Magnetic Lens Made of a Single Solenoid for Controlling Bending of Two-Dimensional Ion Beam

TL;DR

This paper introduces a novel magnetic lens design using a single solenoid with adjustable curvature to focus ion beams, enabling new applications like simplified mass spectrometers and educational tools.

Contribution

It presents a new magnetic lens concept based on a single solenoid with variable curvature, offering flexible focusing capabilities and potential for practical applications.

Findings

Infinite curvatures can focus parallel beams to a point.

Design of a simple mass spectrometer using the lens.

Educational implications for teaching electromagnetism.

Abstract

The magnetic field inside an ideal solenoid cavity with an arbitrary cross-section is always constant, while it is always zero outside the solenoid. We can make a solenoid lens that can focus a parallel beam to a point behind it by adjusting the curvature of the solenoid circumference. In this paper, we discuss the design of magnetic lenses ranging from simple geometries to the general ones. We discovered that there are an infinite number of curvatures that can be used to focus the parallel beam to a specific focal point. Using this property, we also present the concept of a simple mass spectrometer by measuring the intensity of the ion captured by a detector placed at the focal point. This result is expected to enrich learning material in undergraduate courses, especially for the topic of electricity and magnetism.