SPACE RESEARCH COORDINATION CENTER
A MASS SPECTROMETER OBSERVATION
OF
NO
IN
AN AURORAL ARC
BY
E.
C.
ZIPF,
W.
L.
BORST AND T.
M.
DONAHUE
DEPARTMENT
OF
PHYSICS
SRCC REPORT NO.
133
UNIVERSITY
OF
PITTSBURGH
PITTSBURGH. PENNSYLVANIA
27
JULY 1970
A
MASS
SPECTROM%TER
OBSERYATIOM
OF
NO
IN
Al!I
AURORAL
ARC
E.
C.
Zipf,
W.
Lo
Boret and
T.
M.
Donshue
Department
of
Physics
University
of
Pittsburgh, Pittsburgh, Pennsylvanis
15213
July
1970
On
25
March 1970 an Aerobee rocket r4.309
DA]
was
launched
+
into
a
bright
IBC
I1
The instrumentation on board included
a
quadrupole
mass
spectrometer
that
measured
the
local ion &neutral composition in the auroral
form,
separate primary and seconda,ry electron energy analyzers covering
the
nominal energy ranges
1
to
30
keV and
1
to
1000
eV respectively,
auroral arc above Fort
Churchill, Manitoba.
a
cylindrical electron probe and
a
planar total positive ion probe.
These particle experiments
were
complemented by
a
l/h-rneter
Bert
monochromator
that
scanned the
VW
auroral spectrum from
1150A
to
1500A
and four
filtered
photometers
that
measured the overhead intensity
of
the
(0,O)
first
negative band
of
B2
,
the
(1,O)
first
negative band
of
O2
,
the
(5,2)
first
positive band of
B
line
[IS
+
'D;
XSS77A1.
Fastie, 1969)
was
included to obtain information on the temporal and
structural characteristics
of
the
aurora.
+
+
and
the
auroral oxygen green
2
In addition,
an
up-down photometer (Dick and
In this paper we discuss the neutral and ion
data
obtained by
our
programmable
mass
spectrometer.
The
most important results are the
following:
of
NO
and
NO
within
the
auroral form. The molecular ions
O2
and
B2
were
conspicuously absent and comparatively large densities
of
0
were detected.
concentration exceeded the
ambient
0
concentration.
The
mass
spectrometer observed remarkably
large
concentrations
9
+
+
+
ions
In the altitude range
110
km
to
130
km
the neutral
NO
2
In previous years we have
flown
similar comprehensively instrumented
rockets into
IBC
I
and
I1
post breakup
aurpra
(Donahue et
ale,
1968;
Parkfnson
et
al,,
1970a;
Donahue et
ale,
1970; Parkinson et
al.,
1970b).
In
these displays the primary ionization and luminosity often
was
observed over
a
relatively wide altitude region
(100
-
135
km),
the prfmary electron spectrum
was
comparatively soft
(.
10
keV
electrons),
and the maximum electron density observe4 in the aurora
was
modest
(-
2
x
lo5
e/cm3). The aurora encountered on Aerobee flight
4.309
UA
was
by coqtrast
a
stable arc characterized by large fluxes of
20
-
30
.keV
primary electrons (Doering, 1970), by large local electron densities
(-
lo6
e/cm3)
and by an energy deposition confined for
the
most part
to
a
relatively narrow altitude region
(95
-
115
km).
in
Ffgure
1
where
we
show the intensity
of
the
(O,O)
first
negative band
of
N2
measured
on
the
upleg
of
the flight;
similar
results
were
obtained
for the
cl,O)
first nagative band
of
0
measurements
of
the excitation cross sections for these bands (Borst
and Zipf 1970a, 1970b), the total ionization cross sections for
N2,
O2
and
0
(Kieffer and
Dum,
1966),
and our in situ opticalmeasurements,
we
estimate that the
maximum
ionization
rate
in this arc
was
approximately
2
x
105
ion pairs/cm3sec
at
102
kmo
This
is
illustrated
f
+
Using
recent laboratory
2O
In an earlier auroral experiment
(4,217
UA;
Donahue
et
ale,
1970)
++
we
observed an unusually large
NO
/O
spectrometer.
(1968)
breakup aurora,
we
supposed that
NO
ratio
with
a
single mode ion
mass
2
Similar results have been obtained by Swider
et
al.,
In
order to explain this observation, which
was
made in
a
post-
+
ions were produced by rapid charge
transfer
2