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Title: Atmospheric Pressure Plasma Jet


1
Atmospheric Pressure Plasma Jet
  • Abstract authors H.W. Herrmann, L. Rosacha
  • Los Alamos National Laboratory
  • Los Alamos, NW 87544
  • Presented by Zhenwei Hou

2
What is Atmospheric Pressure Plasma Jet(APPJ)
APPJ a non-thermal, glow-discharge plasma
operating at atmospheric pressure. The
non-thermal plasma (NTP) generates highly
reactive ions, electrons and free radicals.
The reactive species are directed onto a surface
where the desired chemistry occurs. The
electrons are quite hot, however the overall
gas temperature remains quite cold, typically
50-300 C.
Source Louis Rosocha, Non-Thermal Reactor
Technology for Control of Atmospheric Emissions,
3
APPJ Advantage
Non expensive vacuum equipment is required. Non
constraint is related to a chamber based
process. Thin film processes with high rate is
possible.
The rectangular box in the lower right corner
represents the domain for vacuum processing.
The larger box represents the domain
constraints for atmospheric pressure plasma
processing. The larger box also contains much
of the process domain represented for
vacuum-based plasma processing.
Source http//www.lanl.gov/partnerships/pdf/licen
se/appj_2.pdf
4
APPJ Applications
Clean steel draw roll used to produce nylon.
Remove Photoresist from silicon wafer. Etch
polyimide, tungsten, tantalum, silicon and
SiO2. Make Teflon wettable so that it can bond
with other materials. Remove graffiti.
Decontaminated surface exposed to chemical or
biological warefare agents or surfaces
containing radioactive materials.
Source http//www.lanl.gov/partnerships/pdf/licen
se/appj_2.pdf
5
APPJ Devices
Feed gas Inert carrier gas He reactive gas O2,
H2O, CF4. Frequency 13.56 MHz Power 300 W
The low temperature plasma is generated by the
electrical field between the electrodes. The
plasma boosters other atoms or molecules into the
their metastable states. Unlike the plasma, the
metastables can survive in the air for a few
tenths of a second. The long-life metastables
have enough time to reach and react with their
targets.
Source www.emtd.lanl.gov/TD/Treatment/NonthermalP
lasmaTreatment.html
6
APPJ Process
Feed gas
Be activated
Closely spaced electrodes powered 300W at 13.56MHz
electron temp 2eV electron density 1011 cm-3
Plasma
feed gas becomes excited, dissociated and ionized
Metastable Species radicals
Temp 50-300 C
Onto the surface
Source http//www-p24.lanl.gov/
7
Cleaning with APPJ
APPJ Plasma excites the air or oxygen feed gas
and generates reactive oxygen species. The
reactive oxygen species burn many organic
materials with a release of H2O and CO2.
Source http//www.lanl.gov/p/pdfs/papp_appj.pdf
8
Deposition of SiO2 with an APPJ
PROCESS PARAMETERS Carrier gas He, 757.2
Torr Reactive materials O2 2.8 Torr TEOS
(Tetraethoxysilane), 7.1 mTorr Substrate
Si(100), 115 C (at the back surface) Total flow
rate 49.4 l/min (at 25 C and 760
Torr) Distance 1.7cm Power 280 W RF
QUALITY PERFORMANCE OF SILICON DIOXIDE
FILM The refractive index 1.43 to
1.47 (measured by ellipsometry) The dielectric
constant 3.8073
Source S.E. Babayan, R.F.Hicks et al, Deposition
of silicon dioxide with an atmospheric-pressure
plasma jet, Plasma Sources Sci, Technol. 7(1998)
286-288
9
APPJ SiO2 Deposition
The deposition rate increases with the power
from 180 to 500W. The process is limited by
the flux of reactive species in the plasma.
The highest recorded deposition rate is 3020
A/min at TEOS partial pressure of 0.2 Torr and
RF power of 400 W. The deposition rate
decreases with increasing sample temperature
(Arrhenius relationship).
The transmission infrared absorption spectra of
the SiO2 film is indistinguishable from the that
of SiO2 produced by the thermal oxidation of a
silicon wafer at 900 C. The dielectric
constants are varied from 5.2 for films grown
below 150 C to 3.8 for films grown at 350 C.
10
Sterilization with APPJ
The feed gas (air) is pumped into the chamber
and ionized by the metastable Helium. The
plasma power density 50 100 mW/cm3. The
kinetic temperature of electron 1- 5 eV. The
bacterium sample 3 x 107/ml of E. coli
bacteria. The outer membrane of the cells is
punctured during its exposure to the plasma.
The punctured cells become very vulnerable to the
surrounding plasma environment.
E. coli bacterium in the untreated control sample
E. coli bacterium subjected to 30 seconds
exposure to the plasma.
Source M. Laroussi, M. Chad et al., Images of
Biological Samples undergoing sterilization by a
glow discharge at atmospheric pressure, IEEE
Transactions on Plasma Science v27. N1 1999,
P34-35.
11
Decontamination of Chemical Biological Warfare
(CBW) Agents with APPJ
The use of CBW agents in either a domestic
terrorist attack or military conflict is a
growing threat. Biological warefare agents
consist of Spore forming bacteria
(Anthrax) Vegetative bacteria (Plague, E.
coli) Viruses (Small Pox, Yellow Fever) Biotoxins
(Ricin, Botox) Toxic chemical warfare agents
consist of Blister agents (Mustards,
Lewisite) Nerve agents V agents(VX), G agents
(Tabun, Sarin, Soman) Choking agents
(phosgene) Blood agents (Hydrogen Cyanide)
A U. S. Air Force Armstrong Laboratory report
on BW countermeasures concluded that the
pulsed corona discharge reactor may have
potential as a countermeasure, but its ability
to destroy appropriate agents remains to be
demonstrated. APPJ has greater potential and
less risk than corona plasma discharge.
Source H.W. Herrmann, I. Henins, J. Park et
al., Decontamination of Chemical and Biological
Warefare (CBW) Agents Using an Atmospheric
Pressure Plasma Jet, Physics of Plasmas 6,
2284-2289 (1999)
12
CBW Decon with APPJ
Biological Decon
Chemical Decom
PROCESS PARAMETERS Sample temp 175 C Exposure
time 30 s Hot gas power 200 W Plasma power 300
W Distance 0.5 cm He flow 92 slpm O2 flow0.72
slpm Electrode gap0.16cm Hot gas is used as a
control.
Mustard simulant
Dried BG spores
Dried BG spores
VX simulant
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