Levitated magnetic dipole system can simultaneously trap positrons and electrons

A compact, levitated dipole system can simultaneously confine both positrons and electrons during plasma experiments. Saitoh et al. reviewed the physics required for such a dipole system to work and suggested improvements to the system by drawing inspirations from planetary magnetospheres.

“It has long been known that the planetary magnetospheres are excellent natural trap systems for charged particles. This geometry has a long history of study in the community of plasma physics, especially for fusion-oriented high-temperature plasmas,” said author Haruhiko Saitoh. “However, the construction of a compact artificial magnetosphere for basic plasma and atomic physics experiments, like the creation of electron-positron plasmas, was only recently started.”

According to the authors, a compact levitation system based on a miniaturized magnetosphere design is technically feasible. A permanent magnet can be levitated with an upward magnetic force generated by a circular coil, which would allow it to confine particles within the generated field long enough to be practical.

“This means that now we have the concept of a handy trap to simultaneously confine positively and negatively charged particles in a laboratory,” Saitoh said.

Other similar systems can only trap particles with charges of the same sign, but the authors note the importance of being able to confine various particles simultaneously.

“Thanks to the pure magnetic trap method of the levitated dipole, in principle, one can confine various charged particles with different charge polarity, mass and even ion valence,“ Saitoh said. “This enables stable confinement of novel combinations of ions and other charged particles in a laboratory, which may be used for studies on the evolution of molecules in the space environment, for example.”

Source: “A levitated magnetic dipole configuration as a compact charged particle trap,“ by H. Saitoh, M. R. Stoneking, and T. Sunn Pedersen, Review of Scientific Instruments (2020). The article can be accessed at https://doi.org/10.1063/1.5142863 .