Research On Pulse Double - Line Magnetic Axis Measurement Technology

Abstract:Solenoid is the foundation to construct a beam line of LIA, In order to design and construct a high quality beam line, we should pursue solenoid with ultra-low magnet axis tilt error. The improving performance of solenoid calls for precise magnet axis measurement technique. Pulsed taut-wire technique was widely used for its simple structure, convenient operation and high accuracy.Conventional Pulsed taut-wire technique has only one wire, which measures the background signal and the general signal including magnet axis tilt information at different times. The pure tilt signal can be acquired from their subtraction. This would lead to a rather large uncertainty because the background signal is not constant through different times for the influence of airflow, noise, ground vibration and geomagnetic field fluctuation. To cover this inherent shortage of pulsed taut-wire technique, another wire was brought in to measure the background signal synchronously.A taut wire vibration model is established in pulsed taut-wire technique. Wire’s vibration is simulated analyzed, and the waveforms are calculated when measuring solenoids with tilt and offset. The simulated result is used to design the signal processing circuit that would transfer signals undistorted. The effects of wires’ interaction, solenoid’s leakage magnetic field and wire sag are analyzed, leading to the relation between measured signal and magnetic field distribution and wire sag equation. It finally shows that the signals called by interaction of wires and the leakage magnetic field of solenoid can be treated as constant, which not affect measuring accuracy.The error led by wire sag is estimated from the wire sag equation.A systematic study of Double pulsed taut-wire technique is shown in this paper, problems encountered in constructing experiment platform and their solutions are expounded in detail. Signals called by interaction of wires and the leakage magnetic field of solenoid are measured and quantified experimentally, wire sag equation was proved from actual experiment and new methods to align the wire are proposed. The result of measurement shows that double wire technique decreases the uncertainty of measurement and improves environmental suitability of the system. The resolution of tilt is better than O.1mrad, measuring error is less than 0.1107mrad, and a big part of the error is caused by laser tracker.In the end, we analyze the remaining disadvantage of double wire technique, and propose some advices.