Camelback Effect
Electromagnetism is a branch of physics that deals with all phenomena of electricity and magnetism. This field is the key foundation of our modern age of electricity and information technology. It is governed by a set of fundamental principles encoded in four equations called Maxwell equations, which have been known for approximately 150 years. Every time we harness fundamental effects as prescribed or predicted by this theory, we reap immense benefits in terms of technological advances. Things like electric machines, motors, various electronics devices, circuits, computers, display, sensors and wireless communication all operate based on the basic principles of electromagnetism. This subject is actually considered “classical physics,” which seems to suggest that we have known everything we need to know about it.
recently discovered a subtle hidden feature in electromagnetism — a previously unknown field confinement effect that we’ve named the “camelback effect” in a system of two lines of transverse dipoles.
In electromagnetism, the elementary source of electric field and magnetic field can be respectively modeled as a point charge — a hypothetical charge located at a single point in space — and a dipole, a pair of equal and oppositely charged or magnetized poles separated by a distance. Imagine we line up two rows of magnetic dipoles as shown in Fig (a), and we try to measure the strength of the magnetic field along the center axis. The magnetic field is certainly stronger at the center and diminishes away from it. However, if the length of the dipole line exceeds certain critical length, a surprising effect occurs: the field gets slightly stronger near the edges and produces a field confinement profile that looks like a camel’s back — hence the name of the effect.
This surprising discovery is exciting for a few reasons. First, it represents a new elementary one-dimensional confinement potential in physics, joining the list of well-known potentials such as Coulomb, parabolic, and square well. Second, this effect becomes the key feature that enables this system to serve as a new class of natural magnetic trap called parallel dipole line (PDL) trap as shown in Fig. (b) with many possible exciting applications. This camelback effect and the related PDL magnetic trap can be realized using special cylindrical magnets whose poles are on the curved side as shown in Fig. (b) and a graphite rod as the trapped object.