Code UG Weekly Notes 10-10-01

Physical Sciences Division
Weekly Highlights for Week Ending 10/10/2001

*** Indicates item is appropriate for the HQ senior staff and may appear
on the OBPR Web site: http://spaceresearch.nasa.gov

GENERAL

*** WOLFGANG KETTERLE WINS 2001 NOBEL PRIZE FOR PHYSICS: Fundamental
Physics principal investigator Wolfgang Ketterle of MIT has been named
one of three recipients of the 2001 Nobel prize in physics. Along with
Eric Cornell and Carl Wieman of JILA and NIST, Ketterle was cited "…for
the achievement of Bose-Einstein condensation in dilute gases of alkali
atoms, and for early fundamental studies of the properties of the condensates."
NASA and JPL join with the physics community in congratulating Wolfgang
on this well-deserved award. http://www.nobelprizes.com/

COMBUSTION INVESTIGATOR INDUCTED INTO US NATIONAL ACADEMY OF ENGINEERING:
Combustion co-I Prof. Felix Weinberg was inducted into the US National
Academy of Engineering last week. He is co-I on a ground-based combustion
grant entitled, "Applications of Electric Field in Microgravity Combustion";
the PI is Prof. Derek Dunn-Rankin of University of California at Irvine.
Prof. Weinberg of Imperial College has authored a book on "Optics
and Flames" and done novel research both in this diagnostics area
and in the use of electric and magnetic field effects in flames.

EDUCATION and OUTREACH

FEATURE ARTICLE ON THE MICROGRAVITY FLUID PHYSICS PROGRAM PUBLISHED IN
AEROSPACE AMERICA: "Going with the flow: Microgravity fluid physics"
is the title of an article published in the October 2001 issue of the
AIAA magazine, Aerospace America, Vol. 39, No. 10, pg. 20-22.. The authors
are Bhim Singh and Fred Kohl from NASA Glenn and Iwan Alexander from Case
Western Reserve University and the National Center for Microgravity Research
on Fluids and Combustion. This article is the fourth in a series that
has already featured Combustion Science, Fundamental Physics and Materials
Science. The article included descriptions of past highlights from the
Fluid Physics discipline program and the promise of future results from
the ISS.

ISS FLIGHT PROGRAM

PHYSICS OF COLLOIDS IN SPACE (PCS) ON ISS: During EXPPCS’ 84 hours of
operations over the last week, the focus of the research shifted away
from the AB6 and AB13 samples to detailed characterizations of the Colloid-Polymer
Gel and Colloidal Glass samples. Each sample was mixed and a variety of
measurements were performed to watch the beginning of the structuring
processes in these samples. These samples behave quite differently and
scatter light quite differently from the binary colloidal crystals that
have been extensively studied recently. As a result, both operators and
experiment specifiers made small mistakes in configuring some of the experiments.
Operations are now on track, but the glass sample will be remixed during
the next week to recover some lost data.

REQUIREMENTS DEFINITION REVIEW HELD AT GRC: Requirements Definition Review
(RDR) for the Fluid Physics flight definition experiment "Microscale
Hydrodynamics near Moving Contact Lines" was held at GRC on 10/2/01.
The moving contact line is a key problem in the understanding and predictive
modeling of a host of technologically important processes. Some of these
occur in a terrestrial environment; such as oil recovery, the manufacturing
of advanced composite materials, and chemical and biological processing
in microfluidic devices employing new "Lab-on-a-Chip" technologies.
Dr. Gerald Pitalo, Fluid Physics Enterprise Scientist at NASA HQ Code
U convened the review. Prof. Stephen Garoff (Carnegie Mellon) is the PI
and Dr. Enrique Rame (NCMRFC/GRC) is teh Co-I. This experiment is designed
for ISS. Dr. David Jacqmin (GRC) is the Project Scientist and Amy Jankovsky
(GRC) is the Project Manager.

SCIENCE HIGHLIGHTS

COMBUSTION SCIENCE:

UNSTEADY MULTIDIMENSIONAL NUMERICAL SIMULATIONS OF FLAME-VORTEX INTERACTIONS
IN MICROGRAVITY: This research, being led by Dr. G. Patnaik at the Naval
Research Labs, studies flame-vortex interactions (FVI), which play an
important role in the propagation and extinguishment of turbulent flames.
Most studies of FVI ignore the effects of gravity, however, recent microgravity
experiments show that a reduction in gravity can significantly alter the
structure of the flame produced by the FVI. There are a number of plausible
and often conflicting explanations for these differences. A richer understanding
of FVI is possible if the numerical simulations closely complement laboratory
experiments. In this study, detailed time-dependent, multi-dimensional
numerical simulations are used to investigate the relative importance
of the processes occurring in the flame-vortex interactions in normal
and reduced gravity. Towards that end, a flame from a small kernel at
one end of a tube filled with the premixed lean methane-air mixture is
initiated. The flame begins to propagate toward the closed end. At a certain
time, a vortex of sufficient strength is created within the tube and moves
towards the oncoming flame. The ensuing interaction causes a pocket of
flame to be pinched off. This calculation has been carried out for -1g,
zero g and +1g (-1g corresponds to downward propagation, +1g to upward).
It is clear that gravity affects the flame shape even prior to the interaction
with the vortex. The interaction itself in the three cases has both differences
and similarities. Several interesting questions arise: Are the differences
due to the variations in flame shape, or are they due to gravity, though
gravity itself has determined the flame shape? The influence of flame
shape and gravity needs to be sorted out in order to understand what the
basic role of buoyancy is.

