A NEW SAMPLE CHAMBER WITH TEMPERATURE AND HUMIDITY CONTROL FOR LIPID AND FIBER S

点击翻译按钮获取中文摘要

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. A new sample chamber has been designed and built to accurately control the relative air humidity and temperature environment of the sample during the x-ray measurement. The design is based on Peltier elements in a feed-back loop with Proportional Integral Differential (PID) control electronics for each of the control parameters. This allows for quickly changing and reliably controlling the temperature and humidity conditions inside the sealed chamber. Initial commissioning and characterization of the chamber showed that the control mechanism was working as anticipated, but it took longer than expected to optimize the PID parameters for the three independent control loops. Furthermore, the tests revealed that the sample temperature inside the chamber reached an equilibrium rather slowly and showed a tendency to oscillate due to inefficient heat exchange of the Peltier element responsible for the sample temperature control. Thus, a new water cooled mounting plate was designed and fitted to the chamber, which considerably improved the temperature stability and settling time for the sample temperature. The chamber has already successfully been used for lipid-protein interaction studies at the beamline, and efforts are continued to further optimize the stability and accuracy of the control. The control electronics is accessible by a PC through a serial port (RS232) and all the control parameters can be set remotely. We are planning to integrate the chamber control into the DCS/Blu-Ice beam line software.