Advanced Accelerator Concepts
Advanced Accelerator Concepts encompasses methods of beam acceleration with gradients beyond state of the art in operational facilities. This includes diagnostics methods, timing technology, special needs for injectors, beam matching, beam dynamics and development of adequate simulations. Workshops dedicated to this subject are being held in the US (alternating locations) and in Europe, mostly on Isola d’Elba. The series of Advanced Accelerator Concepts Workshops, held in the US,[44] started as an international series in 1982.[45] The European Advanced Accelerator Concepts Workshop series started in 2019.[46] Topics related to Advanced Accelerator Concepts:
- Laser Plasma Acceleration of electrons and positrons
- Laser and High-Gradient Structure-Based Acceleration
- Beam-Driven Acceleration
- Laser-Plasma Acceleration of Ions
- Beam Sources such as electron gun, Monitoring, and Control. See Accelerator physics
- Computer simulation for Accelerator Physics
- Laser technology for particle acceleration
- Electromagnetic radiation Generation
- Muon collider
According to the Inverse scattering problem, any mechanism by which a particle produces radiation (where kinetic energy of the particle is transferred to the electromagnetic field), can be inverted such that the same radiation mechanism leads to the acceleration of the particle (energy of the radiation field is transferred to kinetic energy of the particle). The opposite is also true, any acceleration mechanism can be inverted to deposit the energy of the particle into a decelerating field, like in a kinetic energy recovery system. This is the idea enabling an energy recovery linac. This principle, which is also behind the plasma or dielectric wakefield accelerrators, led to a few other interesting developments in advanced accelerator concepts:
- Cherenkov radiation led to inverse Cherenkov radiation accelerator.[47]
- Free-electron laser led to the Inverse Free-electron laser accelerator.[48]
- A laser can also be inverted to produce acceleration of electrons.[49]
At present the highest energy accelerators are all circular colliders, but both hadron accelerators and electron accelerators are running into limits. Higher energy hadron and ion cyclic accelerators will require accelerator tunnels of larger physical size due to the increased beam rigidity.
For cyclic electron accelerators, a limit on practical bend radius is placed by synchrotron radiation losses and the next generation will probably be linear accelerators 10 times the current length. An example of such a next generation electron accelerator is the proposed 40 km long International Linear Collider.
It is believed that plasma wakefield acceleration in the form of electron-beam “afterburners” and standalone laser pulsers might be able to provide dramatic increases in efficiency over RF accelerators within two to three decades. In plasma wakefield accelerators, the beam cavity is filled with a plasma (rather than vacuum). A short pulse of electrons or laser light either constitutes or immediately precedes the particles that are being accelerated. The pulse disrupts the plasma, causing the charged particles in the plasma to integrate into and move toward the rear of the bunch of particles that are being accelerated. This process transfers energy to the particle bunch, accelerating it further, and continues as long as the pulse is coherent.[38]