aslaf: detector of the direct solar lyman- alpha radiation. future alternatives v.guineva(1),...
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ASLAF: DETECTOR OF THE DIRECT SOLAR LYMAN-ALPHA RADIATION. FUTURE ALTERNATIVES
V.Guineva(1), G.Witt(2), J.Gumbel(3), M.Khaplanov(3), R.Werner(1), J.Hedin(3), S.Neichev(4), B.Kirov(5), L.Bankov(1), P.Gramatikov(4),
V.Tashev(1), K.Hauglund(6), G.Hansen(6), J.Ilstad(6), H.Wold(6)
1)Solar-Terrestrial Influences Institute (STIL), Bulgarian Academy of Sciences (BAS)Stara Zagora Department, P.O.Box 73, 6000 Stara Zagora, Bulgaria;
2)Department of Earth Sciences, The Hebrew University (HUJI), Jerusalem, Israel;
3)Atmospheric Physics Group at the Department of Meteorology (MISU), Stockholm University, S 10691 Stockholm, Sweden;
4)Space Research Institute, Bulgarian Academy of Sciences (BAS), 6 Moskovska Str., 1000 Sofia, Bulgaria;
5)Solar-Terrestrial Influences Institute (STIL), Bulgarian Academy of Sciences (BAS), Acad. Georgi Bonchev Str., Block 3, 1113 Sofia, Bulgaria;
6)Andøya Rocket Range, Andenes, Norway
Workshop “Solar influences on the ionosphere and magnetosphere”, Sozopol, Bulgaria, 7-13 June 2009
Basic scientific goal: Investigation of the processes in the mesosphere and the mesopause region by rocket measurements of the Lyman-alpha emission data.
Research purposes of ASLAF
Use of ASLAF instrument: for rocket measurements of the direct Lyman-alpha radiation penetrating in the atmosphere.
Importance of a modern L detector for rocket board measurements:
Acquiring the L altitude profile and retrieval of the real O2 concentration and temperature profiles; Possibility to study the processes in the mesosphere and low thermosphere by analysis based on the obtained profiles.
Workshop “Solar influences on the ionosphere and magnetosphere”, Sozopol, Bulgaria, 7-13 June 2009
TM
Sun radiation
Ion chamberPre-amplifier + 2-stage amplifier
Power supply U, T control
Data channels
ASLAF
Principal scheme of the L detector - ASLAF
• 2 data channels, x1 (15 nA) and x10 (1.5 nA);
• channels to monitor the power at the chamber (60V1V) and the temperature.
Workshop “Solar influences on the ionosphere and magnetosphere”, Sozopol, Bulgaria, 7-13 June 2009
ASLAF - Ionization chamber
The ionization chamber is produced by the Artech corporation.
Material: copper
Weight: 50 g
Max diameter: 30 mm
Length: 36 mm
Tubule: 32 mm
MgF2 window:• diameter = 8 mm;• sensitive to 105 – 135 nm radiation.
Quantum efficiency: 40% - 60% for 25 V – 150 V
Workshop “Solar influences on the ionosphere and magnetosphere”, Sozopol, Bulgaria, 7-13 June 2009
0
2
4
6
8
10
12
0 10 20 30 40
Pressure, mb
Cur
rent
, nA
9.6 V19.2 V28.8 V38.4 V48.0 V57.6 V67.2 V76.8 V86.4 V96.0 V
V
0
2
4
6
8
10
12
0 20 40 60 80 100
Power supply, V
Cur
rent
, nA
1 mb 3 mb 6 mb 8 mb10 mb12 mb15 mb18 mb22 mb26 mb30 mb35 mb
ASLAF - Ionization chamber
Work values chosen: P = 20 mb (86% of L are absorbed by estimation); U = 60 V; Imax = 15 nA (estimated current at the border of the atmosphere, direct Sun, Q=60%).
Current through the ionization chamber, registered at different conditions – power supply and NO pressure.
