Electrostatic particle accelerator
Oscillating accelerators do not have this limitation, so they can achieve higher particle energies than electrostatic machines.
There are also a number of materials analysis techniques based on electrostatic acceleration of heavy ions, including Rutherford backscattering spectrometry (RBS), particle-induced X-ray emission (PIXE), accelerator mass spectrometry (AMS), Elastic recoil detection (ERD), and others.
[5] Using a high voltage terminal kept at a static potential on the order of millions of volts, charged particles can be accelerated.
In simple language, an electrostatic generator is basically a giant capacitor (although lacking plates).
The high voltage is achieved either using the methods of Cockcroft & Walton or Van de Graaff, with the accelerators often being named after these inventors.
The practical difficulty with belts led to a different medium for physically transporting the charges: a chain of pellets.
Thus, methods such as plastic rods connected to various levers inside the terminal can branch out and be toggled remotely.
Omitting practical problems, if the platform is positively charged, it will repel the ions of the same electric polarity, accelerating them.
As E=qV, where E is the emerging energy, q is the ionic charge, and V is the terminal voltage, the maximum energy of particles accelerated in this manner is practically limited by the discharge limit of the high voltage platform, about 12 MV under ambient atmospheric conditions.
To increase the maximum acceleration energy further, the tandem concept was invented to use the same high voltage twice.
In this sense, we can see clearly that a tandem can double the maximum energy of a proton beam, whose maximum charge state is merely +1, but the advantage gained by a tandem has diminishing returns as we go to higher mass, as, for example, one might easily get a 6+ charge state of a silicon beam.
[6] It is not uncommon to make compounds in order to get anions, however, and TiH2 might be extracted as TiH− and used to produce a proton beam, because these simple, and often weakly bound chemicals, will be broken apart at the terminal stripper foil.
[7] Tandems can also be operated in terminal mode, where they function like a single-ended electrostatic accelerator, which is a more common and practical way to make beams of noble gases.
[9] One trick which has to be considered with electrostatic accelerators is that usually vacuum beam lines are made of steel.
Importantly for the physics, these inter-spaced conducting rings help to make a more uniform electric field along the accelerating column.
This beam line of glass rings is simply supported by compression at either end of the terminal.
However, some tandems may have a "U" shape, and in principle the beam can be turned to any direction with a magnetic dipole at the terminal.
A tower arrangement can be a way to save space, and also the beam line connecting to the terminal made of glass rings can take some advantage of gravity as a natural source of compression.
The electronvolt is equal to the energy a particle with a charge of 1e gains passing through a potential difference of one volt.
More powerful accelerators can produce energies in the giga electron volt (GeV) range.
