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University of TokyoDept. Aeronauticsand Astronautics
43rd AIAA Aerospace Sciences Meeting, Reno, NV
Inductively Coupled Plasmas Supported by Laser Plasmas for High
Enthalpy Flow
University of TokyoUniversity of Tokyo
O O Takayoshi InoueTakayoshi Inoue
Susumu UeharaSusumu Uehara
Kimiya Kimiya KomurasakiKomurasaki
Yoshihiro Arakawa Yoshihiro Arakawa
University of TokyoDept. Aeronauticsand Astronautics
University of TokyoDept. Aeronauticsand Astronautics
43rd AIAA Aerospace Sciences Meeting, Reno, NVNext decade of the space exploration
Report produced by “SSEDS”
“New Frontiers in the Solar System : An Integrated Exploration Strategy ”
THE NATIONAL ACADEMIES PRESS,Washington DC, 2003.
“Venus In Situ Explorer” is one of the prioritized missions
http://www.nap.edu/
University of TokyoDept. Aeronauticsand Astronautics
University of TokyoDept. Aeronauticsand Astronautics
43rd AIAA Aerospace Sciences Meeting, Reno, NV
Venus probe
Pioneer Venus ( 1978 )
Sever environment around the probe
Heat flux ~ 104 W/cm2
Specific enthalpy ~ 44 MJ/kgStagnation pressure ~ 0.7 MPa
Thermal Protection System (TPS) is a single-point-failiure subsystem•TPS performance evaluation•Development of new TPS material
[B.Laub, and E.Venkatapathy; Proceedings of International Workshop on Planetary Probe Atmospheric Entry and Descent Trajectory Analysis and Science, Lisbon, 2003]
University of TokyoDept. Aeronauticsand Astronautics
University of TokyoDept. Aeronauticsand Astronautics
43rd AIAA Aerospace Sciences Meeting, Reno, NV
Need in Ground Facility
State of development of ICP wind tunnelsPower level operation
pressureNAL/ JAXA (Japan) 100-kW IPG 1 ~ 50
kPaIRS ( Stuttgart Univ.) 350-kW IPG3 ~ 2 kPavon Karman Inst. 1-MW IPG3 .5 ~ 10 kPa
100-kW IPG4 1 ~ 100 kPa
Inductively Coupled Plasma (ICP)wind tunnel
Atmospheric constituent of Venus
96 % CO2
(H2O, SO2….)
Mars (Current target) Venus (Next target)Higher pressure of 0.7 MPa
・ electrodeless・ less contamination
University of TokyoDept. Aeronauticsand Astronautics
University of TokyoDept. Aeronauticsand Astronautics
43rd AIAA Aerospace Sciences Meeting, Reno, NV
Objectives
1.1. To clarify the characteristics of To clarify the characteristics of Inductively Coupled Plasma with pressure of more than 1 atmInductively Coupled Plasma with pressure of more than 1 atm
» Development of an ICP generatorDevelopment of an ICP generator» Operational conditionOperational condition» StabilityStability
2.2. A proposal to stabilize the ICP by using a Laser plasmaA proposal to stabilize the ICP by using a Laser plasma
University of TokyoDept. Aeronauticsand Astronautics
University of TokyoDept. Aeronauticsand Astronautics
43rd AIAA Aerospace Sciences Meeting, Reno, NV
ICP generator
Tangential flow injection Tangential flow injection ringring
RF power supply1.2 kW
[13.56 MHz]
Impedance MatchingNetwork
ICP discharge chamberICP discharge chamber
Load coil5 turns – 30 mm in diam.
Work gasArgon
University of TokyoDept. Aeronauticsand Astronautics
University of TokyoDept. Aeronauticsand Astronautics
43rd AIAA Aerospace Sciences Meeting, Reno, NV
Atmospheric ICP generation
I Set the mass flow rate to 0 g/s and the RF power output to 500 W resulting capacitively coupled plasma generation.
II Gradually increased the mass flow rate and pressure coming to about 1 atm the mode transition occurred .
III Once the ICP were produced, the flow rate, the pressure and RF power could be adjusted without inductive-capacitive mode transition.
I II III
University of TokyoDept. Aeronauticsand Astronautics
University of TokyoDept. Aeronauticsand Astronautics
43rd AIAA Aerospace Sciences Meeting, Reno, NV
ICP instability
Video images
RF power 750 W , Argon
University of TokyoDept. Aeronauticsand Astronautics
University of TokyoDept. Aeronauticsand Astronautics
43rd AIAA Aerospace Sciences Meeting, Reno, NV
Operational condition
Tangential flow effect
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0 0.05 0.1 0.15 0.2
Axial mass flow rate, g/s
Tan
gent
ial m
ass
flow
rat
e, g
/s
Unstable
Tangential flow injection bores 2 bores
1 mm in diam./2 to the axis
Min. mass flow rateMin. mass flow rate
Pressure regulationgas : 0 g/s
No contribution of Axial flow to the stable ICP generation
University of TokyoDept. Aeronauticsand Astronautics
University of TokyoDept. Aeronauticsand Astronautics
43rd AIAA Aerospace Sciences Meeting, Reno, NV
Operational condition
Minimum mass flow rate
•Independent of the RF power•Increase with the pressure
Maximum mass flow rate•Dependent on the RF power•Decrease with the pressure
Instabilitiesin a high power operationin a low mass flow rate operation
have been reported.
