90 unifying physics of accelerators, lasers and plasma
an inspiration and a driving force for developing higher gradients acceleration at higher (multi-tens of GHz) frequencies.
This dependence, however, eventually was not confirmed for
the practical parameters of the accelerator RF pulses, where
it was observed that in these regimes the maximum gradients
appear to be rather independent of the frequency.
(09P
I*+]
FIGURE 5.25
Breakdown Kilpatrick limit (lower curve) and Wang–Loew limit
(upper curve).
5.4 Power sources
Sinusoidal power ranging from a few kW to a few MW is
needed to drive the accelerating structures. This is commonly
achieved by using RF power amplifiers such as triodes and
tetrodes (operating from a few MHz to a few hundred MHz),
inductive output tubes (suitable for CW applications, providing tens of kW at a high efficiency) and klystrons (which typically operate above a few hundred MHz) and have proven to
be the most effective power generators for accelerator applications at higher frequencies.
5.4.1 IOT — inductive output tubes
The inductive output tube, or IOT, (invented by Andrew Haeff
around 1939) is based on the principle that a toroidal cavity
surrounding an electron beam of oscillating intensity could
extract power from the beam without intercepting the beam
itself.
The oscillating EM fields carried with the beam excite the
modes found inside the toroidal cavity, which allows RF energy to be transferred from the beam to a waveguide or coaxial cable connected to the resonator via a coupling loop.
A schematic design of an IOT is shown in Fig.5.26.
an inspiration and a driving force for developing higher gradients acceleration at higher (multi-tens of GHz) frequencies.
This dependence, however, eventually was not confirmed for
the practical parameters of the accelerator RF pulses, where
it was observed that in these regimes the maximum gradients
appear to be rather independent of the frequency.
(09P
I*+]
FIGURE 5.25
Breakdown Kilpatrick limit (lower curve) and Wang–Loew limit
(upper curve).
5.4 Power sources
Sinusoidal power ranging from a few kW to a few MW is
needed to drive the accelerating structures. This is commonly
achieved by using RF power amplifiers such as triodes and
tetrodes (operating from a few MHz to a few hundred MHz),
inductive output tubes (suitable for CW applications, providing tens of kW at a high efficiency) and klystrons (which typically operate above a few hundred MHz) and have proven to
be the most effective power generators for accelerator applications at higher frequencies.
5.4.1 IOT — inductive output tubes
The inductive output tube, or IOT, (invented by Andrew Haeff
around 1939) is based on the principle that a toroidal cavity
surrounding an electron beam of oscillating intensity could
extract power from the beam without intercepting the beam
itself.
The oscillating EM fields carried with the beam excite the
modes found inside the toroidal cavity, which allows RF energy to be transferred from the beam to a waveguide or coaxial cable connected to the resonator via a coupling loop.
A schematic design of an IOT is shown in Fig.5.26.