Increasing output current stability of power supply with component replacement

Quadrupole magnets of storage ring must be served with power supplies (quadrupole power supplies) with +/-100 ppm long-term output current stability in Synchrotron Radiation Research Center (SRRC). Using power supplies with lower long-term output current stability could save money but need another control loop to increase their performance that will increase the complexity of circuitry of quadrupole power supply. Without adding another control loop, some components of quadrupole power supply are replaced by ones with more precious and insensitive to temperature variation; so that the same circuitry structure of quadrupole power supply is kept without increasing its complexity and could reach +/-25 ppm long-term output current stability.