Instabilitiesin a high power operationin a low mass flow rate operation
have been reported.
University of TokyoDept. Aeronauticsand Astronautics
University of TokyoDept. Aeronauticsand Astronautics
43rd AIAA Aerospace Sciences Meeting, Reno, NV
Tangential flow stabilization
Analogy with the planer geometry
Buoyancy force
Gravity
Stable
Unstable
Buoyancy force
Centrifugal force
Buoyancy forceStable
RA
mRV
bore
/~/~2
2
University of TokyoDept. Aeronauticsand Astronautics
University of TokyoDept. Aeronauticsand Astronautics
43rd AIAA Aerospace Sciences Meeting, Reno, NV
Injection rings
Diameter of the bores
Axial gas
Tangential flow
Coil
0 10 20 30 40 50 mm
TypeI (ƒ Ó2 mm) I I ( ƒ Ó1 mm) I I I ( ƒ Ó0. 7 mm)
2- ƒ Ó
I nj ect i on head
Type I 2 mmType II 1 mmType III 0.7 mm
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0 0.1 0.2 0.3 0.4 0.5
Pressure, MPa
Ma
ss fl
ow
ra
te, g
/s
2 mm
1 mm
0.7 mm
University of TokyoDept. Aeronauticsand Astronautics
University of TokyoDept. Aeronauticsand Astronautics
43rd AIAA Aerospace Sciences Meeting, Reno, NV
Effect of the coil location
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0 0.2 0.4 0.6
Pressure, MPa
Ma
ss flo
w r
ate
, g
/s
70mm
50 mm
40 mm
30 mm
20 mm
10 mm
Min. mass flow rateMin. mass flow rate
I nj ect i on head
10 ~ 70 mm
Tangential flow injection bores 2 bores
1 mm in diam./2 to the axis
The decay of tangential flow lead tothe increase in the mass flow rate.
University of TokyoDept. Aeronauticsand Astronautics
University of TokyoDept. Aeronauticsand Astronautics
43rd AIAA Aerospace Sciences Meeting, Reno, NV
Injection rings
Injection angle
Axial gas
Tangential flow
Coil
0 10 20 30 40 50 mm
TypeI V(φ 1 mm)
2-φ
I nj ecti on head
Type IV has the angle of /4
to the axis
0
0.05
0.1
0.15
0.2
0.25
0.3
0 0.1 0.2 0.3 0.4 0.5
Pressure, MPa
Ma
ss fl
ow
ra
te, g
/s
90 deg.
45 deg.
University of TokyoDept. Aeronauticsand Astronautics
University of TokyoDept. Aeronauticsand Astronautics
43rd AIAA Aerospace Sciences Meeting, Reno, NV
Oscillation
0 0.2 0.4 0.6 0.8 1Time, s
Inte
nsi
ty,
a.u
.
0 20 40 60 80 100Frequency, Hz
Po
we
r sp
ect
ra,
a.u
. 15 Hz 17 Hz
34 Hz51 Hz
68 Hz
32 Hz
CCD imagesCCD images
Light emissionReflected power
University of TokyoDept. Aeronauticsand Astronautics
University of TokyoDept. Aeronauticsand Astronautics
43rd AIAA Aerospace Sciences Meeting, Reno, NV
Oscillation frequency
Frequency v.s. Mass flow rate
0
5
10
15
20
25
30
0 0.2 0.4
Mass flow rate, g/s
Osc
illa
tion
fre
qu
en
cy, H
z .
Type I
Type II
Type III
Type IV
0
5
10
15
20
25
0 0.2 0.4
Mass flow rate, g/s
Osc
illa
tion
fre
qu
en
cy, H
z .
70mm
50 mm
40 mm
30 mm
20 mm
10 mm
Strong relation between the frequency and the mass flow rate
University of TokyoDept. Aeronauticsand Astronautics
University of TokyoDept. Aeronauticsand Astronautics
43rd AIAA Aerospace Sciences Meeting, Reno, NV
Interim summary
Experimental investigation on Inductively Coupled Plasmas stability were conducted , and can be summarized as follows;
ICP was stably generated with 0.1 ~ 0.4 MPa atmospheres by using 1.25 kW RF power source.
Stably operational condition became limited with the increase in the pressure.
