ペニング真空計

Penning (vacuum) gauge

[目次：真空系]

冷陰極電離真空計の一種。一対の平行平板電極間(陰極)に環状電極(陽極)を置き、それらの軸に平行に磁界をかけ、電子の飛程を長くすることで低い圧力でも持続的に放電を起こさせ、中～高真空領域での圧力を測定する真空計。測定範囲は1～10^-4Pa。放電電流は圧力に比例する。堅牢で使い勝手が良いことから、電顕では油拡散ポンプ(DP)引きからスパッタイオンポンプ(SIP)引きへ切り替える制御用に使われている。

A cold-cathode ionization gauge. In the Penning (vacuum) gauge, an annular electrode (anode) is placed between a pair of parallel plate electrodes (cathode), and a magnetic field is applied parallel to their axes to lengthen the traveling distance of electrons. As a result, constant discharge occurs even at a low pressure, thus the Penning gauge can measure the pressure of the middle to high vacuum region or 1 to 10^-4Pa. The produced current is proportional to the pressure of the vacuum. For a TEM, the gauge is used for switching of the evacuation system from the diffusion pumping (DP) to the sputter ion pumping (SIP) because the gauge is robust and easy to use.

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