The open-source Plasma Toroid Generator—frequently referred to in maker communities as a DIY "Plasma Bagel" or miniature tokamak—is a compact experimental apparatus that generates a self-sustaining, floating ring of ionized gas. Grounded directly in Nikola Tesla’s early research into high-frequency, electrodeless high-voltage discharges, the machine bypasses traditional internal electrodes that quickly erode. Instead, it uses a custom multi-layer printed circuit board etched with a circular induction drive coil wrapped around a sealed glass globe filled with low-pressure noble gas (typically xenon). Driven by a high-frequency solid-state Class-E RF power oscillator operating at roughly 10–15 MHz and high AC voltage, the primary coil rapidly alternates its magnetic field. This induces a circulating electrical current inside the rarefied gas through pure wireless induction, stripping electrons from the gas atoms to form a glowing, stable plasma donut floating freely within the vacuum chamber.

While classical physics describes this glowing ring as a 3D toroidal inductively coupled plasma (ICP), open-source experimenters and fringe physics researchers often conceptualize these stable toroids as "4D torus fields" due to their unique geometry and self-confining vortex dynamics. The continuously oscillating electromagnetic drive establishes a balanced feedback loop where the plasma ring's own magnetic field interacts with the drive coil's field, allowing the torus to maintain a stable, drifting equilibrium without touching the glass walls. Maker-designed open-source hardware projects (such as those hosted on open repositories like Codeberg and Instructables) provide accessible Gerber files, 3D-printable enclosures, and modern MOSFET circuit schematics. This allows hobbyists and researchers to build, tune, and explore Tesla’s century-old Wireless Energy and field-dynamics concepts right on a workbench.