METHOD AND CIRCUIT FOR CONTROLLING QUADRUPOLE MASS ANALYSER

摘要

PROBLEM TO BE SOLVED: To control an analyser so as to obtain uniform resolving power within a wide mass range by directly comparing the peak value of the voltage applied to a quadrupole rod with reference voltage to feed back the same to a high frequency generation circuit. SOLUTION: The peak value U+V of voltage U+Vcoswt (V; peak of high frequency voltage) wherein the high frequency voltage from a high frequency power amplifier 5 and the DC voltage U from a current voltage generation circuit 16 are superposed one upon another is compared with the first reference voltage V0 -U0 from a first reference voltage generation circuit 12. As a result, the voltage generating in an error signal voltage generating resistor 10 is detected to be sent to a differential amplifier 14 through a low frequency amplifier 11. The amplifier 14 compares this signal with the second reference voltage from a second reference voltage generation circuit 15 attenuating the first reference voltage to 1/30 and feeds back the difference to an equilibrium amplifier 3. DC voltage U is generated in the circuit 16 on the basis of reference voltage. Therefore, precisely controlled voltage U±Vcoswt can be applied to the rod of an analyser.