Observation and Modeling of External Rotating-Field-Driven Nonlinear Resonances in a Penning Trap

• Published in: Journal of the Physical Society of Japan Vol. 92; no. 11; p. 1
• Main Authors: Higaki, Hiroyuki, Kojima, Kunihiro, Okamoto, Hiromi, Yoshinaga, Hinako
• Format: Journal Article
• Language: English
• Published: Tokyo The Physical Society of Japan 15-11-2023
• Subjects: Electric dipoles; Harmonic oscillators; Ion density (concentration); Mathematical models; Parameter identification; Rotation
• ISSN: 0031-9015; 1347-4073
• DOI: 10.7566/JPSJ.92.114301

About 105 He+ ions are confined in a multi-ring Penning trap with an additional rotating electric dipole field introduced to enhance the ion density. Dangerous parameter regions where noticeable ion losses occur are experimentally identified depending on the strength of the axial ion confinement force. The experimental data is compiled into a stability map that reveals the existence of several narrow instability bands. A simple Hamiltonian model is constructed to explain the observed instability. In a low-density regime as considered here, it is unnecessary to make any complicated argument about collective modes; all observed ion losses can be interpreted as a consequence of resonances of driven harmonic oscillators. Three-dimensional numerical simulations without the inter-particle Coulomb interaction are performed taking the exact trap geometry into account. The numerical results are shown to agree fairly well with experimental observations and theoretical predictions.