# US 10,374,551 B2 · Subcritical-voltage magnetron RF power source

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- Number: US 10,374,551 B2
- Document ID: US10374551B2
- Status: Granted
- Kind: B2
- Application number: 15/430,497
- Filed: 2017-02-12
- Published: 2017-08-31
- Granted: 2019-08-06
- Earliest claimed: 2016-02-12
- Assignees: Muons, Inc.
- Applicants: Muons, Inc.
- Inventors: Grigory M. Kazakevich; Michael L. Neubauer; Valeri A. Lebedev; Vyacheslav P. Yakovlev
- Web page: https://patentgrep.com/patent/US10374551B2

## CPC

- H03B 9/10: using a magnetron
- H05H 7/02: Circuits or systems for supplying or feeding radio-frequency energy
- H05H 2007/025: {Radiofrequency systems}
- H03B: GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS (generators adapted for electrophonic musical instruments G10H; masers or lasers H01S; generation of oscillations in plasma H05H)
- H05H: PLASMA TECHNIQUE (apparatus or processes specially adapted for producing X-rays H05G2/00); PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS

## Abstract

A system and method of operating a magnetron power source can achieve a broad range of output power control by operating a magnetron with its cathode voltage lower than that needed for free running oscillations (e.g., below the Kapitsa critical voltage or equivalently below the Hartree voltage) A sufficiently strong injection-locking signal enables the output power to be coherently generated and to be controlled over a broad power range by small changes in the cathode voltage. In one embodiment, the present system and method is used for a practical, single, frequency-locked 2-magnetron system design.

## Claims

### Claim 1

A system for powering an accelerating cavity, comprising:
a first power source configured to receive an input injection-locking signal and produce an injection-locked first output signal using the input injection-locking signal;
a second power source coupled to the first power source and configured to receive the injection-locked first output signal and produce a second output signal, the second power source including a high-power magnetron receiving a cathode voltage, the cathode voltage controlling a power of the second output signal; and
a voltage supply system coupled to the second power source and configured to control the power of the second output signal by providing a subcritical feeding voltage as the cathode voltage, the subcritical voltage below a critical voltage needed for self-excitation of the high-power magnetron.

### Claim 2 (depends on 1)

The system of claim 1, wherein the voltage supply system comprises:
a probe configured to measure an accelerating voltage signal in the accelerating cavity; and
a power feedback loop configured to control the power of the second output signal using the measured accelerating voltage signal.

### Claim 3 (depends on 2)

The system of claim 2, wherein the voltage supply system comprises:
a low-power high-voltage (HV) power supply;
a main HV power supply coupled to the low-power HV power supply and configured to be biased by the low-power HV power supply; and
a controller configured to control the low-power HV power supply using the measured accelerating voltage signal.

### Claim 4 (depends on 2)

The system of claim 2, wherein the high-power magnetron is configured to injection-lock a frequency of the high-power magnetron using the received injection-locked first output signal.

### Claim 5 (depends on 1)

The system of claim 1, wherein the first power source comprises a solid state amplifier.

### Claim 6 (depends on 1)

The system of claim 1, wherein the first power source comprises a low-power magnetron configured to be driven and phase-locked by the input injection-locking signal.

### Claim 7 (depends on 6)

The system of claim 6, further comprising a probe configured to measure an accelerating voltage signal in the accelerating cavity, and wherein the low-power magnetron is configured to be phase-locked by phase modulation of the input injection-locking signal using a phase feedback loop comparing a phase of the input injection-locking signal with a phase of the measured accelerating voltage signal.

### Claim 8 (depends on 7)

The system of claim 7, further comprising a phase controller configured to frequency-lock the low-power magnetron.

### Claim 9 (depends on 7)

The system of claim 7, wherein the voltage supply system comprises a power feedback loop configured to control the power of the second output signal using the measured accelerating voltage signal.

### Claim 10 (depends on 9)

The system of claim 9, wherein the voltage supply system comprises:
a low-power high-voltage (HV) power supply;
a main HV power supply coupled to the low-power HV power supply and configured to be biased by the low-power HV power supply; and
a controller configured to control the low-power HV power supply using the measured accelerating voltage.

### Claim 11 (depends on 6)

The system of claim 6, wherein the low-power magnetron and the high-power magnetron are configured to operate in a continuous wave (CW) mode.

### Claim 12 (depends on 6)

The system of claim 6, wherein the low-power magnetron and the high-power magnetron are configured to operate in a pulsed mode.

### Claim 13

A method for operating a magnetron power source, comprising:
driving a first power source using an input injection-locking signal;
producing an injection-locked first output signal by processing the input injection-locking signal using the first power source;
driving a second power source using the injection-locked first output signal, the second power source including a high-power magnetron receiving a cathode voltage;
producing a second output signal using the high-power magnetron, the second output signal having a power being a function of the cathode voltage; and
providing a subcritical feeding voltage as the cathode voltage, the subcritical voltage below a critical voltage needed for self-excitation of the high-power magnetron.

### Claim 14 (depends on 13)

The method of claim 13, wherein driving the first power source using the input injection-locking signal comprises:
driving a low-power magnetron using the input injection-locking signal; and
phase-locking the low-power magnetron using the input injection-locking signal.

### Claim 15 (depends on 13)

The method of claim 13, further comprising powering an accelerating cavity using the second output signal.

### Claim 16 (depends on 15)

The method of claim 15, wherein providing the second output signal comprises:
measuring an accelerating voltage in the accelerating cavity; and
controlling the power of the second output signal using the measured accelerating voltage signal.

### Claim 17 (depends on 16)

The method of claim 16, wherein controlling the power of the second output signal comprises:
biasing main high-voltage (HV) power supply using a low-power HV power supply; and
controlling the low-power HV power supply using the measured accelerating voltage.

### Claim 18 (depends on 17)

The method of claim 17, further comprising injection-locking a frequency of the high-power magnetron using the received injection-locked first output signal.

### Claim 19 (depends on 18)

The method of claim 18, wherein driving the first power source using the input injection-locking signal comprises:
driving a low-power magnetron using the input injection-locking signal; and
phase-locking the low-power magnetron using the input injection-locking signal.

### Claim 20 (depends on 19)

The method of claim 19, wherein phase-locking the low-power magnetron using the input injection-locking signal comprises phase modulating the input injection-locking signal using a phase feedback loop comparing a phase of the input injection-locking signal with a phase of the measured accelerating voltage signal.