Compensating method for feedback coaxial line drift of cavity of HIRFL

A compensating method for the coaxial line drift due to the temperature change using an additional measuring coaxial line is proposed for the low-level radio frequency(RF) control system of Heavy Ion Research Facility in Lanzhou (HIRFL). We measured the temperature effects on the RF phase and RF loss at the SYV50-2-41 cable with and without using the additional measuring coaxial line, respectively. The measured results show that, the long-term phase instability with compensation can be reduced to 1/50 of the one without compensation; the long-term amplitude drift can be reduced to 1/10 at least.