"前级泵" can be translated as "fore-pump" or "backing pump" in English, depending on the specific context and application within the field of vacuum technology or pumping systems.
"Fore-pump" typically refers to a pump that operates at a lower vacuum level and is used to pre-evacuate a system before a higher vacuum pump (such as a diffusion pump or a turbomolecular pump) is engaged.
"Backing pump" is another term used to describe a pump that supports a higher vacuum pump by maintaining a certain vacuum level in the system, often when the higher vacuum pump cannot operate directly at atmospheric pressure.
In many cases, these two terms can be used interchangeably, but the exact choice may depend on the specific terminology used in a particular industry or application.