Abstract
Using a three-dimensional numerical simulation, the dependencies of the electron cloud (virtual cathode) on the distance between the coils in the Polywell fusion reactor were examined. In the Polywell, the role of a stable and energetic virtual cathode is crucial for fusion. It is shown that by increasing the spacing coils, the electron confinement time increases initially and then remains constant. Using the simulation results, an optimum range for the spacing of coils was suggested, which leads to a longer and more effective confinement. The results obtained can be used to design future devices in order to have a more effective virtual cathode.
Highlights
The Polywell reactor is a magnetic multipole plasma confinement device that is an improved model of an inertial electrostatic confinement fusion (IECF) device
In order to solve this problem, replacing a physical cathode with a virtual cathode was proposed by Lavrent’ev,5 and this idea was executed by Bussard and called the “Polywell.”6–8 The Polywell device consists of three pairs of electric current coils, with the axis of each pair of coils corresponding to each of the Cartesian axes; it can be assumed that each coil is located on one of the cube faces
Increasing the confinement time of electrons and, as a result, maintaining the virtual cathode are very important in the performance of the Polywell reactor
Summary
The Polywell reactor is a magnetic multipole plasma confinement device that is an improved model of an inertial electrostatic confinement fusion (IECF) device. In IEC systems, the collision of trapped ions with electrodes, especially the internal grad (physical cathode), causes a lot of energy loss and even leads to melting of the cathode. Such a loss mechanism is one of the main obstacles to the use of IEC systems as a source of fusion power.. The electrons’ escape from point cusps, which reduces the electron confinement time, is known as a major source of loss because, when an energetic dense electron cloud is not created with sufficient persistence time, the potential well depth is not great enough for the ions to be accelerated to the required degree for a fusion reaction. In order to increase the confinement time, the point cusps should be blocked and electrons from escaping (for example, by placing reflective plates at the point cusps location). for a certain (s), it is important to know which cusps have the most losses
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