Scientific and Technical Aerospace Reports Volume 39 April 6, 2001

Contract(s)/Grant(s): F19628-95-C-0002
Report No.(s): AD-A384805; MIT-MS-13783; ESC-TR-99-085; Copyright; Avail: Defense Technical Information Center
(DTIC)
In situ laser cleaning is shown to be an effective tool for removal of organic contaminants on CaF2 windows. to study laser
cleaning in a controlled fashion, CaF2 substrates were pre-contaminated with 5 to 10 nm of poly(methyl methracylate),
poly(4-hydroxy styrene), poly(norbomene), and poly(beta-pinene) thin films. Irradiation of all the polymer films showed similar
trends. Initially, a high rate of material removal occurs, which depends on the chemistry of the polymer. During this period, the
material also undergoes significant bond rearrangement, forming a more tightly bound highly conjugated network. Removal of
this residual ’graphitized’ film is significantly more difficult, but can be accelerated by the presence of modest levels of oxygen.
For oxygen concentrations between 10 - 1000 ppm, the measured removal rate is approximately 3 hm/(kJ/sq cm)/ppm oxygen.
No effect on removal rate was observed as pulse energy or purge gas flow rate was varied over ranges expected to be used in practical
systems.
Author
Cleaning; Contamination; Irradiation; Lasers; Lithography
37
MECHANICAL ENGINEERING
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20010024110 Department of the Navy, Washington, DC USA
Grommet Having Metal Insert
Roush, Robert A., Inventor; Bartlett, David I., Inventor; Young, William T., Inventor; Sep. 28, 1998; 10p; In English
Patent Info.: Filed 28 Sep. 1998; US-Patent-Appl-SN-9,162,633
Report No.(s): AD-D019427; No Copyright; Avail: Defense Technical Information Center (DTIC)
The invention is directed to a grommet including a cylindrical body fabricated from rubber or synthetic rubber material. The
body has a centrally located aperture extending there through and at least one radially located aperture with a slit for easily receiving
a cable or the like. The grommet further includes a rigid insert secured to the body in the centrally located aperture. The insert
has female threads formed therein for releasably securing a tool there to remove the grommet from the ballast tank without destroying
the body of the grommet. The insert has a tubular member and an outwardly projecting circumferential flange formed on the
tubular member. The body is formed on the tubular member wherein the flange secures the insert axially with respect to the body.
Preferably, the body is fabricated from neoprene and is vulcanized to its final form.
DTIC
Reinforcement Rings; Cylindrical Bodies; Apertures; Inserts
20010025814 Sandia National Labs., Albuquerque, NM USA
Effects of Injector Conditions on the Flame Lift-Off Length of DI Diesel Sprays
Siebers, D. L.; Higgins, B. S.; Jul. 01, 2000; 27p; In English
Report No.(s): DE00-758328; SAND2000-8249; No Copyright; Avail: Department of Energy Information Bridge
The effects of injection pressure and orifice diameter on the lift-off length of a direct-injection (DI) diesel spray (defined as
the farthest upstream location of high temperature combustion) were investigated using a natural light emission imaging technique.
The lift-off length experiments were conducted in a constant-volume combustion vessel under quiescent, heavy-duty DI
diesel engine conditions using a Phillips research grade No.2 diesel fuel. The results show that natural light emission at 310 nm
provides an excellent marker of the lift-off length. At this location, natural light emission at 310 nm is dominated by OH chemiluminescence
generated by high-temperature combustion chemistry. Lift-off lengths determined from images of natural light emission
at 310 nm show that as either injection pressure (i.e., injection velocity) or orifice diameter increase, the lift-off length
increases. The observed lift-off length increase was linearly dependent on injection velocity, the same dependency as previously
noted for gas jets. The lift-off length increase with increasing orifice diameter, however, is different than the independence of liftoff
length on orifice diameter noted for gas jets An important overall observation was made by considering the lift-off length data
in conjunction with data from recent investigations of liquid-phase fuel penetration and spray development. The combined data
suggests that a systematic evolution of the relationship and interaction between various processes in a DI diesel spray has been
occurring over time, as injection pressures have been increased and orifice diameters reduced as part of efforts to meet emissions
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