Laser Plasma Lens for Electron Beam Collimation
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Solution Overview
Problem
Laser-plasma acceleration produces electron bunches with divergence that is difficult to correct using existing devices like magnetic quadrupoles, which leads to significant degradation of emittance and incomplete focusing of short electron packets.
Innovation Solution
A device and method utilizing a wave of focusing electric and magnetic fields created by a laser pulse propagating through a gas cloud to collimate or focus relativistic electrons, allowing simultaneous focusing in both transverse directions and maintaining a compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If magnetic quadrupoles are used to correct electron bunch divergence, then focusing capability is improved, but device complexity and distance requirements increase significantly
Solution Approach 1:
The patent replaces the mechanical magnetic quadrupole system with an optical laser-based plasma focusing system. The laser pulse generates plasma waves that create electric fields for focusing electrons, substituting mechanical electromagnetic components with optical field-based manipulation, thereby reducing device complexity and distance requirements
Solution Approach 2:
The patent introduces plasma as an intermediary medium between the laser pulse and the electron bunch. The laser pulse ionizes the gas to create plasma, which then generates the focusing electric fields through plasma wave oscillations. This intermediary enables efficient energy transfer and focusing without requiring complex direct magnetic quadrupole systems
2Productivity
If magnetic quadrupoles are placed close to the electron source, then focusing efficiency is improved, but electron emittance degradation increases due to divergence
Solution Approach 1:
The patent applies preliminary focusing action by positioning the plasma lens immediately after the electron acceleration stage. The laser pulse that accelerates electrons also creates the plasma lens in situ, providing immediate focusing action before significant divergence can occur, thus preserving emittance while achieving high focusing efficiency
Solution Approach 2:
The patent merges the acceleration and focusing functions into a single integrated process. The same laser pulse that accelerates electrons via plasma wakefield also generates the plasma lens for focusing, combining two functions that were previously separate (acceleration and focusing stages) into one unified mechanism
3Duration of action of moving object
If conventional accelerators are used to generate short electron bunches, then bunch duration is reduced, but device size and complexity increase significantly
Solution Approach 1:
The patent replaces conventional large-scale mechanical accelerators with a compact laser-plasma acceleration system. The high-intensity laser pulse creates plasma waves that accelerate electrons to high energies over extremely short distances (millimeters instead of meters), producing short bunches without requiring large device dimensions
Solution Approach 2:
The patent utilizes periodic plasma oscillations driven by the laser pulse to accelerate electrons. The laser pulse duration (femtosecond scale) naturally limits the acceleration time, producing inherently short electron bunches. The periodic nature of plasma wave oscillations enables efficient energy transfer within this brief time window
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
Effectively collimates or focuses relativistic electron bunches with minimal divergence and energy variation, improving the emittance and focusing efficiency compared to traditional methods, especially for short and high-energy electron packets.
Implementation Method 1
A so-called 'laser-plasma' electron acceleration process is known. This process makes it possible to generate a bunch of high-energy electrons - typically a few hundred MeV - by focusing an intense laser pulse in a gas jet.
Implementation Method 2
This laser pulse locally ionizes the gas cloud, forming focusing electric and magnetic fields. This wave of focusing fields moves following the laser pulse.
Implementation Method 3
the packet of electrons entering a plasma generates, in its wake, a wave of focusing electric fields
Data Source
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AI summary
The invention relates to a device (10) for collimation or focusing of a relativistic electron packet (12), obtained in particular by laser-plasma acceleration, comprising a gas cloud (14) and a laser capable of emitting a laser pulse (18) focused in the gas cloud (14) in order to create therein a wave of focusing electric and magnetic fields (22). The invention also relates to a device for emission of a collimated or focused relativistic electron packet. The invention further relates to a collimation or focusing method for a relativistic electron packet, and to methods for emission of a collimated or focused relativistic electron packet.