For 10 points, name these early, particle accelerators named for the sinusoidal time variation of applied voltage and because they are circular.
The namesake parameter of these entities is a frequency given by the magnetic induction times the particle charge-to-mass ratio. These objects utilize a static axial magnetic field, which causes them to fail when relativity becomes significant. The main electrodes of these devices are known as "dees" and were initially used to create betas in the one-megaelectronvolt range by Edmund Wilson. For 10 points, name these early, particle accelerators named for the sinusoidal time variation of applied voltage and because they are circular.
The namesake parameter of these entities is a frequency given by the magnetic induction times the particle charge-to-mass ratio.
cyclotrons