@Article{UedaSouzMariPich:2018:OvShOv,
author = "Ueda, M{\'a}rio and Souza, G. B. de and Mariano, Samantha de
F{\'a}tima Magalh{\~a}es and Pichon, L.",
affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)} and
{Universidade Estadual de Ponta Grossa} and {Instituto Nacional de
Pesquisas Espaciais (INPE)} and {Institut Pprime - CNRS
-Universite de Poitiers-ENSM}",
title = "Overcoming sheaths overlapping in a small diameter metallic tube
with one end closed and using a high density plasma from a high
power pulsed hollow cathode discharge",
journal = "AIP Advances",
year = "2018",
volume = "8",
number = "1",
pages = "e085103",
month = "Aug.",
abstract = "High voltage sheaths are formed when plasmas are produced by
application of high negative voltage pulses to conductive supports
or components, as in Plasma Immersion Ion Implantation (PIII)
treatments of materials surfaces. For parts with concave shape, as
inside metal tubes, these sheaths behave quite differently
according to the tube configuration and size, as well as, PIII
treatment pressure of operation and pulsing parameters. In this
work, an SS304 tube of 1.1 cm internal diameter and 20 cm length
was pulsed typically at -0.5 to -2.6 kV, 20 µs pulse length, 500
Hz repetition rate, nitrogen pressure of 5x10-2 mbar and with one
side closed configuration. Different currents (between 10 and 30
A) were used to produce plasmas with sheaths that overlapped or
not, depending on the currents used. To study these sheath
behaviors, a simple plasma diagnostic technique based on a
bi-dimensional mapping of the deposition of sputtered materials
and by etching via the plasma on a Si wafer target surface, both
coming out from the tube, was used. This mapping showed clearly
the border line situation between overlapping and non-overlapping
sheaths in that small tube which allowed to estimate the plasma
density to be around 1011 cm-3 at such a sheath condition, as
previously anticipated by Sheridan. Above that border condition,
nitrogen PIII was successfully obtained in such a small tube of
SS304, producing TiN and Ti2N in samples of Ti6Al4V placed inside
the tube, when temperatures higher than 800\◦C were reached
there. Below the border, no significant uptake of nitrogen was
possible. Using this type of experimental set-up, it is now
possible to explore different hollow cathode behaviors, efficient
or high temperature (above 800\◦C) PIII conditions and also
new utilizations of the plasma ejected from the tube.",
doi = "10.1063/1.5040588",
url = "http://dx.doi.org/10.1063/1.5040588",
issn = "2158-3226",
language = "en",
targetfile = "ueda_overcoming.pdf",
urlaccessdate = "27 abr. 2024"
}