User:Jdsaassasasa/sandbox

A fusor is a device that uses an electric field to heat ions to nuclear fusion conditions. The machine induces a voltage between two metal cages, inside a vacuum. Positive ions fall down this voltage drop, building up speed. If they collide in the center, they can fuse. This is one kind of an inertial electrostatic confinement device – a branch of fusion research.

A Farnsworth–Hirsch fusor is the most common type of fusor. This design came from work by Philo T. Farnsworth in 1964 and Robert L. Hirsch in 1967. A variant type of fusor had been proposed previously by William Elmore, James L. Tuck, and Ken Watson at the Los Alamos National Laboratory though they never built the machine.

Fusors have been built by various institutions. These include academic institutions such as the University of Wisconsin–Madison, the Massachusetts Institute of Technology and government entities, such as the Atomic Energy Organization of Iran and the Turkish Atomic Energy Authority. Fusors have also been developed commercially, as sources for neutrons by DaimlerChrysler Aerospace and as a method for generating medical isotopes. Fusors have also become very popular for hobbyists and amateurs. A growing number of amateurs have performed nuclear fusion using simple fusor machines. However, fusors are not considered a viable concept for large-scale energy production by scientists.

Mechanism
For every volt that an ion of ±1 charge is accelerated across it gains 1 electronvolt in energy, similar to heating a material by 11,604 kelvins in temperature (T = eV / kB, where T is the temperature in kelvins, eV is the energy of the ion in electronvolts, and kB is the Boltzmann constant). After being accelerated by 15 kV a singly-charged ion has a kinetic energy of 15 keV, similar to the average kinetic energy at a temperature of approximately 174 megakelvins, a typical magnetic confinement fusion plasma temperature. Because most of the ions fall into the wires of the cage, fusors suffer from high conduction losses. On a bench top, these losses can be at least five orders of magnitude higher than the energy released from the fusion reaction, even when the fusor is in star mode. Hence, no fusor has ever come close to break-even energy output. The common sources of the high voltage are ZVS flyback HV sources and neon-sign transformers. It can also be called an electrostatic particle accelerator.

An illustration of the basic mechanism of fusion in fusors. (1) The fusor contains two concentric wire cages: the cathode is inside the anode. (2) Positive ions are attracted to the inner cathode, they fall down the voltage drop. The electric field does work on the ions, heating them to fusion conditions. (3) The ions miss the inner cage. (4) The ions collide in the center and may fuse.

History
The fusor was originally conceived by Philo T. Farnsworth, better known for his pioneering work in television. In the early 1930s, he investigated a number of vacuum tube designs for use in television, and found one that led to an interesting effect. In this design, which he called the "multipactor", electrons moving from one electrode to another were stopped in mid-flight with the proper application of a high-frequency magnetic field. The charge would then accumulate in the center of the tube, leading to high amplification. Unfortunately it also led to high erosion on the electrodes when the electrons eventually hit them, and today the multipactor effect is generally considered a problem to be avoided.

What particularly interested Farnsworth about the device was its ability to focus electrons at a particular point. One of the biggest problems in fusion research is to keep the hot fuel from hitting the walls of the container. If this is allowed to happen, the fuel cannot be kept hot enough for the fusion reaction to occur. Farnsworth reasoned that he could build an electrostatic plasma confinement system in which the "wall" fields of the reactor were electrons or ions being held in place by the multipactor. Fuel could then be injected through the wall, and once inside it would be unable to escape. He called this concept a virtual electrode, and the system as a whole the fusor.

Design
Farnsworth's original fusor designs were based on cylindrical arrangements of electrodes, like the original multipactors. Fuel was ionized and then fired from small accelerators through holes in the outer (physical) electrodes. Once through the hole they were accelerated towards the inner reaction area at high velocity. Electrostatic pressure from the positively charged electrodes would keep the fuel as a whole off the walls of the chamber, and impacts from new ions would keep the hottest plasma in the center. He referred to this as inertial electrostatic confinement, a term that continues to be used to this day.The voltage between the electrodes needs to be at least 25,000 Volts for fusion to occur.

