First Prototype of a Low-Cost Vacuum Baffle With Electrical Feedthrough

Abstract

n a previous work, Conde Garrido and Silveyra proposed a novel cold trap (baffle) technology capable of trapping contaminants in vacuum systems. The baffle was designed to be applied in systems to synthesize chalcogenide glass thin films by pulsed laser deposition. While traditional baffles are cooled down with compression cooling systems or cooling solutions such as liquid nitrogen, the reported baffle is cooled down by the thermoelectric effect, which allows for reducing the capital investment, operating costs, as well as start-up and maintenance times. This paper presents the construction, tuning, and characterization of the first physical prototype of the baffle. The characterization included, first, the control of the final pressure reached by the device. To characterize the thermal performance of the baffle, a temperature measurement system was designed and manufactured. Within this measurement system, we highlight a low-cost electric vacuum feedthrough. The results indicate that the constructed baffle can reach pressures lower than 2×10−5mbar, while the cold surfaces reach temperatures of approximately−12◦C. The vacuum and cold temperature levels meet the required conditions for the pulsed laser deposition of chalcogenide glass thin films. However, temperatures are not as low as those estimatedfor the virtual prototype (down to−50◦C). Thermal bridges and resistances present in the fabricated device, neglected in the model, were then identified, pointing out opportunities for improvement. Finally, revisions to the current design are proposed that simplify its manufacturing process, improve its robustness and efficiency, and facilitate its operation and maintenance.