Fig. 1. Structure of an RFQ and the framework of the measurement(a) Transverse section of an RFQ and the electromagnetic field on it, (b) Longitudinal section of an RFQ, (c) Framework of measuring an RFQ

Fig. 2. Flowchart of the tuning algorithm based on response matrix and least squares method

Fig. 3. 3-D model of the RFQ and its field distribution in simulation(a) Model of the RFQ, (b) Transverse section of the RFQ and the place where the field was picked, (c) Dipole and quadrupole components of the RFQ

Fig. 4. Solution with the different weight for dipole components under single tuners' perturbation

Fig. 5. Result comparisons of the tuning experiment in simulation(a) Quadrupole and dipole component errors with different weights, (b) Quadrupole field variation during the tuning, (c) Dipole field variation during the tuning

Fig. 6. Comparison of the quadrupole and dipole component errors with different tuning methods

Fig. 7. Testbed of the RFQ prototype and the experimental results(a) Prototype of the 714-MHz RFQ, (b) Testbed of the prototype, (c) User interface of the motor control and RF measurement, (d) Initial field of the RFQ prototype, (e) Variation of quadrupole and dipole component errors during the tuning