加速電圧

accelerating voltage

[目次：装置]

電子銃を構成する陰極と陽極の間の電位差のこと。SEMにおける加速電圧(accelerating voltage)の範囲は約500 Vから約30 kVが一般的である。電子源（陰極）から放たれた電子は、この電圧によって加速され、電子銃の出口となる孔の開いた電極（陽極）から照射レンズ系、偏向系を通り試料に入射する。加速電圧と試料への入射電圧は等しいことが多いが試料に電圧を印加した場合は異なる。試料に電圧を印加した場合、入射電圧は加速電圧から試料電圧を差し引いたものとなる。入射電子の試料への侵入深さは、加速電圧ではなく入射電圧によって決まる。

The accelerating voltage means the potential difference between the cathode and anode which constitute the electron gun. The accelerating voltage for SEM ranges typically from about 500 V to about 30 kV. Electrons emitted from the electron source (cathode) are accelerated by this voltage and pass through a holey electrode (anode) or the exit of the electron gun and are incident on a specimen through the illumination lens system and the deflection system.
In many cases, the accelerating voltage is equal to the incident (landing) voltage to the specimen. When an extra voltage is applied to the specimen, the landing voltage is different from the accelerating voltage. In this case, the landing voltage is the accelerating voltage minus the specimen voltage. The penetration depth of the incident electrons into the specimen is determined by the landing voltage, not by the accelerating voltage.