circuit of the core snubber and the design is the essence of engineering, its effects and its design rules are discussed further by introducing engineering factor to account for the neglected parallel inductance effects. Some simulations and experimental evaluations have been done to verify the analysis results, which could be used for detail engineering design of core snubbers as well as common transformers. By considering the time-varying resistance effects in the common transformer model, its starting effects can be recognized more clearly.