English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

A new method involving mass spectrometry and modelling is described in thiswork, which may highlight the production mechanisms of negative ions on surfacein low pressure plasmas. Positive hydrogen ions from plasma impact a samplewhich is biased negatively with respect to the plasma potential. Negative ions(NI) are produced on the surface through the ionization of sputtered andbackscattered particles and detected according to their energy and mass by amass spectrometer placed in front of the sample. The shape of the measurednegative-ion energy distribution function (NIEDF) strongly differs from theNIEDF of the ions emitted by the sample because of the limited acceptance angleof the mass spectrometer. The reconstruction method proposed here allows tocompute the distribution function in energy and angle (NIEADF) of thenegative-ions emitted by the sample based on the NIEDF measurements atdifferent tilt angles of the sample. The reconstruction algorithm does notdepend on the NI surface production mechanism, so it can be applied to any typeof surface and/or NI. The NIEADFs for HOPG (Highly Oriented Pyrolitic Graphite)and Gadolinium (low work-function metal) are presented and compared with theSRIM modelling. HOPG and Gd show comparable integrated NI yields, however thekey differences in mechanisms of NI production can be identified. While for Gdthe major process is backscattering of ions with the peak of NIEDF at 36 eV, incase of HOPG the sputtering contribution due to adsorbed H on the surface isalso important and the NIEDF peak is found at 5 eV.

Reconstruction of energy and angle distribution function of surface-emitted negative ions in hydrogen plasmas using mass spectrometry