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J. Seeman et al.
choose an RF structure such that electromagnetic fields and the beam particles are in
phase as the beam traverses each cell in the RF cavity. Much of the design work has
gone into maximizing the accelerating gradients, avoiding arcing, RF discharges,
and multipacting, to minimize the construction costs, and to make efficient use of
overall AC power. Proton and ion beams are often made in drift tube linacs (DTL)
with gradients of 2–8 MeV/m using RF frequencies of 30–400 MHz. Electron
linacs are typically made of either copper structures with 15–75 MeV/m at 3–
12 GHz or superconducting structures with 10–30 MeV/m near 1.3 GHz. Small
proton or ion linacs are used for medical therapy and patient diagnostics. Larger
proton linacs are injectors for large particle colliders or proton drivers for neutron
or neutrino production. Small electron linacs are used for electron or gamma ray
medical therapy and in industry. Large electron linacs are often injectors into GeV
energy storage rings for synchrotron radiation sources and e−/e+ colliders and as
injectors into FEL undulators.
An active area of present research is the conditioning of beams in linacs
to make them useful for high energy physics, basic energy sciences, nuclear
physics, material sciences, and technology security. These beam parameters include
the calculation and control of longitudinal and transverse wakefields (Sect. 7.5),
low emittance generation and preservation (Sect. 7.7), incoherent and coherent
synchrotron radiation effects, electron cloud effects, ion effects, energy recovery
through recirculation (Sect. 7.8), multibunch effects (Sect. 7.3), high luminosity
requirements (Sect. 7.2), final focus systems (Sect. 7.5), 2D and 3D emittance
exchanges, and beam-undulator interactions in x-ray FELs.
The use of linacs in energy frontier e+e− colliders is essential to avoid excessive
synchrotron radiation in ultrahigh energy beams. The first linear collider used the
SLAC linac called the SLC (Sect. 7.2) which provided frontier particle physics
results as well as establishing a basis to build upon for a future linear collider design.
Recent linear collider studies (Sect. 7.3) have concentrated on the ILC (1.3 GHz
Superconducting) [4] and CLIC (12 GHz normal conducting) [7]. Years of studies
and experiments have illustrated the approaching viability of these two collider
technologies.
Very attractive schemes like for example the energy recovery linacs [14] as
described in Sect. 7.8 are being developed. Recent avenues of study for far
future linacs are in the area of excited plasmas and dielectrics as structures [15,
16]. Examples are electron beam driven plasma, wakefield accelerator PWFA
that recently produced 40 GeV/m acceleration for electrons and 0.23 GeV/m for
positrons [17–20] and laser driven plasma wakefield accelerator demonstrating up
to 4.2 GeV in a 9 cm plasma [21, 22] as described in Chap. 12. Another active
research area is direct laser driven accelerating nanostructures in silicon [23, 24].
New ongoing studies in these technologies will illuminate possible future uses.
J. Seeman et al.
choose an RF structure such that electromagnetic fields and the beam particles are in
phase as the beam traverses each cell in the RF cavity. Much of the design work has
gone into maximizing the accelerating gradients, avoiding arcing, RF discharges,
and multipacting, to minimize the construction costs, and to make efficient use of
overall AC power. Proton and ion beams are often made in drift tube linacs (DTL)
with gradients of 2–8 MeV/m using RF frequencies of 30–400 MHz. Electron
linacs are typically made of either copper structures with 15–75 MeV/m at 3–
12 GHz or superconducting structures with 10–30 MeV/m near 1.3 GHz. Small
proton or ion linacs are used for medical therapy and patient diagnostics. Larger
proton linacs are injectors for large particle colliders or proton drivers for neutron
or neutrino production. Small electron linacs are used for electron or gamma ray
medical therapy and in industry. Large electron linacs are often injectors into GeV
energy storage rings for synchrotron radiation sources and e−/e+ colliders and as
injectors into FEL undulators.
An active area of present research is the conditioning of beams in linacs
to make them useful for high energy physics, basic energy sciences, nuclear
physics, material sciences, and technology security. These beam parameters include
the calculation and control of longitudinal and transverse wakefields (Sect. 7.5),
low emittance generation and preservation (Sect. 7.7), incoherent and coherent
synchrotron radiation effects, electron cloud effects, ion effects, energy recovery
through recirculation (Sect. 7.8), multibunch effects (Sect. 7.3), high luminosity
requirements (Sect. 7.2), final focus systems (Sect. 7.5), 2D and 3D emittance
exchanges, and beam-undulator interactions in x-ray FELs.
The use of linacs in energy frontier e+e− colliders is essential to avoid excessive
synchrotron radiation in ultrahigh energy beams. The first linear collider used the
SLAC linac called the SLC (Sect. 7.2) which provided frontier particle physics
results as well as establishing a basis to build upon for a future linear collider design.
Recent linear collider studies (Sect. 7.3) have concentrated on the ILC (1.3 GHz
Superconducting) [4] and CLIC (12 GHz normal conducting) [7]. Years of studies
and experiments have illustrated the approaching viability of these two collider
technologies.
Very attractive schemes like for example the energy recovery linacs [14] as
described in Sect. 7.8 are being developed. Recent avenues of study for far
future linacs are in the area of excited plasmas and dielectrics as structures [15,
16]. Examples are electron beam driven plasma, wakefield accelerator PWFA
that recently produced 40 GeV/m acceleration for electrons and 0.23 GeV/m for
positrons [17–20] and laser driven plasma wakefield accelerator demonstrating up
to 4.2 GeV in a 9 cm plasma [21, 22] as described in Chap. 12. Another active
research area is direct laser driven accelerating nanostructures in silicon [23, 24].
New ongoing studies in these technologies will illuminate possible future uses.