Thermocouple Method for Determining the Energy Losses in a Plasma and the Distribution of the Energy Losses over the Diaphragm of the Discharge Chamber
Bolometric measurements have shown that between 10% and 80% of the energy losses in a plasma (depending upon the conditions) occur directly on the diaphragm of the Tokamak TM-2 device . In order to determine the magnitude of the losses and their distribution, we suggested using the diaphragm as a calorimeter and to record (with thermocouples) the temperature changes which develop after a discharge on various sections of the diaphragm. The distribution of the losses over the perimeter of the diaphragm can be established from the indications of thermocouples placed on the perimeter. The indications are used at a time t f at which the temperature could level out over the width of the diaphragm, but could not yet reach the equilibrium value between neighboring thermocouples (Figure 1). In order to prevent the thermocouples from being broken, they can be attached far from the inner edge of the diaphragm; for example, at a medium perimeter line. An estimate shows that under normal conditions, the heating of the usual diaphragm by an energy amounting to 20–50% of the energy introduced to the system changes the diaphragm temperature by about 1°. Such changes can be easily detected with a sensitive microvoltmeter (e.g., an M-95 instrument with a scale division of 1 μV) when one compares the readings before and after a discharge.