H− temperature measurements by a slit diagnostic technique

Autor:	Paul Allison, Carl Geisik, H. Vernon Smith, Joseph D. Sherman
Rok vydání:	1991
Předmět:	Transverse plane Materials science Penning ionization Electric field Thermal emittance Plasma diagnostics Atomic physics Instrumentation Beam (structure) Ion source Ion
Zdroj:	Review of Scientific Instruments. 62:2314-2317
ISSN:	1089-7623 0034-6748
DOI:	10.1063/1.1142291
Popis:	H− ion beams are extracted at 5–25 kV from a long, narrow slit on a Penning surface‐plasma source (the 8X source). The extraction geometry produces negligible transverse electric fields (focusing effects) along the slit length. Therefore, the ion angular spread reflects the distribution of ion energies at the plasma surface. The angular distributions are measured with an electric‐sweep emittance scanner whose slits are oriented normal to the long dimension of the emission slit. The nearly Maxwellian angular distributions measured over the central portions of the ribbon beam give kTH− of 0.1–0.2 eV for a 2‐A dc discharge and 0.8–1.0 eV for 350–500 A pulsed discharges. This diagnostic technique has sufficient position resolution to allow measurement of the kTH− spatial distributions. It also allows study of the kTH− dependencies on ion source parameters (e.g., increasing the H2 gas flow lowers kTH−).
Databáze:	OpenAIRE
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