7 Design and Principles of Linear Accelerators and Colliders
307
Technological developments are pursued for all critical elements of the machine.
Of particular relevance are novel methods of alignment in the micron range and
stabilisation in the nano-meter range. Power reductions studies with high efficiency
klystrons and permanent magnets are important R&D activities. Civil engineering
and infrastructure studies have been done to establish the cost and schedule of the
project implementation.
Also in the case of the normal conducting technology XFELs linacs provide
important industrial lessons, so far using S or C-band technology. X-band technology is now widely considered for future compact linac installations [50].
7.3.5 Common Issues and Prospects
Apart from the linacs based on different RF-technologies, ILC and CLIC have
similar technology challenges for several sub-systems. This is especially so for the
beam delivery system, the machine detector interface and the civil engineering &
conventional facilities. To take advantage of the overlapping aspects of the two
studies, common working groups have been set-up and actively address common
issues for both studies including beam dynamics, low beam emittance generation,
positron generation, beam delivery system as well as cost and schedule. Issues of
low emittance beam generation, electron cloud collective instabilities, emittance
conservation studies, and beam optics for the interaction region are being tested
in test facilities supported by linear collider groups, notably in the CESR-Test
Accelerator at Cornell, FACET and SLAC, and the Accelerator Test Facility (ATF2)
at KEK [51–53].
The 250 GeV ILC project is currently being evaluated for implementation in
Japan. During 2018 one is expecting that Japan can conclude this evaluation which
will determine if the project will move forward towards realisation. Such a machine
could start operation in the early 2030s. The CLIC collaboration will submit a
Project Implementation Plan by the end of year, describing a project that could come
into operation after completion of the LHC programme in the mid 2030’ies.
7.4 Accelerating Structures Design and Efficiency
A. Grudiev · A. Yamamoto
In linear accelerators, beam is accelerated by accelerating structures made of a chain
of cavities (cells) fed with RF power establishing an electromagnetic field from
which part of the energy is transferred to the beam.
The efficiency of a cavity to produce an accelerating field with given RF power
is defined by the shunt impedance R. This is equivalent to Ohm’s law where the
resistance is the proportionality factor between the square of the voltage and the
307
Technological developments are pursued for all critical elements of the machine.
Of particular relevance are novel methods of alignment in the micron range and
stabilisation in the nano-meter range. Power reductions studies with high efficiency
klystrons and permanent magnets are important R&D activities. Civil engineering
and infrastructure studies have been done to establish the cost and schedule of the
project implementation.
Also in the case of the normal conducting technology XFELs linacs provide
important industrial lessons, so far using S or C-band technology. X-band technology is now widely considered for future compact linac installations [50].
7.3.5 Common Issues and Prospects
Apart from the linacs based on different RF-technologies, ILC and CLIC have
similar technology challenges for several sub-systems. This is especially so for the
beam delivery system, the machine detector interface and the civil engineering &
conventional facilities. To take advantage of the overlapping aspects of the two
studies, common working groups have been set-up and actively address common
issues for both studies including beam dynamics, low beam emittance generation,
positron generation, beam delivery system as well as cost and schedule. Issues of
low emittance beam generation, electron cloud collective instabilities, emittance
conservation studies, and beam optics for the interaction region are being tested
in test facilities supported by linear collider groups, notably in the CESR-Test
Accelerator at Cornell, FACET and SLAC, and the Accelerator Test Facility (ATF2)
at KEK [51–53].
The 250 GeV ILC project is currently being evaluated for implementation in
Japan. During 2018 one is expecting that Japan can conclude this evaluation which
will determine if the project will move forward towards realisation. Such a machine
could start operation in the early 2030s. The CLIC collaboration will submit a
Project Implementation Plan by the end of year, describing a project that could come
into operation after completion of the LHC programme in the mid 2030’ies.
7.4 Accelerating Structures Design and Efficiency
A. Grudiev · A. Yamamoto
In linear accelerators, beam is accelerated by accelerating structures made of a chain
of cavities (cells) fed with RF power establishing an electromagnetic field from
which part of the energy is transferred to the beam.
The efficiency of a cavity to produce an accelerating field with given RF power
is defined by the shunt impedance R. This is equivalent to Ohm’s law where the
resistance is the proportionality factor between the square of the voltage and the