Thermal conditioning method

A lithographic apparatus, comprising:

• a patterning system configured to transfer a pattern onto a substrate;
• and
• a physical object comprising:
• a cooling duct provided in the physical object, the cooling duct extending from a supply side of the physical object configured to receive a two-phase cooling medium into the cooling duct, to a discharging side of the same physical object configured to discharge the two-phase cooling medium from the cooling duct,
• the cooling duct comprising a pre-heating duct, a phase transitioning duct and a discharging duct,
• the pre-heating duct configured to guide the two-phase cooling medium in a liquid phase from the supply side at least partly towards the discharging side, the pre-heating duct configured to pre-heat the two-phase cooling medium and the pre-heating duct absorbing heat from the same physical object,
• the phrase transitioning duct configured to guide the two-phase cooling medium from the pre-heating duct to the discharging duct, the phase transitioning duct extending from the supply side to the discharging side, the phase transitioning duct configured such that the two-phase cooling medium at least partly transitions from the liquid phase towards a gas phase in the transitioning duct in the same physical object, and
• the discharging duct configured to guide the two-phase cooling medium to a discharge at the discharging side,
• wherein the two-phase cooling medium exhibits an increased heat absorption in a transition range of gas to liquid ratios during the transition from being substantially in liquid phase to being substantially in gas phase, the increased heat absorption being in respect to the heat absorption of the two-phase cooling medium in the liquid phase and gas phase respectively, wherein the cooling duct comprising the two-phase cooling medium provides a gas to liquid ratio of the two-phase cooling medium in the pre-heating duct below the transition range, provides the gas to liquid ratio of the two-phase cooling medium in the transitioning duct in the transition range, and provides the gas to liquid ratio of the two-phase cooling medium in the discharging duct above the transition range.