university of tokyo dept. aeronautics and astronautics 43rd aiaa aerospace sciences meeting, reno,...

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



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/




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]




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




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




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




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




ICP instability

Video images

RF power 750 W , Argon




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




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.




Tangential flow stabilization

Analogy with the planer geometry

Buoyancy force

Gravity

Stable

Unstable

Buoyancy force

Centrifugal force

Buoyancy forceStable

RA

mRV

bore

/~/~2

2




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




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.




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.




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




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




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.




Stable ICP generation w/o tangential flow



43rd AIAA Aerospace Sciences Meeting, Reno, NVStabilization using LASER PLASMA

Requirement for the stabilization

There should be some mechanismswhich keep the ICP geometry axisymmetric




Experimental setup

CO2 TEM00 LaserWage length 10.6 mMax. power 2 kW

SpecificationsSpecifications

Condensing lensMaterial ZnSeFocal length 210 mmF-number 6.3




Fundamental experiment

Laser 700 W + RF 0W Laser 700 W + RF 700W

LSP

Ignition rod

Focalpoint

Lens

Laser

Coil





LSP

Ignition rod

Focalpoint

CoilLens

Laser





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




Double tube configuration

LSP

Ignition rod

Focalpoint

Lens

Laser

Coil




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




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




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.




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




Other researches

Herdrich, G., et.al., @ IRS J.Thermophyscs Heat Trans., Vol16, 448, 2002

university of tokyo dept. aeronautics and astronautics 43rd aiaa aerospace sciences meeting, reno,...

Documents