A sharply focused beam of electrons ( a cathode ray ) is generated by the electron gun at ground potential and accelerated by the anode ( the first dynode of the electron multiplier ) around the gun at a high positive voltage ( approx . + 1500 V ).
32.
Farnsworth addressed this problem with the invention of an " electron multiplier " ( not to be confused with contemporary electron multipliers ), a device that increased the number of electrons in a circuit by generating " secondary emissions " of electrons from a pair of opposed surfaces, thus amplifying the electrical signal.
33.
Farnsworth addressed this problem with the invention of an " electron multiplier " ( not to be confused with contemporary electron multipliers ), a device that increased the number of electrons in a circuit by generating " secondary emissions " of electrons from a pair of opposed surfaces, thus amplifying the electrical signal.
34.
Faraday cups are not as sensitive as electron multiplier detectors, but are highly regarded for accuracy because of the direct relation between the measured current and number of ions . This device is considered a universal charge detector because of its independence from the energy, mass, chemistry, etc . of the analyte.
35.
The newly formed " product ions " flow into the mass spectrometer chamber, which contains a second quadrupole mass filter, and an electron multiplier detector, which are used to separate the ions by their mass-to-charge ratios ( m / z ) and measure the count rates of the ions in the desired m / z range.
36.
For decades, electron-tube designers tried to augment amplifying tubes with electron multipliers in order to increase gain, but these suffered from short life because the material used for the dynodes " poisoned " the tube's hot cathode . ( For instance, the interesting RCA 1630 secondary-emission tube was marketed, but did not last . ) However, eventually, Philips of the Netherlands developed the EFP60 tube that had a satisfactory lifetime, and was used in at least one product, a laboratory pulse generator.
