Microwave-assisted selective demolition of concrete - Microwave-Assisted Concrete Technology: Production, Demolition and Recycling - page 100

Figure 3.10 Microwave-assisted fracturing and cutting device for hard rocks invented by
Lindroth et al. (1991) [15].
3.5.1 Microwave source and generator
The microwave source and generator are responsible for supplying the
microwave energy required. The most commonly used source of microwave
energy, primarily for reasons of efficiency, is the magnetron (Figure 3.11).
Because of mass production, magnetrons at 2.45 GHz are particularly
cheap; however, magnetrons for other frequencies are also available.
Other microwave sources are available, such as the travelling wave tube
(TWT), klystron, gyrotron, and solid-state devices. Each of these has char-
acteristics that can be exploited. For instance, at higher frequencies (e.g.,
10.6 and 18 GHz), the klystron and gyrotron are normally more efficient
than magnetrons.
3.5.2 Microwave transmission line
The microwave transmission line is responsible for transmitting the micro-
wave energy from the microwave source to the microwave applicator. This
unit comprises a variety of waveguide components used to deliver the gen-
erated microwave power to the applicator while minimising the power