A cooling system (10) for thermal analysis equipment provides rapid cool down and steady state operation of a differential scanning calorimeter (DSC) at any predetermined temperature between a minimal temperature and room temperature using a throttle-cycle cooler based on a single stage compressor (28). The cooling system operates with a mixed refrigerant that includes some liquid fraction at the inlet to a cryostat that houses the key cold elements for the cooling system. A temperature actuated automatic throttle valve (34) in the cooling system increase refrigerant mass flow rate when the DSC increases the heat load (and vice-versa) that is generally provided by a heater. At the same time, the valve design provides a high mass flow during cool down and automatic flow rate reduction at an intermediate temperature as the overall system approaches an operating condition during cool down.