Accurate determination of the magnetic axis of a solenoid using measured field data and understanding the beam dynamics

Abstract Fundamental understanding of both the theory and the measurement procedure of a solenoid is the key to execute the project cost effectively and to achieve the desired performance. Attempt is made to understand the beam dynamic of charge particles by considering the conservation of canonical angular momentum of non-zero values. Analytical expression to generate a parallel beam using solenoid is derived. Effect of final beam size on the values of spherical aberration coefficient and focal length of a solenoid is studied using electron trajectories. Practical procedure to tune the above two parameters of a solenoid by simple modification is demonstrated. Mathematical model is derived to accurately determine the axis of a solenoid and the magnetic centre using measured magnetic field data and experimentally demonstrated the validity of the theory. Several solenoids are characterised using the procedure and used in the 9.5 MeV 10 kW electron LINAC which is appropriate for the use of sterilization of medical products and food irradiation.