Resonant Photoionization Subsystem for Ion Beam Brightness
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Solution Overview
Problem
Conventional photoionization systems in photoionized gas ion sources (PIGIS) fail to achieve high ionization efficiency, create ions with low chromatic energy spread, maintain transverse velocity variance similar to cold neutral atoms, and suppress the creation of multiple ions in close proximity, due to their design not utilizing resonant structures in the photoionization spectrum.
Innovation Solution
A photoionization subsystem with a controllable electric field and laser radiation that resonantly ionizes gaseous atoms, using resonances in the photoionization spectrum to enhance ion production, including a vacuum chamber evacuated to less than 10−6 millibar to contain atoms, electrodes, laser beams, and the resulting ion beam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional photoionization systems use lasers with photon energy equal to the electric field-free ionization potential, then the system design is simple, but ionization efficiency is low
Solution Approach 1:
The patent changes the photon energy parameter of the laser from matching the electric field-free ionization potential to matching the resonant frequency in the photoionization spectrum. This parameter change enables resonant enhancement of photoionization, dramatically improving ionization efficiency by exploiting quantum mechanical resonance effects in the atom's energy level structure.
Solution Approach 2:
The patent applies a controllable electric field to the atomic vapor before photoionization occurs. This preliminary action modifies the atomic energy levels (Stark effect), creating resonant structures in the photoionization spectrum that can be exploited by tuning the laser frequency, thereby enhancing ionization efficiency.
2Manufacturing precision
If conventional photoionization systems do not excite resonant structure, then the system configuration is simple, but chromatic energy spread of ions is high
Solution Approach 1:
The patent tunes the laser frequency to match resonant transitions in the photoionization spectrum. This parameter adjustment ensures that atoms absorb photons at specific resonant frequencies, leading to more uniform ionization conditions and reduced chromatic energy spread in the resulting ion beam.
3Manufacturing precision
If conventional photoionization systems use standard laser configurations, then the system is easy to operate, but transverse velocity variance of ions is high
Solution Approach 1:
The patent creates a localized region with a controllable electric field where photoionization occurs. By confining the ionization process to this specific region with optimized field conditions and resonant laser illumination, the transverse velocity distribution of produced ions is better controlled, resulting in lower transverse velocity variance.
4Productivity
If conventional photoionization systems do not use resonant enhancement, then the system design is straightforward, but multiple ions are created in close proximity
Solution Approach 1:
The patent uses resonant photoionization with carefully controlled laser frequency and electric field parameters to achieve more uniform and controlled ion production. The resonant enhancement concentrates ionization events in a more predictable manner, reducing the random clustering of multiple ions in close proximity.
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 solution achieves improved ionization efficiency, low chromatic energy spread, reduced transverse temperature of ions, and suppressed creation of multiple ions in close proximity, enhancing the performance of PIGIS for focused ion beam applications.
Implementation Method 1
photoionization of gaseous atoms to produce a source of charged particles and incorporates a photoionization subsystem having one or more beams of laser radiation that ionize gaseous atoms to form pairs of ion and electrons
Implementation Method 2
resonant enhancement of photoionization of gaseous atoms... population of atoms having a photoionizing resonance in the applied electric field... ionizing at least a portion of the atoms having laser radiation applied using the photoionizing resonance
Implementation Method 3
The electric field may also be configured to accelerate the produced ions thereby forming a beam of ions
Implementation Method 4
a vacuum chamber evacuated to less than about 10−6 millibar configured to contain at least the population of atoms, at least a portion of the electrodes, the portion of the beams of laser radiation that overlap with the atoms, and the produced beam of ions
Data Source
AI summary
A system and method for using a high-performance photoionization subsystem are disclosed. Embodiments of the present disclosure employ narrow bandwidth laser radiation to selectively excite ionizing resonant states of gaseous atoms in electric fields. This subsystem and method may be incorporated in an ion source producing ions by photoionizing gaseous atoms; the resultant ions may be employed to efficiently produce an ion beam of high brightness.