DETERMINATION OF COOL FLAME QUENCHING DISTANCES AT MICROGRAVITY: This
research is being conducted by Dr. H. Pearlman from the University of
Southern California. Quenching due to conduction heat loss has received
much attention as it pertains to hot flames, yet little attention has
been given to cool flame quenching. It is generally presumed that cool
flame quenching distances are larger than those associated with hot flames,
however this presumption has never been put to a rigorous test. This study
has two objectives, (1) to isolate the role of conduction heat loss on
cool flame quenching, and (2) to determine if cool flames can propagate
through hot flame quenching distances (and vice versa) for conditions
that support both flame types. To wards this end, a new vessel for studying
cool flame quenching distances has been fabricated. It consists of a gradually
tapered quartz tube. The near future plan is to first use this vessel
in the lab for measuring quenching distances associated with cool flames
of butane and propane (diluted) with oxygen, and subsequently, compare
the results to experiments on the KC-135 airplane.

FLUID PHYSICS:

THEORY PROPOSED TO EXPLAIN VOIDS IN DUSTY PLASMAS: Fluid Physics PI Prof.
J. Goree (U. of Iowa) and colleagues have proposed a theory describing
the formation of voids in dusty plasmas, which are laboratory plasmas
containing micron-scale particles. A dust void, i.e., the dust-free region
in a dusty plasma, results from the balance of the electrostatic and plasma
(such as the ion drag) forces acting on a dust particle. The properties
of dust voids depend on the ratio of the void size to the mean free path
of plasma ions colliding with neutral species of a weakly ionized plasma.
For many plasma-processing and plasma-crystal experiments, the size of
the void is much larger than the ion-neutral mean free path. The researchers
present theory and numerical results for such a collisional case including
the situations in which the plasma is quasineutral in the void region
or the plasma quasineutrality is violated, as well as the case in which
the ion ram pressure is insignificant. Dusty plasma research is a rapidly
growing field with applications ranging from fundamental studies of freezing
and melting phase transitions to the formation of stars to the control
of contamination in the processing of semiconductor devices. This work
is reported in the following paper:

V.N. Tsytovich, S.V. Vladimirov, G.E. Morfill, and J. Goree,"Theory
of collision-dominated dust voids in plasmas," Physical Review E
Vol. 63, pp. 056609-1 056609-11 2001.

FUNDAMENTAL PHYSICS:

SUMO PAPER PRESENTED AT RELATIVITY CONFERENCE: John Lipa of Stanford
University reports that Dr. J. Nissen presented an invited talk on the
SUMO flight experiment program at the 2nd CPT and Lorentz Invariance Conference
in Bloomington, Indiana in August. The conference focused on potential
departures from the Standard Model of matter, some of which can be tested
with precision clocks like SUMO. It is expected that SUMO will be able
to make a number of unique contributions in this area, in addition to
the more direct tests of relativity theory initially planned for the experiment.
Calculations on SUMO’s sensitivities are in progress at Indiana University.

RICE GROUP PUBLISHES PAPER IN PHYSICAL REVIEW: The authors describe their
observations of a light-induced frequency shift in the single-photonphotoassociative
spectra of magnetically trapped, quantum degenerate Li-7. The shift is
a manifestation of the coupling between the threshold continuum scattering
states and discrete bound levels in the excited-state molecular potential
induced by the photoassociation laser. The frequency shift is observed
to be linear in the laser intensity with a measured proportionality constant
that is in good agreement with theoretical predictions. The frequency
shift has important implications for a scheme to alter the interactions
between atoms in a Bose-Einstein condensate using photoassociation resonances.

Randy Hulet of Rice University reports that the following paper has been
accepted for publication in Physical Review A: "Photoassociative
Frequency Shift in a Quantum Degenerate Gas", by J. M. Gerton, B.
J. Frew, and R. G. Hulet

UPCOMING EVENTS

Additional meetings and symposia can be found at: http://microgravity.grc.nasa.gov/ugml/ugmltext.htm

September 19-20, 2001 Face-To-Face MRT Meeting, JSC

October 14-18, 2001, 17th Interdisciplinary Laser Science Conference,
Long Beach Convention Center, Long Beach, CA

October 18, 2001, TeleConference MRT Meeting, 10:00am – 02:00pm CST

November 15, 2001, TeleConference MRT Meeting, 10:00am – 02:00pm CST

December 12-13, 2001, Face-To-Face MRT Meeting, MSFC