13 research outputs found
Enhancing surface production of negative ions using nitrogen doped diamond in a deuterium plasma
The production of negative ions is of significant interest for applications
including mass spectrometry, particle acceleration, material surface
processing, and neutral beam injection for magnetic confinement fusion. Methods
to improve the efficiency of the surface production of negative ions, without
the use of low work function metals, are of interest for mitigating the complex
engineering challenges these materials introduce. In this study we investigate
the production of negative ions by doping diamond with nitrogen. Negatively
biased ( V or V), nitrogen doped micro-crystalline diamond films
are introduced to a low pressure deuterium plasma (helicon source operated in
capacitive mode, 2 Pa, 26 W) and negative ion energy distribution functions
(NIEDFs) are measured via mass spectrometry with respect to the surface
temperature (30C to 750C) and dopant concentration. The
results suggest that nitrogen doping has little influence on the yield when the
sample is biased at V, but when a relatively small bias voltage of
V is applied the yield is increased by a factor of 2 above that of un-doped
diamond when its temperature reaches 550C. The doping of diamond with
nitrogen is a new method for controlling the surface production of negative
ions, which continues to be of significant interest for a wide variety of
practical applications