Method and system for determining a suppression factor of a suppression system and a lithographic apparatus

A system comprising a first system and a suppression system arranged to suppress migration of a contaminant gas out of the first system, the suppression system having a suppression factor being an indication of the performance of the suppression system, the system further comprising:

• a tracer gas supply configured to introduce a tracer gas in the first system;
• a detector system configured to detect an amount of the tracer gas that has migrated out of the first system;
• and
• a control unit configured to determine a first suppression factor for the suppression system for the tracer gas and to determine a second suppression factor for the suppression system for the contaminant gas based on the first suppression factor,
• wherein the second suppression factor, Scont, is computed from the first suppression factor, Stracer, by:
• Scont=Stracer(Dtracer/Dcont)
• where Dtracer is the diffusion coefficient of the tracer gas and Dcont is the diffusion coefficient of the contaminant gas.

A lithographic apparatus comprising:

• a first system and a suppression system arranged to suppress migration of a contaminant gas out of the first system, the suppression system having a suppression factor being an indication of the performance of the suppression system;
• a tracer gas supply configured to introduce a tracer gas in the first system;
• a detector system configured to detect an amount of the tracer gas that has migrated out of the first system;
• and
• a control unit configured to determine a first suppression factor for the suppression system for the tracer gas and to determine a second suppression factor for the suppression system for the contaminant gas based on the first suppression factor, wherein the second suppression factor Scont, is computed from the first suppression factor, Stracer, by:
• Scont=Stracer(Dtracer/Dcont)
• where Dtracer is the diffusion coefficient of the tracer gas and Dcont is the diffusion coefficient of the contaminant gas;
• wherein the suppression system is provided to prevent migration of the contaminant gas to a second system of the lithographic apparatus.

A non-transitory computer-readable medium having machine executable instructions, the instructions being executable by a machine to perform a method for determining a suppression factor of a suppression system, the suppression system arranged to suppress migration of a contaminant gas out of a first system, the suppression factor being an indication of the performance of the suppression system, the method comprising:

• introducing a tracer gas in the first system;
• detecting an amount of the tracer gas that has migrated out of the first system;
• determining a first suppression factor for the suppression system for the tracer gas;
• and
• determining a second suppression factor for the suppression system for the contaminant gas based on the first suppression factor,
• wherein the second suppression factor, Scont, is computed from the first suppression factor, Stracer, by:
• Scont=Stracer(Dtracer/Dcont)
• where Dtracer is the diffusion coefficient of the tracer gas and Dcont is the diffusion coefficient of the contaminant gas.