Accelerating voltages can be between 3 and 40 kV. When the accelerating voltage is 20–25 kV and the beam current is a few amperes, 85% of the electron's kinetic energy can be converted into thermal energy.
ɐksˈɛlɚɹˌeɪɾɪŋ vˈoʊltɪdʒᵻz kæn biː bᵻtwˌiːn θɹˈiː ænd fˈoːɹɾi kˈeɪ vˈiː. wˌɛn ðɪ ɐksˈɛlɚɹˌeɪɾɪŋ vˈoʊltɪdʒ ɪz twˈɛnti twˈɛnti fˈaɪv kˈeɪ vˈiː ænd ðə bˈiːm kˈɜːɹənt ɪz ɐ fjˈuː ˈæmpɛɹz, ˈeɪɾi fˈaɪv pɚsˈɛnt ʌvðɪ ᵻlˈɛktɹɑːnz kᵻnˈɛɾɪk ˈɛnɚdʒi kæn biː kənvˈɜːɾᵻd ˌɪntʊ θˈɜːməl ˈɛnɚdʒi.