Reflectometry applied to the measurement of density profiles on fusion plasmas has been subject to many recent developments. After a brief reminder of the principles of reflectometry, the theoretical accuracy of reflectometry measurements is discussed. The main difficulties limiting the performance, namely the plasma fluctuations and the quality of the transmission lines, are analysed. The different techniques used for reflectometry are then presented grouped into three different categories, depending on the frequency spectrum of the probing wave: single frequency, few discrete frequencies, or broad spectrum. The present status and achievements of actual implementations of these techniques are demonstrated, with an analysis of their respective limitations and merits, as well as foreseen developments. Finally, a discussion of the various reflectometry techniques is made, in particular their ability to cope with plasma fluctuations and complex transmission lines, in view of the application to next step machines and very severe environments.
核融合プラズマにおける密度分布の測定に適用される反射測定法は、近年多くの発展を遂げてきた。反射測定法の原理を簡単に述べた後、理論的な精度について考察する。性能を制限する主な困難、すなわちプラズマの揺らぎと伝送路の品質について分析する。次に、反射測定法に用いられる様々な技術を、探査波の周波数スペクトルに応じて、単一周波数、少数の離散周波数、広帯域の3つのカテゴリーに分類して提示する。これらの技術の実際の実装における現状と成果を示し、それぞれの限界と利点、ならびに今後の発展の見通しについて分析する。最後に、様々な反射測定技術の比較考察を行い、特に次世代装置や極めて過酷な環境への応用を視野に入れた場合の、プラズマの揺らぎや複雑な伝送路への対応能力に焦点を当てて議論する。