Trapped energy filters

Fig. 6.34 (a) Trapped-energy filter, (b) Surface acoustic wave (SAW) filter. 

FIGURE 4.1.13 Schematic drawing of a trapped-energy filter. 

A simple resonator is a thin disk type, electroded on its plane faces and vibrating radially, for filter applications with a center frequency ranging from 200 kHz to 1 MHz and with a bandwidth of several percent of the center frequency. For a frequency of 455 kHz, the disk diameter needs to be about 5.6mm. However, if the required frequency is higher than 10 MHz, other modes of vibration such as the thickness extensional mode are exploited, because of its smaller size. The trapped-energy type filters made from PZT ceramics have been widely used in the intermediate frequency range for applications such as the 10.7 MHz FM radio receiver and transmitter. When the trapped-energy phenomena are... 

These mass filters operate in a similar manner to Ion Trap mass filters, in that both of these filters trap ions of interest. Furthermore, both require the injection of low-energy secondary ions, similar to Quadrupole mass filters. The difference lies in the fact that FT-ICR mass filters utilize strong magnetic fields for trapping the respective ions and for recording their masses. This possibility is realized as the resonance fi equencies at which the ions trapped within the FT-ICR cavity is a function of their m/q ratio. The oscillation fi equency, termed the characteristic orbital frequency, also known as the ion cyclotron frequency cof) induced by the applied magnetic field (B ) relates to the m/ ratio via ... 

It is a good idea to incinerate filters in well-filtered furnaces in order to burn trapped impurities, reduce quantities of waste, and recover some energy. The filters from normal ventilation systems could also be dumped at a landfill. 

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