Controller for a linear accelerator

In an rf resonator having an rf power supply, a method of controlling a phase shift between a reference signal and a measured signal comprising the steps of:

• (a) providing a reference sinusoidal signal having a reference phase;
• (b) generating a transduced signal from the rf resonator, the transduced signal having a pick-up phase;
• (c) shifting the phase of the reference sinusoidal signal by 90° relative to the reference phase, so as to generate a reference cosinusoidal signal;
• (d) generating a first phase demand signal representing the sine of a desired angle of phase shift of the said reference sinusoidal signal;
• (e) generating a second phase demand signal representing the cosine of a desired angle of phase shift of the said reference sinusoidal signal;
• (f) multiplying the said cosinusoidal reference signal with the first phase demand signal to generate a first composite signal;
• (g) multiplying the said sinusoidal reference signal with the second phase demand signal to generate a second composite signal;
• (h) summing the first and second composite signals to generate a phase shifted output signal which is a second sinusoidal signal that is shifted in phase relative to the reference phase of the reference sinusoidal signal by the said desired angle of phase shift;
• (i) shifting the phase of the second sinusoidal signal by 90° so as to generate a second cosinusoidal signal whose phase is shifted relative to the reference cosinusoidal signal by the said desired angle of phase shift;
• (j) multiplying the transduced signal with the second cosinusoidal signal so as to generate a phase error signal having a dc component from the resultant product;
• and
• (k) generating a control signal on the basis of the dc component of the phase error signal, to control the output of the said rf power supply so as to minimize the phase error signal.

In an rf resonator having an rf power supply, a method of controlling a phase shift between a reference signal and a measured signal comprising the steps of:

• (a) providing a reference sinusoidal signal having a reference phase;
• (b) generating a transduced signal from the rf resonator, the transduced signal having a pick-up phase;
• (c) shifting the phase of the reference sinusoidal signal by 90° relative to the reference phase, so as to generate a reference cosinusoidal signal;
• (d) generating a first phase demand signal representing the sine of a desired angle of phase shift of the said reference sinusoidal signal;
• (e) generating a second phase demand signal representing the cosine of a desired angle of phase shift of the said reference sinusoidal signal;
• (f) multiplying the said cosinusoidal reference signal with the second phase demand signal to generate a first composite signal;
• (g) multiplying the said sinusoidal reference signal with the first phase demand signal to generate a second composite signal;
• (h) generating a phase shifted output signal which is a second cosinusoidal signal, by determining the difference between the said first and second composite signals, the said second cosinusoidal signal being shifted in phase relative to the reference phase of the reference cosinusoidal signal by the said desired angle of phase shift;
• (i) multiplying the transduced signal with the second cosinusoidal signal so as to generate a phase error signal having a dc component from the resultant product;
• and
• (j) generating a control signal on the basis of the dc component of the phase error signal, to control the output of the said rf power supply so as to minimize the phase error signal.

A phase shifter apparatus for generating a phase shift in a sinusoidal signal, comprising:

• an oscillator for generating a first sinusoidal signal having a reference phase;
• a quadrature signal generator arranged to shift the phase of the said sinusoidal signal by 90° relative to the said reference phase so as to generate a first cosinusoidal signal;
• a desired phase shift signal generator arranged to generate a first phase signal representing the sine of a desired angle of phase shift of the said first sinusoidal signal, and a second phase signal representing the cosine of the said desired angle of phase shift;
• a first multiplier arranged to multiply the said cosinusoidal signal with the first phase signal representing the sine of the said desired angle of phase shift, to generate a first composite signal, and a second multiplier to multiply the said sinusoidal signal with the second phase signal representative of the cosine of the said desired angle of phase shift, to generate a second composite signal;
• and
• a summer arranged to sum the first and second composite signals to generate a phase shifter output signal which is a second sinusoidal signal that is shifted in phase relative to the reference phase of the first sinusoidal signal by the said desired angle of phase shift.

A method of generating a phase shift in a sinusoidal signal, comprising the steps of:

• (a) generating a first sinusoidal signal having a reference phase;
• (b) shifting the phase of the said sinusoidal signal by 90° relative to the said reference phase so as to generate a first cosinusoidal signal;
• (c) generating a first phase signal representing the sine of a desired angle of phase shift of the said first sinusoidal signal, and a second phase signal representing the cosine of the said desired angle of phase shift;
• (d) multiplying the said cosinusoidal signal with the first phase signal representing the sine of the said desired angle of phase shift, to generate a first composite signal, and multiplying the said sinusoidal signal with the second phase signal representative of the cosine of the said desired angle of phase shift, to generate a second composite signal;
• and
• (e) summing the first and second composite signals to generate a phase shifter output signal which is a second sinusoidal signal that is shifted in phase relative to the reference phase of the first sinusoidal signal by the said desired angle of phase shift.