Cyclotron Beam Current Variation System
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Solution Overview
Problem
Existing charged particle therapy systems using cyclotrons lack a fail-safe mechanism for quickly switching on and off the beam and adjusting beam intensity, as they rely on high voltage to control the beam, which can lead to unintended beam continuation if the power fails.
Innovation Solution
A beam current variation system with a deflector and collimator arrangement, where the beam is designed to be dumped in the collimator if the deflector is not powered, ensuring fail-safe switching and continuous intensity variation by adjusting the voltage applied to the deflector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a vertical deflector system with high voltage is used to switch off the beam, then the beam can be switched off, but the system is not fail-safe because if the voltage powering fails, the beam may not be switched off
Solution Approach 1:
The patent inverts the conventional logic by designing the deflector system so that the beam is dumped in the collimator when the deflector is not powered, and only passes through when powered with a suitable voltage. This inversion makes the system fail-safe: if voltage fails, the beam is automatically dumped. The deflector and collimator are aligned such that without voltage, the beam trajectory intersects the collimator, while with voltage applied, the beam is deflected away from the collimator.
2Reliability
If the beam is dumped in the collimator when the deflector is not powered, then the system becomes fail-safe for beam switch off, but the device complexity increases due to specific alignment requirements
Solution Approach 1:
The deflector and collimator are pre-aligned during system setup so that when no voltage is applied to the deflector, the beam trajectory naturally intersects the collimator and is dumped. This preliminary alignment ensures that the fail-safe condition is automatically satisfied without requiring active control or additional components. The geometry is fixed such that the unpowered state corresponds to the safe state.
3Speed
If the deflector system is designed to dump the beam in the collimator when not powered, then quick beam switching is achieved, but the beam intensity adjustment range is constrained
Solution Approach 1:
The patent employs dynamic control of the deflector voltage to achieve both quick switching and continuous intensity adjustment. By varying the voltage applied to the deflector system, the beam deflection angle can be continuously adjusted, allowing the beam intensity to be varied across a wide range. The system transitions from a binary on/off state to a continuously adjustable state, maintaining fast response while adding versatility.
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
The system ensures reliable and quick switching of the beam on and off, and adjustable intensity, maintaining safety and operational efficiency even if the power fails, by automatically dumping the beam in the collimator when voltage is absent.
Implementation Method 1
the deflector system consists of a vertical deflector with two deflector plates being arranged, with respect to the beam direction, downstream from the ion source in the acceleration plane
Implementation Method 2
the beam is dumped in the collimator, if the deflector system is not powered
Data Source
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AI summary
Beam current variation system for a cyclotron, arranged in the inner centre of the cyclotron, downstream from the ion source generating the charged particle beam, the system comprising a deflector system powered by a voltage and a collimator. The beam is dumped in the collimator, if the deflector system (10; 20, 21) is not powered, and the beam is switched on by powering the deflector system with a voltage.