R. SYME, Emperors and Biography: Studies in the Historia Augusta. Oxford, Clarendon Press : Oxford University Press, 1971. VII, 306 p. Pr. £ 3.25

Wes, M. A.

doi:10.1163/156852574x00773

Cited by 1 publication

(1 citation statement)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The plasma in toroidal fusion experiments, such as tokamaks [ 5 ] or stellarators [ 6 ], is obviously very hot and rather dense, which, in principle, makes the application of probes self-forbidding. Nevertheless, in tokamaks, up to the so-called medium-size tokamaks (MST), probes have successfully been used in the outer regions of the plasma torus on the low field side (LFS), specifically in the SOL (scrape-off layer).…”

Section: Introductionmentioning

confidence: 99%

Diamond-Coated Plasma Probes for Hot and Hazardous Plasmas

Ioniţă

Schrittwieser

et al. 2020

Materials

View full text Add to dashboard Cite

Plasma probes are simple and inexpensive diagnostic tools for fast measurements of relevant plasma parameters. While in earlier times being employed mainly in relatively cold laboratory plasmas, plasma probes are now routinely used even in toroidal magnetic fusion experiments, albeit only in the edge region, i.e., the so-called scrape-off layer (SOL), where temperature and density of the plasma are lower. To further avoid overheating and other damages, in medium-size tokamak (MST) probes are inserted only momentarily by probe manipulators, with usually no more than a 0.1 s per insertion during an average MST discharge of a few seconds. However, in such hot and high-density plasmas, their usage is limited due to the strong particle fluxes onto the probes and their casing which can damage the probes by sputtering and heating and by possible chemical reactions between plasma particles and the probe material. In an attempt to make probes more resilient against these detrimental effects, we tested two graphite probe heads (i.e., probe casings with probes inserted) coated with a layer of electrically isolating ultra-nano-crystalline diamond (UNCD) in the edge plasma region of the Experimental Advanced Superconducting Tokamak (EAST) in Hefei, People’s Republic of China. The probe heads, equipped with various graphite probe pins, were inserted frequently even into the deep SOL up to a distance of 15 mm inside the last closed flux surface (LCFS) in low- and high-confinement regimes (L-mode and H-mode). Here, we concentrate on results most relevant for the ability to protect the graphite probe casings by UNCD against harmful effects from the plasma. We found that the UNCD coating also prevented almost completely the sputtering of graphite from the probe casings and thereby the subsequent risk of re-deposition on the boron nitride isolations between probe pins and probe casings by a layer of conductive graphite. After numerous insertions into the SOL, first signs of detachment of the UNCD layer were noticed.

show abstract

Section: Introductionmentioning

confidence: 99%