DynaCool PPMS
Located in Kelly Room xxx (Pallavi Dhagat PI; Phil Lenox grad student). Tate group: Aaron Dethlefs & Okan Agirseven.
Training
The Quantum Design DynaCool is an instrument designed to measure a variety of a sample’s physical properties while controlling the conditions experienced by the sample.
The Quantum Design DynaCool is a next generation Physical Property Measurement System (PPMS). The PPMS DynaCool is a completely redesigned instrument that provides all the capabilities of the PPMS without the need for any liquid cryogens. The system uses a single two-stage pulse tube cooler to cool both the superconducting magnet and the temperature control system, providing a low vibration environment for sample measurements.
The PPMS DynaCool employs a minimum amount of condensed liquid Helium-4 for cooling both the sample chamber and superconducting magnet. As a result, the system requires only a small volume of bottled helium gas for its fully automated startup and operation. The PPMS DynaCool also comes standard with an integrated cryopump used to pump out the sample space to a vacuum of < 10-4 Torr. This makes the PPMS DynaCool compatible with all existing Quantum Design cryogenic hardware, or any other user-designed experiments.
For temperature control, DynaCool uses a novel gas flow regulation system to improve both cooling power and temperature stability as compared to the already state-of-the-art PPMS temperature control. Along with sophisticated control software, this system provides seamless transitions between high temperatures (400 K) with minimal cooling power needs, intermediate temperatures with rapid slewing and large cooling needs, and stable operation near the base temperature (< 1.8 K) with cooling provided by evaporating liquid helium. With this new control system PPMS DynaCool is capable of cooling a standard PPMS sample puck from 300 K to 1.9 K, stable, in less than 40 minutes. The sample chamber design has also been improved for better thermal uniformity at both low and high temperatures while maintaining the robust 12-pin sample puck interface from the original PPMS. Multiple thermometers and heaters manage temperature gradients and ensure smooth temperature control throughout the accessible temperature range.
The PPMS DynaCool comes with a built in cryopump and vacuum gauge for controlling the sample environment. The cryopump can pump out the sample chamber to less than 10-4 Torr in under 10 minutes. This feature is fully integrated allowing you to change the chamber environment during a programmed sequence or script.
The PPMS DynaCool comes equipped with either a 9 T or 14 T conduction cooled superconducting switch-less magnet system. This system includes a hybrid digital/analog magnet controller, designed for precise, quiet control of the magnetic field. The bipolar design also allows smooth continuous ramping through zero field. Magnet control software monitors the temperature of the magnet and cryostat at 3 locations to ensure proper operation of the magnet system and avoid time consuming quenches. The PPMS DynaCool has a built in magnetic shield. For a system with a 9 T magnet, this shield maintains the 5 gauss line <30 cm the surface of the cryostat cabinet allowing the system to be installed closer to other sensitive instruments for better lab space utilization.
