| 摘要 |
PROBLEM TO BE SOLVED: To provide a vacuum pump that can restrain a reaction product from accumulating in screw grooves.SOLUTION: A turbo molecular pump comprises a cylindrical part and a stator 32 opposed to a peripheral surface of the cylindrical part, and screw grooves 32a and screw threads 32b are alternately formed in an inner peripheral surface of the stator 32. A pair of groove side walls 321 and 322 that connect bottom surfaces 320 of the screw grooves 32a and top surface 323 of the screw threads 32b are non-vertical walls formed in such a manner that a groove width expands from the side of the bottom surfaces to the side of the top surfaces.SELECTED DRAWING: Figure 3 |
