Low direct current calibration sources based on the nuclear electric batteries with direct charge collection

In the paper miniature calibration sources of low direct current (CSC) equal to 10-5 - 10-10 A are discussed. It has been shown that the current sources, designed on the base of the method of direct collection of charged particles produced during α- and β-radionuclides decay, can be used as build-in current sources for calibration of low current meters (10-8 - 10-17 A) of different purpose, but they are especially effective in calibration of automatic electrometry and dosimetry instruments working in the hard radiation and climatic conditions. Comparisons are given of the CSC with well known low current sources, based on the ionization chamber use. The possibility is analysed of the direct application of a nuclear battery as the CSC. Technological difficulties are considered of fabrication of the CSC and requirements are listed to the radiation sources used in the CSC. Factors are listed stabilizing current of the CSC and determining their continious work resource. Possibility of principle is shown of creation the CSC with nominal current value from 10-14 to 10-10 A and with current fluctuation in the limits of 1% and years unstability of 1 - 3% and with the work resource of tenth of years. The results are given of testing of experimental CSC with nominal current value from 2x10-11 to 4x10-15 A