Ion transfer tube flow and pumping system load

A mass spectrometer system comprising:

• an ion source, the ion source configured to produce ions from a sample;
• a vacuum chamber;
• a mass analyzer within the vacuum chamber, the mass analyzer configured to determine mass-to-charge ratios for ions from the sample;
• a first transfer tube between the ion source and the vacuum chamber, the transfer tube configured to allow passage of the ions from the ion source to the vacuum chamber;
• a transfer tube heater configured to heat the transfer tube to and maintain the transfer tube at an operating temperature;
• a vacuum pump configured to maintain the vacuum chamber at a low pressure;
• a computer readable storage medium having program instructions for performing steps of:
• controlling the transfer tube heater to maintain the first transfer tube at the operating temperature and the vacuum pump to maintain the vacuum chamber at an operating pressure;
• reducing the pump speed of the vacuum pump in response to receiving a transfer tube swap instruction;
• lowering the temperature of the first transfer tube to below a first threshold;
• operating the vacuum pump at the reduced pump speed while the first transfer tube is replaced with a second transfer tube to maintain the vacuum chamber at a pressure between atmospheric pressure and the operating pressure;
• heating a second transfer tube to a temperature above a pump down temperature;
• and
• increasing the pump speed of the vacuum pump after the temperature of the second transfer tube exceeds a second threshold to return the mass analyzer to the operating pressure.