Work at Farnsworth Television labs
All of this work had taken place at the Farnsworth Television labs, which had been purchased in 1949 by ITT Corporation, as part of its plan to become the next RCA. However, a fusion research project was not regarded as immediately profitable. In 1965, the board of directors started asking Harold Geneen to sell off the Farnsworth division, but he had his 1966 budget approved with funding until the middle of 1967. Further funding was refused, and that ended ITT's experiments with fusion.

Things changed dramatically with the arrival of Robert Hirsch, and the introduction of the modified Hirsch–Meeks fusor patent. New fusors based on Hirsch's design were first constructed between 1964 and 1967. Hirsch published his design in a paper in 1967. His design included ion beams to shoot ions into the vacuum chamber.

The team then turned to the AEC, then in charge of fusion research funding, and provided them with a demonstration device mounted on a serving cart that produced more fusion than any existing "classical" device. The observers were startled, but the timing was bad; Hirsch himself had recently revealed the great progress being made by the Soviets using the tokamak. In response to this surprising development, the AEC decided to concentrate funding on large tokamak projects, and reduce backing for alternative concepts.

Recent developments
George H. Miley at the University of Illinois reexamined the fusor and re-introduced it into the field. A low but steady interest in the fusor has persisted since. An important development was the successful commercial introduction of a fusor-based neutron generator. From 2006 until his death in 2007, Robert W. Bussard gave talks on a reactor similar in design to the fusor, now called the polywell, that he stated would be capable of useful power generation. Most recently, the fusor has gained popularity among amateurs, who choose them as home projects due to their relatively low space, money, and power requirements. An online community of "fusioneers", The Open Source Fusor Research Consortium, or Fusor.net, is dedicated to reporting developments in the world of fusors and aiding other amateurs in their projects. The site includes forums, articles and papers done on the fusor, including Farnsworth's original patent, as well as Hirsch's patent of his version of the invention.

COVID-19 Vaccines Global Access, abbreviated as COVAX, is a worldwide initiative aimed at equitable access to COVID-19 vaccines directed by Gavi, the Vaccine Alliance (formerly the Global Alliance for Vaccines and Immunization, or GAVI), the Coalition for Epidemic Preparedness Innovations (CEPI), and the World Health Organization (WHO). It is one of the three pillars of the Access to COVID-19 Tools Accelerator, an initiative begun in April 2020 by the WHO, the European Commission, and the government of France as a response to the COVID-19 pandemic. COVAX coordinates international resources to enable low-to-middle-income countries equitable access to COVID-19 tests, therapies, and vaccines. By 15 July 2020, 165 countries – representing 60% of the human population – had joined COVAX. However, as of 11 April 2021, COVAX is falling short of its goal, having delivered 38.5 million doses despite a goal of 100 million by the end of March.

Vaccine candidates
As of 9 May 2021, the WHO has approved the Oxford–AstraZeneca, the Pfizer–BioNTech, the Moderna as well as the Sinopharm BBIBP-CorV and Johnson & Johnson vaccines for emergency use. These vaccines can be distributed as part of COVAX.

Many of the countries that will benefit from COVAX have "limited regulatory capacity" and depend on WHO's authorisations. By early 2021, WHO was reviewing 11 potential COVID-19 vaccines for its Emergency Use Listing (EUL). The first vaccine WHO authorised for its EUL on 31 December 2020 was the Pfizer–BioNTech COVID-19 vaccine—an RNA vaccine developed by BioNTech in cooperation with the American company Pfizer sold under the brand name Comirnaty.

The WHO stated in a press release on 24 August 2020 that COVAX had nine CEPI-supported vaccine candidates and nine candidates undergoing trials, giving it the largest selection of COVID-19 vaccinations in the world. By December 2020, COVAX had finalized negotiations with other manufacturers that gave it access to two billion vaccine doses.