Workshop “Solar influences on the ionosphere and magnetosphere”, Sozopol, Bulgaria, 7-13 June 2009
Principal scheme of the electronic amplifier
Power supply
Filterър
Ionization chamber
+60 V
IN A1 A2
K1
K2
K3
A3
A4 A5 TD
TMOut1
TMOut2
TMT
TMV
+28 V -28 V
+6 V
-6 V
+6 V
Filter
Sections: A1 - pre-amplifier and current-voltage converter; A2 – scaling and correcting amplifier; A3 – amplifies the signal 10 times; A4 – monitors the ionization chamber power supply; A5 – monitors the temperature.
Workshop “Solar influences on the ionosphere and magnetosphere”, Sozopol, Bulgaria, 7-13 June 2009
ASLAF - Final design of the Lyman-alpha detector
The maximal dimensions of the device are 105x60x90 mm, its weight is 498 g.
Workshop “Solar influences on the ionosphere and magnetosphere”, Sozopol, Bulgaria, 7-13 June 2009
ASLAF response of the H lamp emission
-1
0
1
2
3
4
5
6
7
0 5 10 15 20
Distance to the H lamp, cm
Sig
nal,
V
Channel 15 nAChannel 1.5 nA
y = 10.005e-1.0792x
R2 = 0.9917
y = 34.616e-0.9043x
R2 = 0.9951
0.00001
0.0001
0.001
0.01
0.1
1
10
0 2 4 6 8 10 12 14
Distance to the H lamp, cm
Sig
nal,
V
Channel 1.5 nAChannel 15 nA
y = 41.652e-0.9343x
R2 = 0.997
y = 4.1073e-0.9553x
R2 = 0.9979
0.0001
0.001
0.01
0.1
1
10
0 5 10 15
Distance to the H lamp, cm
Sig
nal,
V Channel 1.5 nAChannel 15 nA
• Linear signal depending on the emission intensity is obtained from both channels;• The signal ratio can be considered 10.6 from 30 mV to 4.2 V in the channel 1.5 nA range.
ASLAF – some characteristics
Workshop “Solar influences on the ionosphere and magnetosphere”, Sozopol, Bulgaria, 7-13 June 2009
ASLAF – some characteristics
y = 0.3346x + 0.0105
R2 = 1
0
1
2
3
4
5
6
0 5 10 15 20
Current, nA
Mea
sure
d vo
ltag
e, V
Channel 15 nA
y = 0.3377x + 0.0057
R2 = 0.9987
y = 3.608x + 0.0579
R2 = 0.9952
00.5
11.5
22.5
33.5
44.5
5
0 0.5 1 1.5 2
Current, nA
Mea
sure
d vo
ltag
e, V
Channel 1.5 nA
Channel 15 nA
ASLAF response to the produced electric current
• linearity
• constant signal ratio
Workshop “Solar influences on the ionosphere and magnetosphere”, Sozopol, Bulgaria, 7-13 June 2009
ASLAF – some characteristics
Signal test measurements from both channels
0
1
2
3
4
5
0 5000 10000 15000 20000 25000 30000 35000
Measurement number
Cur
rent
, nA
Workshop “Solar influences on the ionosphere and magnetosphere”, Sozopol, Bulgaria, 7-13 June 2009
ASLAF – some characteristics
0
0.0005
0.001
0.0015
0.002
0.0025
0.003
0 1000 2000 3000 4000 5000 6000 7000
Measurement number
Noi
se, V
Channel 15 nA
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0 1000 2000 3000 4000 5000 6000 7000
Measurement numberN
oise
, V
Channel 1.5 nA
Noise measurements, internal power on
The noise in the Channel 15 nA is practically zero, and the one in Channel 1.5 nA is very low, with average value of 2.6 mV, what is near the sensitivity threshold.
Workshop “Solar influences on the ionosphere and magnetosphere”, Sozopol, Bulgaria, 7-13 June 2009
-80
-60
-40
-20
0
20
40
60
80
100
-100 -75 -50 -25 0 25 50 75 100
Angle, deg
Rel
ativ
e er
ror,
%Channel 15 nAChannel 1.5 nA
0
0.2
0.4
0.6
0.8
1
1.2
-100 -50 0 50 100
Emission angle, deg
Nor
mal
ized
sig
nal
Channel 15 nAChannel 1.5 nAFitting curve
ASLAF – some characteristics
Angular dependence of the measured signal
c
eey
bxabxa 22 )()(
Fitting curve:
Workshop “Solar influences on the ionosphere and magnetosphere”, Sozopol, Bulgaria, 7-13 June 2009
Data processing and analysis
• modeling the absorption process;
• obtaining the Lyman-alpha emission profile;
• computing the O2 density, pressure and T profiles;
• comparing the obtained profiles with all other available measurements;
• analysis of the results.
