FLUSH MOUNTED LANGMUIR PROBES IN AN OBLIQUE MAGNETIC-FIELD

Due to the high heat flux to the target plates of present day divertor tokamaks, the use of thermally robust flush mounted Langmuir probes b ecomes more and more important. The surface normal of the probe define s a direction in space which is generally neither parallel nor perpend icular to the magnetic field, and the angle between these two vectors plays an important role for the physics in front of the probe. An anal ytic description of the sheath physics in front of a target plate is p resented, and a model for the analysis of the I-V characteristics of s uch probes is derived therefrom. The model includes, on the one hand, considerably more physics than previous descriptions, and is, on the o ther hand, much simpler and more practical than numerical solutions an d simulations. Subsequently the application of this model to triple pr obes is discussed. It will become evident that flush mounted probes ca n be used as reliably as domed probes to determine the plasma paramete rs in front of the target plates. (C) 1997 American Institute of Physi cs.