Phase-Lock Loop Synchronization for Synchrocyclotron RF Drive
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Synchrocyclotrons face inefficiencies in ion beam acceleration and extraction due to unsynchronized phase and amplitude of the RF drive with the ion beam, leading to energy loss and decreased average beam current, especially when varying final beam energy, and are limited by the use of iron-containing cyclotrons which alter magnetic field profiles.
Innovation Solution
Implementing phase-lock loop control to synchronize the phase, frequency, and amplitude of the RF drive with the ion beam throughout the acceleration and extraction process, using sensors and electronic control units to monitor and adjust the RF drive in real-time, and employing a non-axisymmetric pulsed magnetic kicker field for precise beam extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the RF frequency is adjusted to match the cyclotron frequency of the ion beam, then the beam acceleration efficiency is improved, but the phase synchronization between RF drive and ion beam orbit deteriorates when the final beam energy is varied
Solution Approach 1:
The patent implements a phase-lock loop that continuously monitors the phase difference between the RF drive and ion beam orbit, and adjusts the RF frequency in real-time to maintain synchronization. This feedback mechanism resolves the contradiction by dynamically adapting the RF frequency to match the changing cyclotron frequency as beam energy varies, thereby maintaining both acceleration efficiency and phase synchronization across different energy levels.
Solution Approach 2:
The system transitions from a static RF frequency adjustment approach to a dynamic phase-lock loop control system that continuously adapts the RF frequency based on the actual phase relationship with the ion beam. This dynamic adjustment ensures optimal acceleration efficiency while maintaining phase synchronization even when final beam energy is varied, resolving the adaptability issue.
2Force
If iron is used to generate and shape the acceleration field, then the magnetic field intensity is improved, but the magnetic field profile changes when coil currents are varied, limiting energy variation flexibility
Solution Approach 1:
The patent employs iron-free cyclotron magnets that allow independent control of magnetic field intensity and field profile through parameter changes in coil currents. By eliminating iron, the system can vary the final beam energy over a wide range (e.g., 0.5-2.5 MeV/u) without the magnetic field profile distorting, thereby resolving the contradiction between achieving sufficient field intensity and maintaining energy variation flexibility.
3Device complexity
If the RF drive phase and amplitude are not synchronized with the ion beam, then the device complexity is reduced, but the beam quality and average beam current deteriorate
Solution Approach 1:
The phase-lock loop provides continuous feedback control of the RF drive phase and amplitude based on the ion beam orbit phase. This feedback mechanism automatically maintains optimal synchronization without requiring complex manual adjustment systems, thereby achieving high beam quality and average current while keeping the control system architecture relatively simple and elegant.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach ensures high extraction efficiency and flexibility in varying final beam energy without energy degraders, maintaining optimal beam quality and reducing radiation safety concerns, particularly in iron-free cyclotrons designed for wide energy ranges.
Implementation Method 1
Acceleration is achieved by applying high frequency (typically radio frequency (RF)) electric fields to an ion beam packet as it spirals outward from the center of an axisymmetric, static magnetic field
Implementation Method 2
The cyclotron frequency varies to compensate for changes to the relativistic mass of the accelerated particles as their energy increases during acceleration and the fact that the magnetic field is varying radially in order to provide beam focusing
Implementation Method 3
actuating a non-axisymmetric pulsed magnetic field (kicker field) to extract the ion beam
Data Source
AI summary
The invention specifies the use of feedback in the radio frequency (RF) drive for a synchrocyclotron, controlling the phase and/or amplitude of the accelerating field as a means to assure optimal acceleration of the beam, to increase the average beam current and to alter the beam orbit in order to allow appropriate extraction as the beam energy is varied. The effect of space charge is reduced by rapid acceleration and extraction of the beam, and the repetition rate of the pulses can be increased. Several means are presented to monitor the phase of the beam in synchrocyclotrons and to adjust the phase and amplitude of the RF to optimize the acceleration of the beam and to adjust the extraction and injection of the beam. Also, the use of a pulsed ion source that matches the acceptance window of the synchrocyclotron is described.