Consecutive steps:
Workshop “Solar influences on the ionosphere and magnetosphere”, Sozopol, Bulgaria, 7-13 June 2009
Data processing and analysis
Retrieval of the density, pressure and temperature profiles
The photoabsorption cross-section σ is defined fromlneII )(
0 )()( where I0 and I are the incident and transmitted intensities, n is the gas density, l is the path length and λ is the wavelength. For a mixture of gases we have
i
iiTT nn )()( i
iiT )()(
– σT, nT – total cross-section and number density;– ni, σi, δi – number density, cross-section and mixing ratio for the ith component.Assuming, that O2 is the basic absorber, we can write:
)(22fOOT
where f is a correction to include the absorption from other gases.Workshop “Solar influences on the ionosphere and magnetosphere”, Sozopol, Bulgaria,
7-13 June 2009
Data processing and analysis
dIIT )(
i
ii dhmngdpdh
dp
pH
11 mgkTH
For a thin atmospheric layer with thickness dh and angle of the incident L radiation θ the absorbed increment is:
The total intensity is defined as
Taking into account the pressure change across the layer, the expression for the pressure scale length H and its connection with the temperature
dhfOnIdI sec)()()()( 2
the equations for nO2, p, and T can be derived.
Workshop “Solar influences on the ionosphere and magnetosphere”, Sozopol, Bulgaria, 7-13 June 2009
Data processing and analysis
dh
hdR
hRhOn
E
)(
)(
1
)(
cos)( 2
1
)(cos
R E RR
dRKp
)(33
)( 22 OKn
p
OKn
p
k
mgT
Basic equations to compute the density, pressure and temperature profiles:
fdI
dIE
)(
)()(
)( 2On
mngK i
ii
TT IhIR )(
Where the effective cross-section σE, the level constant K and the ratio R are expressed by
Workshop “Solar influences on the ionosphere and magnetosphere”, Sozopol, Bulgaria, 7-13 June 2009
Atmospheric model and quantities, to be used in the calculations:
• Plane-parallel atmosphere;• Upper limit at 100 km;• parallel homogeneous layers;• Line-by-line calculations;• Measured intensity in and outside of the atmosphere and
shape of the Lyman-alpha line;• The rocket coordinates and the corresponding position of the
Sun towards it;• The photoabsorption cross-section;• The solar zenith angle θ.
Data processing and analysis
Workshop “Solar influences on the ionosphere and magnetosphere”, Sozopol, Bulgaria, 7-13 June 2009
Results and conclusions.
A modern Lyman-alpha detector (ASLAF) was designed and manufactured;
ASLAF passed successfully all tests performed before a rocket start;
The detector is an ionization chamber with work characteristics p=20 mb, U=60 V;
There are two measuring channels with ranges 1.5 nA and 15 nA, characterized with linearity, constant data ratio between them and low noise signal;
The channels monitoring the power supply to the ionization chamber and the temperature work well;
The power supply to the ionization chamber remain stable, 60V, with deviations from this value less then 1V;
The device is of very good quality and can be used in rocket experiments for measuring the Lα flux.
Lyman-alpha detector
Workshop “Solar influences on the ionosphere and magnetosphere”, Sozopol, Bulgaria, 7-13 June 2009
1) Preparation for taking part in future rocket experiments with ASLAF (detector of the direct solar Lyman-alpha radiation);
2) Development of a new device to register the scattered solar Lyman-alpha radiation in the atmosphere;
3) Developing Lyman-alpha detector for satellite measurements;
4) Use of other, more sensitive detectors of Lyman-alpha radiation;
5) Improvement of the signal amplification and the power supply.
Future alternatives:
Results and conclusions.
Workshop “Solar influences on the ionosphere and magnetosphere”, Sozopol, Bulgaria, 7-13 June 2009
Thanks for
your
attentio
n!