penning

Penning is a surname of Dutch origin, and in science it is associated with the work of Frans Penning and with several devices and processes that bear his name. The Penning trap, Penning ionization, and Penning discharge are among the best known usages, reflecting Penning’s influence on early gas discharge and ionization studies.

The Penning trap is a device that confines charged particles using a combination of a strong static magnetic field and a quadrupole electric potential. In this arrangement, particles undergo cyclotron motion in the magnetic field while being axially confined by the electric field, enabling long storage times. Penning traps are widely used for high-precision mass spectrometry, measurements of magnetic properties such as the electron g-factor, and experiments with trapped ions and antimatter.

Penning ionization is a collisional process in which a metastable excited-state atom or molecule transfers its energy to another species, ionizing it without charge transfer. This reaction is important in plasma physics, atmospheric and astrochemistry, and detector physics, where it can influence ion production and chemical pathways at low energies.

Penning discharge, also known as a Penning cell, refers to a hollow cathode glow discharge that uses a magnetic field to confine electrons and enhance ionization efficiency at low pressures. This configuration is employed in Penning gauges for vacuum measurement and in certain low-temperature plasma sources, where stable, efficient ionization is advantageous.

Overall, the term Penning denotes several foundational techniques in spectroscopy, mass spectrometry, and plasma chemistry, named in honor of Frans Penning and reflecting his contributions to early ionization science.