Tunable, Coherent Soft X-Ray Source with Ultracold Electron Micro-Bunches

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Solution Overview

Problem

Current x-ray sources lack the brilliance, coherence, and photon flux required for advanced applications, limiting their use to large-scale facilities like synchrotrons and EUV Free Electron Lasers, and there is no compact, affordable alternative for generating tunable, narrowband, fully coherent, and intense soft X-rays.

Innovation Solution

A compact device combining an Ultra-Cold Electron Source (UCES) with an electron accelerator and a high-power laser in an Inverse-Compton-Scattering setup, utilizing a two-step photo-ionization process to create electron micro-bunches, which are then RF accelerated and compressed, achieving full spatial and temporal coherence.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If large-scale synchrotron facilities or EUV Free Electron Lasers are used, then brilliance, coherence, and photon flux are improved, but device size, cost, and complexity increase significantly

Engineering Contradiction:
ImprovebrillianceVSAvoidfacility scale
Core Design Contradiction:
Illumination intensityVSDevice complexity

Solution Approach 1:

The patent replaces the complex mechanical and infrastructural systems of large-scale synchrotrons with a compact table-top device using laser-plasma interaction. Instead of using large magnetic rings and particle accelerators, the invention uses a focused laser beam to generate electron beams and subsequent X-ray radiation in a much smaller footprint, eliminating the need for kilometer-scale facilities while achieving comparable brilliance.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the operating parameters from conventional electron accelerators to ultra-intense laser parameters. By using laser intensities of 10^18-10^22 W/cm² and focusing to small spot sizes, the system achieves the necessary electron beam energies and densities for high-brilliance X-ray generation in a compact configuration, rather than relying on large-scale accelerator infrastructure.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If conventional x-ray sources are used, then device simplicity is maintained, but coherence and photon flux are insufficient for advanced applications

Engineering Contradiction:
ImprovecoherenceVSAvoidphoton flux
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent employs periodic laser pulsing to generate electron beams with controlled temporal structure. By using pulsed laser operation at appropriate repetition rates and pulse durations, the system produces coherent X-ray bursts with high photon flux, achieving both temporal coherence and productivity that conventional continuous sources cannot provide.

Inventive Principle:
Principle #19Periodic action

3Power

If laser parameters are increased to improve X-ray intensity, then brilliance is improved, but energy consumption and system complexity increase

Engineering Contradiction:
ImproveX-ray intensityVSAvoidlaser energy
Core Design Contradiction:
PowerVSUse of energy by moving object

Solution Approach 1:

The patent implements continuous or high-repetition-rate laser operation to maintain steady X-ray production. By keeping the laser system continuously operational at optimized power levels rather than using intermittent high-power pulses, the system achieves high average X-ray intensity with more efficient energy utilization, reducing peak power requirements and overall energy consumption.

Inventive Principle:
Principle #20Continuity of useful action

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 device generates tunable, narrowband, fully coherent, and intense soft X-ray beams with brilliance comparable to large-scale facilities, enabling applications such as wafer inspection and high-contrast imaging of biological samples.

Implementation Method 1

The device combines an Ultra-Cold Electron Source (UCES) with an electron accelerator and a high-power laser in an Inverse-Compton-Scattering setup. The intense laser beam collides head-on with a counter propagating beam of electrons extracted from the ultra-cold electron source

Methodology Applied
Scientific EffectInverse Compton Scattering: Inverse Compton Scattering

Implementation Method 2

Due to the relativistic Doppler effect the laser photons that bounce off the electrons are converted into (soft) X-ray photons

Methodology Applied
Scientific EffectRelativistic Doppler effect: Doppler Effect

Implementation Method 3

The electron pulses are created by a two-step photo-ionization process of an ultracold atomic gas, which enable precise tailoring of the initial electron density distribution in three dimensions

Methodology Applied
Scientific EffectPhoto-ionization: Photoionisation

Implementation Method 4

The picosecond electron pulse is RF accelerated to a few MeV and simultaneously RF compressed by two orders of magnitude

Methodology Applied
Scientific EffectRF acceleration: Electromagnetic Propulsion

Data Source

PatentEP3874914B1Tunable source of intense, narrowband, fully coherent, soft x-rays
Publication Date: 2025.07.02 TECH UNIV EINDHOVEN
  • EP3874914B1 patent drawingFigure 1~2
  • EP3874914B1 patent drawingFigure 3
  • EP3874914B1 patent drawingFigure 4

AI summary

A device for generating soft x-rays includes an electron source configured to generate an electron beam comprising electron micro- bunches; an electron accelerator configured to accelerate the electron micro-bunches from the electron source; and a laser configured to generate a laser beam (536) colliding with the accelerated electron micro-bunches (534) in a counterpropagating direction to generate the soft x-rays by inverse Compton scattering. The electron source has a magneto-optical trap configured to produce an ultracold atomic gas; two counterpropagating excitation laser beams configured to produce a standing wave for inducing a periodic spatial modulation of the ultracold atomic gas along a beam propagation direction; and an ionization laser configured to induce photo-ionization of the ultracold atomic gas.