INTECIN   20395
INSTITUTO DE TECNOLOGIAS Y CIENCIAS DE LA INGENIERIA "HILARIO FERNANDEZ LONG"
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Low-cost vacuum baffle based on thermoelectric cooling
Autor/es:
JM SILVEYRA; JM CONDE GARRIDO
Lugar:
Aberdeen
Reunión:
Congreso; 1st International Symposium on Mechanics; 2018
Resumen:
Many modern technologicalprocesses require clean high vacuum environments. Diffusion pumps (coupled withmechanical pumps) can achieve high vacuum pressures (3×10-8 mbar)and are relatively inexpensive and easy to maintain. Their greatest drawback isthe backstreaming of oil vapors that could potentially contaminate the chamberwhere the process of interest is taking place.Likewise, some of theseprocesses produce, as byproduct, contaminants that must be kept from enteringinto the vacuum system: the pipes and, especially, the pumps. One example isthe pulsed laser deposition of thin films of alloys containing elements withhigh vapor pressure, such as sulfur, selenium, or tellurium. These contaminantstravel down the vacuum pipes and may not only be hazardous to the operator´shealth but could also degrade the properties of the oils used in the pumps.We propose a new baffletechnology that overcomes the disadvantages associated with liquid nitrogen orcompressor cooling systems. Our baffle is aimed at trapping both oil vaporsgoing up the vacuum pipes (in the direction of the process chamber) andchalcogenide contaminant vapors (i.e. sulfur, selenium, or tellurium) goingdown the vacuum pipes (in the direction of the diffusion pump), while avoidingthe undesirable partial cryopumping of water. This application does not requiretemperatures in the range of liquid nitrogen, but in the -50 °C to -30 °C range.We developed a virtualprototype of a low-cost baffle for vacuum systems that is cooled down withthermoelectric coolers (TECs). Compared to compressor cooling systems, TECshave useful advantages for this application: they are compact, silent,vibration-free, almost maintenance-free, inexpensive, widely commerciallyavailable, and capable of providing a precise temperature control. The baffleis partly built inside a tee vacuum fitting. A refrigerated cooper helixprovides the trapping surfaces for contaminants flowing between the processchamber and the vacuum pumps. The cost of the baffle is below USD 250. Theproof-of-concept model, implemented by the finite element method, showed that,when using TEC1-12706 modules, the helix can reach temperatures as low as -50ºC. This temperature is more than enough for trapping the contaminants describedabove.