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| Main Authors: | , , , |
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| Format: | Preprint |
| Published: |
2026
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2601.09189 |
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Table of Contents:
- Adiabatic invariants are fundamental to plasma physics but are often treated as purely theoretical concepts in undergraduate courses due to the difficulty of experimentally demonstrating them. This paper presents a pedagogical experiment to visualize and quantitatively verify the conservation of the magnetic moment ($μ$) and the longitudinal invariant ($J$) using a standard educational electron charge-to-mass ratio apparatus configured as a magnetic bottle. By analyzing long-exposure photographs of the electron beam trajectory, we reconstructed the helical motion and calculated the invariants under different magnetic field configurations. Our results verify the conservation of the longitudinal invariant ($J$) with a ratio of 0.98 between configurations. The magnetic moment ($μ$) exhibited a coefficient of variation of approximately 7\%, a deviation consistent with the presence of collisional effects in the tube. These findings demonstrate that complex plasma dynamics can be effectively studied using accessible laboratory equipment, providing a valuable bridge between theory and experiment for physics students.