Virtual Gap Dielectric Wall Accelerator Parasitic Coupling
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Solution Overview
Problem
Conventional dielectric wall accelerators face issues with parasitic coupling, high energy requirements, large number of switches, and radial defocusing, limiting their efficiency and compactness, particularly in applications like proton accelerators for medical use.
Innovation Solution
A dielectric wall accelerator with a virtual moving accelerating gap is created by controlling the conductivity of the tube sequentially using light illumination or photoconductive switches, allowing for a localized voltage concentration that moves along the tube, reducing the need for physical gaps and enhancing focusing capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If strip Blumleins are used in a DWA configuration, then the accelerator can be made more compact with fewer switches, but parasitic coupling between lines causes temporal distortion and amplitude reduction
Solution Approach 1:
A conducting tube acts as an intermediary element to eliminate parasitic coupling between Blumlein lines. The tube provides a controlled electrical path that prevents field leakage and unwanted interaction between adjacent lines, thereby maintaining pulse quality while allowing the use of fewer switches.
Solution Approach 2:
The conductivity of the beam pipe is dynamically changed by introducing a conducting tube that can be selectively activated. This parameter change allows the system to transition between different operational modes, enabling compact design with fewer switches while maintaining pulse integrity through controlled conductivity distribution.
2Strength
If Blumlein lines are charged to high voltage for extended periods, then maximum gradient is achieved, but electrical stress on switches increases significantly
Solution Approach 1:
The conducting tube is pre-positioned and configured before the acceleration process begins. By establishing the conductive path in advance, the system can maintain high voltage gradients without subjecting switches to prolonged electrical stress, as the tube assumes part of the voltage burden.
Solution Approach 2:
The conducting tube serves as a mediator that分担s the electrical stress from the switches. By providing an alternative current path and voltage distribution mechanism, the tube reduces the burden on switches during high voltage charging periods.
3Ease of operation
If the beam pipe is conducting, then an accelerating electric field is present only in gaps between stages, but the accelerating field occupies only a small fraction of the axial length
Solution Approach 1:
The system transitions from a static conducting beam pipe to a dynamic configuration where conductivity is selectively applied. The conducting tube can be activated in specific regions and at specific times, allowing the accelerating field to be distributed more effectively along the axial length while maintaining operational simplicity.
Solution Approach 2:
Instead of a uniformly conducting beam pipe, the invention applies conductivity locally where needed. The conducting tube is positioned and activated in specific regions to create accelerating fields precisely where required, optimizing both field distribution and acceleration efficiency.
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 eliminates parasitic coupling, reduces the number of switches, and provides efficient acceleration with fewer electrical stress issues, enabling a more compact and efficient proton accelerator suitable for medical applications.
Implementation Method 1
controlling the conductivity of the tube sequentially at localized regions by light illumination or other means
Implementation Method 2
an accelerating electric field is present only in the gaps between accelerator stages
Data Source
AI summary
A virtual, moving accelerating gap is formed along an insulating tube in a dielectric wall accelerator (DWA) by locally controlling the conductivity of the tube. Localized voltage concentration is thus achieved by sequential activation of a variable resistive tube or stalk down the axis of an inductive voltage adder, producing a “virtual” traveling wave along the tube. The tube conductivity can be controlled at a desired location, which can be moved at a desired rate, by light illumination, or by photoconductive switches, or by other means. As a result, an impressed voltage along the tube appears predominantly over a local region, the virtual gap. By making the length of the tube large in comparison to the virtual gap length, the effective gain of the accelerator can be made very large.