| 摘要 |
PURPOSE:To prevent melting of work pieces by investigating the AC current flowing in a deflecting coil disposed in the irradiating route for an electron beam and making the relation between the joint positions of the work pieces and the position of the electron beam detectable. CONSTITUTION:A titled device consisting of a zero point detecting section 15 for detecting the zero point of the AC current flowing in a polarizing coil 6, a collector 8 for detecting the secondary energy 9 generated by collision of an electron beam 3 and work pieces 4, and an oscilloscope 13. Said coil 6 is disposed in the irradiating route of the beam 3 which is so controlled as to scan across the joint 7 of the work pieces 4. Said oscilloscope 13 compares the point where the detected value of the secondary energy 9 is minimum with the detection signal for zero point from the detection section 15 and detects the position relation of the beam 3 with the joint 7 of the work pieces 4. The melting of the work pieces is prevented by the above-mentioned device. |
