| 摘要 |
<p>PURPOSE:To stably obtain the quantity of electron emission to the change in an outer environment and in characteristics of an electron emitting element or the like by maintaining the quantity of the electron current indirectly measured by the calculated difference between the in-flow and out-flow currents of the electron emitting element to be constant. CONSTITUTION:A voltage V1 is applied to an electron emitting element 11 in a variable voltage circuit 14 so that a constant voltage V2 is applied to an anode 15. Then, the currents I0, I1 and I2 flow. A voltage is generated on both ends of resistances R0 and R1 by the currents I0, I1 and I2 and inputted into an amplifier 18 through amplifiers 16, 17. In the case of the resistance R0=R1=R2, the output from the amplifier 18 is to be the value corresponding to the difference between currents 10 and 11, which is the indirectly measured value of the electron emitting quantity. The voltage V1 is adjusted in such a manner that said measurement value is compared with the set value by an amplifier 19 and the difference is made to be small. Therefore, it is possible to maintain the electron emitting quantity to the desired set value without reference to the change in enviroment and in efficiency of the element 11.</p> |
