A compact Penning trap for light ions

We describe the construction of a novel compact Penning trap from strong permanent magnets for trapping light ions. Our cylindrically symmetric, iron-free magnetic configuration allows fully analytical treatment, is easy to handle and to optimize. The magnetic field inhomogeneity is less than 1% in a volume of 1 cm³ at 0.7 T. The stored H⁺ and H₂⁺ ions in this trap are detected electrically by the rf absorption method. The charge density, total number and storage time of the trapped ions are measured.Dedicated to H. Walther on the occasion of his 60th birthday