such as electrons, positrons, and protons may be separated from their common surrounding. This can be accomplished by e.g. thermionic emission or arc discharge. The following devices are commonly used as sources for particle beams:
Charged beams may be further accelerated by use of high resonant, sometimes also superconducting, microwave cavities. These devices accelerate particles by interaction with an electromagnetic field. Since the wavelength of hollow macroscopic, conducting devices is in the radio frequency band, the design of such cavities and other RF devices is also a part of accelerator physics. More recently, plasma acceleration has emerged as a possibility to accelerate particles in a plasma medium, using the electromagnetic energy of pulsed high-power laser systems or the kinetic energy of other charged particles. This technique is under active development, but cannot provide reliable beams of sufficient quality at present.
Guiding
In all cases, the beam is steered with dipole magnets and focused with quadrupole magnets. With the end goal of reaching the desired position and beam spot size in the experiment.
Many phenomena in astrophysics are attributed to particle beams of various kinds. Perhaps of these the most iconic is the solar , due to a mildly relativistic electron beam.
Military
Though particle beams are perhaps most famously employed as directed-energy weapon systems in science fiction, the U.S. Advanced Research Projects Agency started work on particle beam weapons in 1958. The general idea of such weaponry is to hit a target object with a stream of accelerated particles with high kinetic energy, which is then transferred to the molecules of the target. The power needed to project a high-powered beam of this kind surpasses the production capabilities of any standard battlefield powerplant, thus such weapons are not anticipated to be produced in the foreseeable future.
Proton beams such as "laser-generated proton beams" may be used as a way to generate hydrogen for the production of water on planets, such as Mars, where hydrogen is scarce and oxygen is relatively rich in the atmosphere in the form of CO2. In a Mars economy where the initial cost of water would be very high due to expense of transport from Earth to Mars, a machine that can generate hydrogen using nuclear alchemy, i.e., conversion of titanium into hydrogen ions using petawatt lasers, for example, is economical and may actually be cheaper and faster than transporting water from Earth to Mars if the technology is fully developed.
