The fusor is an Inertial Electrostatic Confinement fusion device. It can create fusion reactions by accelerating ions by means of an electrostatic field. The electric field is generated by two concentric spherical electrodes, of which the inner one is mostly transparent and strongly negatively charged. The ions are accelerated inwards and most will pass the transparent electrode. After the electrode, they continue converging inwards, creating a high density of high energy ions in the center of the fusor. Collision with each other or with neutral background gas particles then results in fusion reactions.

Although the fusor is probably the most simple fusion device that exists, the physics is far from trivial. The fusor is operated over a wide range of pressures and applied voltages resulting in different operating regimes in which different processes are relevant. Furthermore, the ions are not in thermal equilibrium complicating the physics. Therefore, performance gains can be achieved by studying the fusor and by optimizing the design of the fusor.

The motivation for the fusor research in Eindhoven is threefold: First, the fusor provides a diagnostics test facility for diagnostics developed by the group. The diagnostics tested on the fusor can later be exploited on tokamak experiments. Second, the fusor will be used for educational purposes, by demonstrating fusion plasmas, ion confiment and fusion diagnostics. And finally, to study the fusor physics, with the aim to understand the underlying principles and processes and to optimize the fusion performance.

To optimize and improve the fusor performance, several studies are currently performed on the fusor. The ion density profile is measured by passive spectroscopy to investigate the influence of the operating parameters. Electric potential measurements are performed by using Langmuir and emissive probes to investigate the influence of space charge on the vacuum potential. As the potential determines the ion energies, i.e. the fusion probability, and the ion density improves the collision probability, both projects are essential to improve the fusion rate. Furthermore, a specific fusor phenomena, the electron jet, is being researched by investating the effects of electrode asymmetries.