@PhDThesis{Araújo:2018:TrCaRe,
author = "Ara{\'u}jo, Michel Felipe Lima de",
title = "Tratamento de cavidades reentrantes de ni{\'o}bio via
implanta{\c{c}}{\~a}o i{\^o}nica por imers{\~a}o em plasma de
nitrog{\^e}nio para o detector de ondas gravitacionais Mario
Schenberg",
school = "Instituto Nacional de Pesquisas Espaciais (INPE)",
year = "2018",
address = "S{\~a}o Jos{\'e} dos Campos",
month = "2018-07-26",
keywords = "cavidades supercondutoras, implanta{\c{c}}{\~a}o i{\^o}nica,
fator de qualidade, uperconducting cavities, ion implantation,
quality factor.",
abstract = "Cavidades supercondutoras de ni{\'o}bio, usadas como parte dos
transdutores param{\'e}tricos do detector de ondas gravitacionais
Mario Schenberg, foram tratadas pelo m{\'e}todo de
implanta{\c{c}}{\~a}o i{\^o}nica por imers{\~a}o em plasma em
alta temperatura (3IP-AT). O objetivo final {\'e} o de aumentar
os respectivos valores dos fatores de qualidade el{\'e}tricos
(Qe) implicando no aumento da sensibilidade do detector.
Inicialmente, as implanta{\c{c}}{\~o}es se deram em amostras de
ni{\'o}bio sob distintas condi{\c{c}}{\~o}es experimentais,
variando-se par{\^a}metros como: temperatura das amostras, tempo
de tratamento, energia/dura{\c{c}}{\~a}o/frequ{\^e}ncia dos
pulsos de alta tens{\~a}o negativa. Procedimentos de limpeza da
superf{\'{\i}}cie p{\'o}s-implanta{\c{c}}{\~a}o envolvendo
descarga luminescente de arg{\^o}nio e/ou ataques
qu{\'{\i}}micos foram avaliados quanto a sua efetividade para
eliminar impurezas das amostras. Elas foram caracterizadas quanto
{\`a} morfologia, forma{\c{c}}{\~a}o de fases e perfil de
concentra{\c{c}}{\~a}o at{\^o}mica dos elementos presentes na
superf{\'{\i}}cie. Tais caracteriza{\c{c}}{\~o}es foram
imprescind{\'{\i}}veis para nortear a escolha de par{\^a}metros
da implanta{\c{c}}{\~a}o de nitrog{\^e}nio para serem
replicados nas cavidades ressonantes. Buscou-se formar camada
supercondutora de nitreto de ni{\'o}bio na superf{\'{\i}}cie do
metal, mas a utiliza{\c{c}}{\~a}o do 3IP-AT corroborou
tamb{\'e}m para {\`a} co-forma{\c{c}}{\~a}o de fases n{\~a}o
supercondutoras. Entretanto, foram obtidos aumentos nos valores de
Qe de at{\'e} duas ordens de grandeza para cavidades implantadas
em compara{\c{c}}{\~a}o com as que n{\~a}o sofreram
implanta{\c{c}}{\~a}o i{\^o}nica de nitrog{\^e}nio. Notouse
que os maiores valores de Qe foram alcan{\c{c}}ados para
par{\^a}metros de tratamento que propiciassem a
forma{\c{c}}{\~a}o da fase Nb-N, em que o nitrog{\^e}nio, em
baixas concentra{\c{c}}{\~o}es at{\^o}micas, encontra-se
dissolvido no ni{\'o}bio, formando solu{\c{c}}{\~a}o
s{\'o}lida e ocupando posi{\c{c}}{\~a}o intersticial na rede
cristalina. Esta pesquisa corrobora hip{\'o}teses levantadas por
estudos recentes envolvendo o tratamento de cavidades de
ni{\'o}bio utilizadas em aceleradores de part{\'{\i}}culas.
ABSTRACT: Niobium superconducting cavities, used as part of the
parametric transducers for Mario Schenberg gravitational wave
detector, were treated via high temperature nitrogen plasma
immersion ion implantation (3IPAT). The main objective is to
increase the respective values of the electrical quality factors
(Qe) - implying the increase of the sensitivity of the detector.
Initially, the implantations were performed in niobium samples
under different experimental conditions, varying some parameters
such as: sample temperature, treatment time, energy / duration /
frequency of negative high voltage pulses. Post-implantation
surface cleaning procedures which involves glow argon discharge
and / or chemical attacks were evaluated for their effectiveness
in removing impurities from samples. They were characterized by
means of their morphology, phase formation and the atomic
concentration profiles of the elements present on the very near
surfaces. Such characterizations were essential to guide the
choice of nitrogen implantation parameters to be replicated in the
resonant cavities. As a first step, it was sought to form niobium
nitride superconducting layer on the metal surface, but the 3IP-AT
process proved to be ineffective for this purpose due to the
coformation of undesirable non-superconducting phase formation.
Nevertheless, increases in Qe values of up to two orders of
magnitude were obtained for implanted cavities in comparison with
untreated ones. It was observed that the higher Qe-factors were
reached for treatment parameters that favored the formation of the
Nb-N phase, in which nitrogen, in low atomic concentrations, is
dissolved in the niobium surface, forming a solid solution and
occupying an interstitial position in the crystal lattice. The
hypotheses raised in this research are in accordance with the
findings reported in recent studies for RF superconducting
cavities used in particle accelerators.",
committee = "Oliveira, Rog{\'e}rio de Moraes (presidente/orientador) and
Mello, Carina Barros (orientadora) and Mineiro, S{\'e}rgio Luiz
and Berni, Luiz Angelo",
englishtitle = "Treatment of reinforcing cavities of ni{\'o}bio via ion
implantation by immersion in plasma of nitrogen for the
gravitational waves detector Mario Schenberg",
language = "pt",
pages = "113",
ibi = "8JMKD3MGP3W34R/3RJ5JR2",
url = "http://urlib.net/ibi/8JMKD3MGP3W34R/3RJ5JR2",
targetfile = "publicacao.pdf",
urlaccessdate = "27 abr. 2024"
}