The Welch 1400 is capable of attaining the depth of vacuum required, however, its flow rate is not fast enough....only 0.9cfm at free air. When you are processing, the moment you reach your target temperatures and shut down the bombarder things begin to cool. Any impurities that have not been evacuated from the tube by the time the temperature falls by 100 degrees or so will be reabsorbed into the glass wall. A Welch 1405 is better...at 3.2cfm, but the 1402 with its 5.6cfm rating or an equivalent is a much better choice for conventional neon processing.
Additionally, any pump's overall throughput will be greatly enhanced when paired with a good diffusion pump.
Having said that, if you are oven pumping a small vessel and using an induction heater to convert your electrode shells, the pumping speed is less critical since you can maintain your temperature setpoint indefinetly until your system attains the vacuum level. If someone were trying to oven pump a tiny piece and only had the 1400 available to try, I would say use it for that, but beyond this limited use, the 1400 is not really a good option and really won't be helpful in a conventional bombarding scenario.
