How Ernest Lawrence Invented the Cyclotron Particle Accelerator
This 1934 patent describes the cyclotron, a machine that uses magnetic and electric fields to whip particles into high speeds for scientific research.
Original patent title: “Method and apparatus for the acceleration of ions”
This 1934 patent describes the cyclotron, a machine that uses magnetic and electric fields to whip particles into high speeds for scientific research. Granted to Research Corp in 1934 with 114 forward citations, and it is now in the public domain.
Key facts
Coverage
What does this patent actually cover?
The invention, known as a cyclotron, uses a vacuum chamber placed between the poles of a large electromagnet. Inside the chamber are two hollow, D-shaped electrodes. As ions are injected into the center, an alternating electric field switches the charge of these electrodes, pulling the ions across the gap and causing them to spiral outward in a circular path. By repeating this process, the ions gain massive amounts of kinetic energy before being directed at a target.
The gap
What does this patent NOT cover?
- Does not cover linear particle accelerators which move particles in a straight line rather than a circle.
- Does not cover the specific chemical or radioactive properties of the particles being accelerated.
- Does not cover non-magnetic methods of particle acceleration like electrostatic Van de Graaff generators.
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
What made this novel
Lawrence realized that by using a constant magnetic field, the time it takes for a particle to complete a circular orbit remains the same regardless of its speed, allowing for simple, synchronized acceleration.
The Patent Drawing
Schematic visualization of the patent's claim structure. Hand-drawn diagrams in progress for each landmark patent.
Where you've seen this
Real-world examples
Modern proton therapy machines for cancer treatment
Radioisotope production for medical imaging
University physics research laboratories
Why it matters
The bigger picture
This invention launched the era of high-energy physics. It allowed researchers to study the atomic nucleus by smashing particles into targets, leading to the discovery of new elements and isotopes. It remains the foundational design for many medical and research accelerators used today.
Filed
January 26, 1932
Granted
February 20, 1934
Market context
Who's building on this
Companies in this space
Major research institutions like CERN and national laboratories in the US continue to refine accelerator technology. Companies like Varian Medical Systems build on these principles for clinical cancer treatment devices.
Market impact
The cyclotron enabled the field of nuclear medicine and provided the tools necessary to map the fundamental structure of matter. It shifted physics from a desk-based science to a large-scale, experimental industry.
Claim 1 — Plain English
What this patent covers
The invention, known as a cyclotron, uses a vacuum chamber placed between the poles of a large electromagnet. Inside the chamber are two hollow, D-shaped electrodes. As ions are injected into the center, an alternating electric field switches the charge of these electrodes, pulling the ions across the gap and causing them to spiral outward in a circular path. By repeating this process, the ions gain massive amounts of kinetic energy before being directed at a target.
The clever bit
Lawrence realized that by using a constant magnetic field, the time it takes for a particle to complete a circular orbit remains the same regardless of its speed, allowing for simple, synchronized acceleration.
What it does not cover
- Does not cover linear particle accelerators which move particles in a straight line rather than a circle.
- Does not cover the specific chemical or radioactive properties of the particles being accelerated.
- Does not cover non-magnetic methods of particle acceleration like electrostatic Van de Graaff generators.
Patent Journey
From filing to expiry
PatentBrief Score
Impact Score
Moderate
Citation count
40/40
Highly cited
Claim breadth
0/20
Narrow claimsclaimsThe numbered statements at the end of a patent that legally define what the inventor owns.Read more →
Recency
0/20
Older than 20 years
Assignee scale
0/20
Independent or smaller assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more →
PatentBrief Impact Score — based on citation count, claim breadth, recency, and assignee scale. Not a legal assessment.
Heuristic Value Estimate
What this patent might be worth
$42K – $134K
Midpoint $84K · expired or expiring · industry ×1.4
Heuristic only — blends forward/backward citation counts, claim scope, time remaining, litigation history, and CPC-derived industry baseline. Real valuations need a professional appraisal.
Concepts involved
Citations
Patent lineage
Cite this patent
Lawrence, E. O. (1934). How Ernest Lawrence Invented the Cyclotron Particle Accelerator (U.S. Patent No. 1,948,384). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/1948384/cyclotron-lawrence
Auto-generated from the patent record. Double-check author order and the issue date against the official USPTO document before submitting.
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Common Questions
Frequently Asked Questions
What does How Ernest Lawrence Invented the Cyclotron Particle Accelerator cover?
This 1934 patent describes the cyclotron, a machine that uses magnetic and electric fields to whip particles into high speeds for scientific research.
Who owns patent US 1948384?
Research Corp owns this patent, granted in 1934.
When does this patent expire?
This patent has expired and is now in the public domain — anyone can use the invention freely.
What is patent US 1948384 cited by?
This patent has been cited by 114 later patents that build on its ideas.
What problem does this patent solve?
This invention launched the era of high-energy physics. It allowed researchers to study the atomic nucleus by smashing particles into targets, leading to the discovery of new elements and isotopes. It remains the foundational design for many medical and research accelerators used today.
What does this patent NOT cover?
Does not cover linear particle accelerators which move particles in a straight line rather than a circle.
Patent monitoring