Optical diagnostics for a high power, rf-inductively coupled plasma Page: 3 of 8
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OPTICAL DIAGNOSTICS FOR A HIGH POWER,
RF-INDUCTIVELY COUPLED PLASMA
N. S. NOGARt, G. L. KEATONt, J. E. ANDERSON AND M. TRKULA
tChemical and Laser Sciences Division, MS G738
Materials Science and Technology Division, MS G770
Los Alamos National Laboratory, Los Alamos, New Mexico, 87545
Emission spectroscopy and laser-induced fluorescence have been
used to monitor the field and tail-flame regions of a Hull-design 1
ind.ctively coupled plasma. This plasma is used for a variety of
syntheses 2,3 including SiC, TiC, BN, AiN and diamond. Temporally-
and spatially-resolved spectra of both pure Ar and Ar/gas mixtures
have been studied as a function of RF power, pressure and flow
rate. Preliminary data suggest that the system is far frcm local
In radio-frequency plasma chemical synthesis a flowing gas
passes through a super-heated plasma fireball region. Following
injection into this flow, reactant species decompose into highly
active atomic, ionic and molecular fragments. As these fragments
leave the plasma region, they cool and produce end-products of
exceptionally high purity. This process has been used tc produce
a number of fine and ultrafine materials and chemicals.
Many unanswered question persist concerning the processes and
mechanisms involved in these syntheses. Fundamental properties of
the plasma are largely unknown, including the mechanism for the
formation and transport of energetic species, temperatures energyy
distributions), scaling parameters, optimal gas mixtures and
mixing conditions. We are involved in an experimental program to
understand the chemistry end physics of plasma synthesis and rf
plasmas in general. We are applying modern spectrosrupic
techniques including emission spectroscopy and laser-induced
flucrescence (LIF). Atomic, ionic and molecular concentration-,
lifetimes and internal energy distributions are mapped out as a
fun, ion of position and phase with respect to the rf cycle.
A schematic of the Hull-design plasma, and insociat.ea apparat-u
is shown in Figure 1. We use an optical fibr: to collect emittf-d
photons, thereby facilitating spatial profiling measurements.
Temporally resolved e-ission measurement:: were performed by
scanning the gate of trie detection electronics with respec-t t, hf-
rf cycle. For I.IF n'ensurements, the pump-laser trigger was
scanned wit h a digital delay gennra or . Typical lar'
char act er i t i cs werp 8 r r, -0.1, m.7 pu 1 s< at 10 Hz, with i
bandwidth -0.5 cr.
Thy pla:.!ma was typi ra l y run at 541 kH z, wit h rlow rate:;, vx-.'
f-r diamond :yntAesI, of 1-10 STI' IJ M, and i chamber pIP;st'
bt w(nn ? and 580 tor r . lVJ power s f r most oxp r iment r: were
betwvvri ! and 15 kW.
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Nogar, N.S.; Keaton, G.L.; Anderson, J.E. & Trkula, M. Optical diagnostics for a high power, rf-inductively coupled plasma, article, January 1, 1988; New Mexico. (https://digital.library.unt.edu/ark:/67531/metadc1057153/m1/3/: accessed March 21, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.