| 摘要 |
PROBLEM TO BE SOLVED: To execute normal operations, such as observation, etching or the like, and a measurement of a flow impedance in parallel, by measuring the flow impedance without changing an emission current. SOLUTION: Before operation of a device, a relation between an emission current variationΔIe and a suppressing voltage variationΔVsup in the state of an extraction voltage Vext fixed, is stored in a memory part 113 as a functionΔIe=f(ΔVsup). When measuring a flow impedance, the suppressed voltage variationΔVsup is detected at the time of changing the extraction voltage Vext byΔVext in the state of an emitter current Ie fixed. The flow impedanceΔVext/ΔIe is operated by using the voltage variationsΔVext,ΔVsup and the function taken in from the memory part 113.
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