This article will provide the basis for the manufacture of internal electrostatic confinement-type fusion devices. The Farnsworth-Hirsch fusor and the related Hirsch-Meeks fusor are fusion reactor designs based on the principles of inertial electrostatic confinement, that is, the use of electrostatic potential to confine the fuel.
This fusion technology is in contrast to other methods of confinement, such as inertial, magnetic and gravitational such as fusion in stars Its function can best be described as a spherical, electrostatic, particle accelerator. It is through this acceleration that the charged particles gain enough energy to collide in a fusion reaction. The device consists of a vacuum chamber containing two electrodes, usually arranged as concentric spheres.
The inner electrode grid is charged negatively with high-voltage transformers and the outer electrode grid is grounded to provide a reference voltage for the negatively charged inner grid.
The immense differences in charges between the two electrodes create a powerful electric field that ionises the gas in the chamber. The negatively charged electrons are repelled by the deeply negative potential of the inner cathode and are carried to the region of lower potential once they are ionised by the outer grid.
The remaining positively charged ions are attracted by the deeply negative cathode and accelerate towards the centre. The inner electrode, constructed as an empty grid and not a solid sphere, allows the positive ion to accelerate past the inner grid towards the centre point of the chamber. The strong electrical field, being spherical, accelerates ions towards the centre from all radial points on the sphere, and as the positive ions reach the centre point of the chamber, they collide into ions racing down towards the centre from the opposite side of the sphere. Their combined kinetic energy is enough to overcome the repulsive nature of the Coulomb Barrier and
Create a fusion reaction.
Multiple theoretical concepts are required to fully understand the operation of the fusor. In order to create a plasma, ions must be trapped inside the cathode grid. Therefore, an understanding of the potential well is needed in order to describe how the ions are contained. The size and shape of the potential well vary with the ion current in the region. Once the plasma is created, it must be maintained. Therefore, how the plasma reacts to and moves in the electric field must be known in order to maintain a stable plasma.
Purpose:
A Farnsworth style fusor, using the process of inertial electrostatic confinement, will be used to ionize trace hydrogen atoms found in the atmosphere inside of a container under vacuum. These ionised atoms will continuously accelerate towards a centre anode charged by a 15-kilo-volt transformer. The accelerating ions will, in theory, fuse creating an unstable Helium isotope which will stabilise itself by releasing energy in either the form of a proton, neutron, or gamma rays.
Photon radiation produced by the fusor:
The photon radiation power is measured for hydrogen and deuterium plasmas at different power settings of the fusor. By comparing the radiation power measured by hydrogen and deuterium it is shown that the high-energy protons produced in a deuterium plasma have a negligible contribution to the radiation power. This result is according to the model. The radiation power predicted by the model is below background levels up to theoretical voltages across the fusor of 55 kV.
X-Radiation Escape:
Gamma rays in the energy region below 200 keV are detected almost entirely by the photoelectric process. The ejection of a photoelectron from the K shell of an atom is followed by the emission of characteristic x-rays. The probability for x-ray escape may be calculated as a function of energy and geometry or may be determined experimentally.
Thermalization of the ion velocities:
When they first fall into the centre of the fusor, the ions will all have the same energy, but the velocity distribution will rapidly approach a Maxwell–Boltzmann distribution. This would occur through simple Coulomb collisions in a matter of milliseconds, but beam-beam instabilities will occur orders of magnitude faster still. In comparison, any given ion will require a few minutes before undergoing a fusion reaction, so the monoenergetic picture of the fusor, at least for power production, is not appropriate. One consequence of thermalization is that some of the ions will gain enough energy to leave the potential well, taking their energy with them, without having undergone a fusion reaction.
Power density:
Because the electric field made by the cages is negative, it cannot simultaneously trap both positively charged ions and negative electrons. Hence, there must be some regions of charge accumulation, which will result in an upper limit on the achievable density. This could place an upper limit on the machine's power density, which may keep it too low for power production.
Modes of operation:
Farnsworth–Hirsch fusor during operation in so-called "star mode" characterised by "rays" of glowing plasma which appear to emanate from the gaps in the inner grid. Fusors have at least two modes of operation (possibly more): star mode and halo mode. Halo mode is characterised by a broad symmetric glow, with one or two electron beams exiting the structure. There is little fusion. The halo mode occurs in higher-pressure tanks, and as the vacuum improves, the device transitions to star mode. Star mode appears as bright beams of light emanating from the device centre.
Conclusions:
I hope to confirm predictions that the fusor will produce trace amounts of radiation as an effective example of a small-scale nuclear fusion device. The device will certainly not produce any positive net energy, a state which has become the goal of multiple fusion research laboratories worldwide using exponentially higher power concepts of the fusor’s fundamental nuclear fusion method.
Comments