Synchrocyclotron Variable Energy Beam Extraction
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Solution Overview
Problem
Existing synchrocyclotrons face challenges in efficiently extracting beams of charged particles at varying energies, particularly due to the inability to easily vary the magnitude of the magnetic field bump and the inability to extract beams at energies outside the nominal energy range, which limits their application in fields requiring rapid energy switching and high dose rates.
Innovation Solution
The synchrocyclotron employs first and second instability coil units to create a magnetic field bump of varying magnitudes, allowing for the selection of extraction energies by generating a resonance instability through specific magnetic field conditions, enabling the extraction of charged particles over a broad energy range from 20% to 100% of the nominal energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a magnetic field bump is used to extract the beam, then the beam extraction is achieved, but the magnitude of the magnetic field bump cannot be easily varied to extract beams at different energies
Solution Approach 1:
The patent applies dynamics by making the magnetic field bump magnitude variable and adjustable. The instability coil units are designed to generate magnetic field bumps with magnitudes that can be dynamically changed to match different offset amplitudes at various extraction radii, enabling beam extraction at multiple energy levels without requiring a completely different extraction system for each energy.
Solution Approach 2:
The patent changes the parameter of magnetic field bump magnitude to enable extraction at different energies. By adjusting the magnitude of the magnetic field bump generated by the instability coil units, the system can match the required offset amplitude at different extraction radii (R1, R2), thereby extracting beams at different energies (E1, E2) from the synchrocyclotron.
2Reliability
If the radial tune is set to 1, then the offset amplitude is minimized, but the beam becomes unstable due to resonance
Solution Approach 1:
The patent changes the radial tune parameter from exactly 1 to a value close to 1 (within the range 0.95 to 1.05). This parameter adjustment allows the system to minimize the required offset amplitude for extraction while avoiding the resonance instability that occurs at exactly νr = 1, thus achieving both beam stability and extraction efficiency.
3Adaptability or versatility
If the magnetic field bump magnitude is increased to extract beams at lower energies, then extraction is achieved, but the beam orbit is excessively offset causing instability
Solution Approach 1:
The patent adjusts the parameter of magnetic field bump magnitude to match the specific offset amplitude required at each extraction radius. Rather than using a fixed or excessively large bump magnitude, the system varies the bump magnitude parameter to precisely match the required offset at each radius (R1, R2), ensuring stable extraction at different energies without excessive orbit offset.
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 solution allows for rapid and efficient extraction of charged particles at varying energies, enhancing the capability of synchrocyclotrons to deliver beams with fast variable energy and high dose rates, simplifying the beam extraction process and expanding their application potential.
Implementation Method 1
a magnetic field bump, which magnitude can be controlled over an azimuthal sector of a given azimuthal angle (θc)... ΔBz0(Ri, νr) is the maximum value of the bump amplitude at radius Ri
Implementation Method 2
generate a resonance instability of the successive orbits of average radius, R ≥ Ri
Implementation Method 3
The acceleration of the particles is driven by an RF-alternating electric field... in synchrocyclotrons, the frequency of the RF-alternating electric field varies to compensate for relativistic effects
Implementation Method 4
the frequency of the RF-alternating electric field varies to compensate for relativistic effects as the particles' velocity approaches the speed of light
Implementation Method 5
the trajectory of the particles is guided along successively larger orbits on a plane (X, Y) of average radius (R) by the z-component (Bz) of a main magnetic field (B)
Data Source
Figure 1~2
Figure 3~4(b)
Figure 5(a)~5(e)
AI summary
The present invention concerns a synchrocyclotron for extracting charged particles accelerated to any extraction energy (Ei) comprised between a low energy (E1) and a high energy (E2), the synchrocyclotron comprising a magnetic unit comprising N valley sectors and N hill sectors, and being configured for creating z-component (Bz) of a main magnetic characterized by a radial tune (vr) of the successive orbits different from 1 and comprised within 1 ± 0.1 for all values of the average radius (R), comprised between a low radius (R1) and a high radius (R2), corresponding to respective average radial positions of the charged particles at the low and high energies (E1, E2), The synchrocyclotron comprises a first instability coil unit (51) and a second instability coil unit (52) configured for creating, when activated by a source of electric power, a field bump of amplitude (ΔBz(R)) increasing radially. The amplitude of the field bump can be varied to reach the value of the offset amplitude (ΔBz0(Ri, vr)) at the average instability onset radius (Ri). The offset amplitude (ΔBz0(Ri, vr)) is the minimal amplitude of the field bump at the average instability onset radius (Ri) required for sufficiently offsetting the centre of the orbit of average instability onset radius (Ri) to generate a resonance instability with, a combination of harmonic 2 and gradient of harmonic 2, to extract the beam of charged particle at the average instability onset radius (Ri).