| AVS 66th International Symposium & Exhibition | |
| Vacuum Technology Division | Tuesday Sessions |
| Session VT-TuA |
| Session: | Advanced Applications of Vacuum Technology |
| Presenter: | Junichiro Kamiya, Japan Atomic Energy Agency, Japan |
| Authors: | J. Kamiya, Japan Atomic Energy Agency, Japan M. Kinsho, Japan Atomic Energy Agency, Japan N. Ogiwara, KEK, Japan M. Sakurai, Osaka Vacuum, Ltd., Japan T. Mabuchi, Osaka Vacuum, Ltd., Japan K. Wada, Tokyo Electronics Co., Ltd., Japan |
| Correspondent: | Click to Email |
Challenges for achieving an ultrahigh vacuum (UHV) region in J-PARC 3 GeV rapid cycling synchrotron (RCS), which produces proton beam with 1 MW power, come from the large static and dynamic outgassing. In the RCS vacuum system, turbomolecular pumps (TMP) have been used as main pump because it can evacuate such continuous and additional outgassing with a large pumping speed in the wide pressure range. TMP also has the advantage of not causing pressure instabilities like ion pumps. The more than 10 years operation of the RCS vacuum system showed that the UHV was rapidly obtained from the atmospheric pressure. It was also shown that the large additional outgassing during the high-power beam operation was promptly evacuated by the TMP due to its constant pumping speed in the wide pressure rage. The future operation with more high-beam power requires the vacuum system for the lower pressure region. The pumping speed and compression ratio of the standard TMP is limited by the rotational speed of the rotor. We have developed a TMP with the rotor of titanium alloy, which have much higher mechanical strength than aluminum alloy for the normal rotter. When the rotational speed increase by a factor of 1.3, the pumping speed and compression ratio increase by a factor of 1.3 and 12.5, respectively. The increase of the compression ratio is especially effective for hydrogen, which is the main outgas component in the UHV region. Challenges in the development comes from the difficulty of the machining performance and the weightiness of the titanium alloy comparing with the aluminum alloy. We report the signification and the status of the development of the TMP with titanium alloy.