AVS 53rd International Symposium
    Vacuum Technology Tuesday Sessions
       Session VT-TuM

Paper VT-TuM1
Turbo Pump Developments for Radioactive Environment in High Energy Physics Applications

Tuesday, November 14, 2006, 8:00 am, Room 2000

Session: Vacuum Generation and Measurement
Presenter: D. Baratto, Varian Inc. VTT, Italy
Authors: D. Baratto, Varian Inc. VTT, Italy
M. Audi, Varian Inc. VTT, Italy
Correspondent: Click to Email
This paper presents a novel development of a new 2000 l/s turbo-molecular pump that is resistent to radioactive environments such as those found in High Energy Physics applications including Tokamaks. A previous prototype has been successfully tested on the JET Tokamak UK. In order to withstand the severe application at JET, the new pump is designed with tritium flow compatibility, resistance to radiation, magnetic and high voltage environments. The new pump has several advantages for these applications over standard configured turbo-molecular pumps that cannot withstand radioactive environments. The pump has been designed with radiation resistance up to 10E+8rad, compatibility with high magnetic fields, and a 10E-9mbarl/s range leak specification that restricts the flow of radioactive gas out of the pump. The pump has an active breaking system that stops the pump without an external venting port in a shorter time than natural deceleration. The pump is equipped with a separate control and drive electronics unit that can be rack mounted behind the biological shield, outside of the radioative area in which the pump is mounted. The controller has galvanic isolation that allows it to operate at high potential. Materials selection was a significant challenge during the design phase of the new pump. Ceramic bearings of the pump permanently lubricated with radiation resistant polyphenyl-ester grease are a specific feature of compatibility with a magnetic device operating in a radioactive environment. Further radiation compatibility was achieved by replacing all elastomeric o-rings with full metal sealing. PEEK sheathed cables and glass ceramic connectors have been used: these materials are radiation resistant, non-magnetic and UHV compatible in terms of leak rate. The performances of the pump are presented. The pump proves to be an effective solution for many high-energy experiments and applications as nuclear fusion, particle acceleretors and synchrotron light sources.