Tangential flow injection has the essential role in the stable ICP generation though the design of the injection ring affects the operational conditions of ICPs.
University of TokyoDept. Aeronauticsand Astronautics
University of TokyoDept. Aeronauticsand Astronautics
43rd AIAA Aerospace Sciences Meeting, Reno, NV
Stable ICP generation w/o tangential flow
University of TokyoDept. Aeronauticsand Astronautics
University of TokyoDept. Aeronauticsand Astronautics
43rd AIAA Aerospace Sciences Meeting, Reno, NVStabilization using LASER PLASMA
Requirement for the stabilization
There should be some mechanismswhich keep the ICP geometry axisymmetric
University of TokyoDept. Aeronauticsand Astronautics
University of TokyoDept. Aeronauticsand Astronautics
43rd AIAA Aerospace Sciences Meeting, Reno, NV
Experimental setup
CO2 TEM00 LaserWage length 10.6 mMax. power 2 kW
SpecificationsSpecifications
Condensing lensMaterial ZnSeFocal length 210 mmF-number 6.3
University of TokyoDept. Aeronauticsand Astronautics
University of TokyoDept. Aeronauticsand Astronautics
43rd AIAA Aerospace Sciences Meeting, Reno, NV
Fundamental experiment
Laser 700 W + RF 0W Laser 700 W + RF 700W
LSP
Ignition rod
Focalpoint
Lens
Laser
Coil
University of TokyoDept. Aeronauticsand Astronautics
University of TokyoDept. Aeronauticsand Astronautics
43rd AIAA Aerospace Sciences Meeting, Reno, NV
Fundamental experiment
LSP
Ignition rod
Focalpoint
CoilLens
Laser
University of TokyoDept. Aeronauticsand Astronautics
University of TokyoDept. Aeronauticsand Astronautics
43rd AIAA Aerospace Sciences Meeting, Reno, NV
Fundamental experiment
Laser 700 W + RF 0W Laser 700 W + RF 700W
Stabilization w/o tangential flow was successfully demonstrated
Zoom of the discharge torch
CCD images
Absorbed laser power 300 W
LSP
Ignition rod
Focalpoint
CoilLens
Laser LaserGas
University of TokyoDept. Aeronauticsand Astronautics
University of TokyoDept. Aeronauticsand Astronautics
43rd AIAA Aerospace Sciences Meeting, Reno, NV
Double tube configuration
LSP
Ignition rod
Focalpoint
Lens
Laser
Coil
University of TokyoDept. Aeronauticsand Astronautics
University of TokyoDept. Aeronauticsand Astronautics
43rd AIAA Aerospace Sciences Meeting, Reno, NV
LSP in the double tube configuration
• LSP was sustained in the inner tube stably
• Operational condition was improved
LSP generation limitLSP generation limit
LSP
Ignition rod
Focalpoint
Lens
Laser
Coil
0
0.1
0.2
0.3
0.4
20304050
Travel distance of condense lens, mm
Min
. m
ass
flow
rat
e, g
/s
0.1
0.12
0.14
0.16
0.18
0.2
Max
. pr
essu
re,
MP
a
University of TokyoDept. Aeronauticsand Astronautics
University of TokyoDept. Aeronauticsand Astronautics
43rd AIAA Aerospace Sciences Meeting, Reno, NV
ICP generation in the double tube configuration
Z~45mm
Z~30mmZ ~ 40 mm
Also in the double tube configuration,ICP was generated stably w/o tangential flow injection
LSP ICP
LaserGas
Innertube
Coil Outer tube
University of TokyoDept. Aeronauticsand Astronautics
University of TokyoDept. Aeronauticsand Astronautics
43rd AIAA Aerospace Sciences Meeting, Reno, NV
Summary
Tangential flow injection has the essential role in the stable atmospheric ICP generation though the design of the injection ring affects the operational conditions of ICPs.
By using Laser plasma, atmospheric ICP can be generated stably.
Double tube configuration enable to control the flow parameters of the LSP and ICP independently.
University of TokyoDept. Aeronauticsand Astronautics
University of TokyoDept. Aeronauticsand Astronautics
43rd AIAA Aerospace Sciences Meeting, Reno, NV
Next issues
In this study….
Modeling of the stabilization is not enough No production of the free jet. No discussion in terms of the enthalpy and the
efficiency.
Efforts should be directed to…
Establishment of an analytical model of the stability. Acceleration of the flow by a Laval nozzle. Evaluation of the performance of the Atmospheric
ICPG and its relation with the stability
University of TokyoDept. Aeronauticsand Astronautics
University of TokyoDept. Aeronauticsand Astronautics
43rd AIAA Aerospace Sciences Meeting, Reno, NV
Other researches
Herdrich, G., et.al., @ IRS J.Thermophyscs Heat Trans., Vol16, 448, 2002