Speaker
Description
A compact superconducting synchrotron for heavy-ion therapy is under construction at National Institutes for Quantum Science and Technology. This synchrotron is being downsized for widespread applicability in medical facilities using combined-function superconducting magnets for 90-degree main dipoles. The magnetic field of the dipole reaches 3.5 T with a field gradient of 1.5 T/m by quadrupole. The dipole field strength must be measured within accuracy of less than 250 ppm over the field region of ±30 mm in horizontal and ±19 mm in vertical.
Such accuracy is generally achieved with rotating coils, however, no such measurement system have been made with an long magnet with a small bending radius as in this case, necessitating a careful study (about 3m in length and 1.89m bending radius).
At present, we are developing a compact measurement system to be attached to the end of an industrial robotic arm, allowing the measurement of the local magnetic field distribution at arbitrary positions along the beam trajectory. The system includes a coil with a length of 75 mm and a radius of 15 mm approximately, as well as encoders, piezo motors, accelerometers for field direction measurements and other parts. Consequently, the overall length and diameter of the system are expected to be around 250 mm and 35 mm.
In this presentation, we report the design and current status of this system.
