Performance of Two-Dimensional Applied-Filed Magneto-Plasma-Dynamic Thruster

Transcription

1 Perfrmance f Tw-Dimensinal Applied-Filed Magne-Plasma-Dynamic Thruser IEP Presened a he 31 s Inernainal Elecric Prpulsin nference, Universiy f Michigan, Ann Arbr, Michigan, USA Akira IWAKAWA Insiue f Space and Asrnauical Science, 3-1-1, Yshindai, Sagamihara-shi, Kanagawa , Japan Daisuke Nakaa Insiue f Space and Asrnauical Science, 3-1-1, Yshindai, Sagamihara-shi, Kanagawa , Japan and Hishi Kuninaka Insiue f Space and Asrnauical Science, 3-1-1, Yshindai, Sagamihara-shi, Kanagawa , Japan Absrac: A w-dimensinal applied-field Magne-Plasma-Dynamic hruser (2D AF- MPDT) has been develped. A srng applied magneic field mre han 1 T can be applied he 2D AF-MPDT. Successful perain wih applied magneic field srengh frm T 1 T was achieved. A hrus measuremen using hrus-sand measure he crrec hrus was n pssible because f he srng magneic ineracin beween he cil and he vacuum vessel. The degree and srengh f his ineracin is differen fr every perain. T avid he magneic ineracin, a arge hrus measuremen was adaped. In his paper, he hrus measured by his mehd is repred and he hrus efficiency was evaluaed. Nmenclaure B V d V cil J d J cil T E discharge P P cil P discharge η = discharge ime = applied magneic field = discharge vlage (per channnel) = vlage drp f cil = discharge curren (3ch average) = cil curren = hrus = cnsumed energy f discharge = al inpu pwer = inpu energy f cil = inpu energy f discharge = hrus efficiency Graduae Suden, Deparmen f Aernauics and Asrnauics, iwakawa@ep.isas.jaxa.jp Researcher, Japan Space Explrain ener, nakaa@ep.isas.jaxa.jp Prfessr, Space Transprain Divisin, kuninaka@isas.jaxa.jp 1

2 W H D subscrip d h = widh = heigh = deph = discharge chamber = hruser head = arge I. Inrducin In he near fuure, bh higher hrus and higher specific impulse are necessary fr large scale, inerplaneary r rbial ransfer missins. High-pwer elecric prpulsin devices can achieve hese missins. A Magne- Plasma-Dynamic hruser (MPDT), which is a well knwn elecric prpulsin device 1 is a very prmising candidae fr high-pwer elecric prpulsin. 2, 3 The advanage f MPDTs is heir very high hrus-weigh rai cmpared wih her elecric prpulsin devices. In addiin, he hrus efficiency f MPDTs is imprved wih increasing inpu pwer. MPDTs are able be idenified by he shape f he elecrde and he exisence f he exernal magneic field. Typical self-field MPDTs ha have been sudied by sme researchers 4, 5 need several hundreds f kw fr accepable efficiency. Hwever, in he near fuure, i is difficul bain hundreds f kw n a space craf. On he her hand, applied-field MPDTs (AF-MPDTs) are able achieve accepable efficiency wih ens f kw. Hence, i is a beer candidae fr pracical use in he near fuure. axial AF-MPDTs have been sudied by sme researchers. 6 1 Hwever, i is difficul pimize he disribuin f he magneic field because he hrus prducin mechanism f caxial AF-MPDTs is very cmplex due he j B Lrenz frce which is n parallel he hrus frce. In he case f w-dimensinal AF-MPDTs (2D AF-MPDTs), which is a s-called rssed-field Accelerar 11 15, i is easy analyze he pimal magneic field because he direcin f j B is parallel he hrus axis. In 196s, a rssed-field Accelerar was sudied by sme researchers There is a sudy ha applied magneic field ver 1 T. These experimens were peraed by large mass flw rae. An experimen seup was cnsruced evaluae he hrus perfrmance f he 2D AF-MPDT. This seup is able apply a srng magneic field and perae wih small mass flw rae. In a previus sudy, he hrus was measured by he parallel-pendulum mehd 5, 16. Hwever, i is n pssible measure he crrec hrus because f he magneic ineracin beween he cils and he chamber walls. In AF-MPDT, aviding he magneic ineracin a arge mehd was adped. In his paper, measuring he hrus by his arge mehd and evaluaing he hrus perfrmance f he 2D AF-MPDT is he main sabjecive. 2

3 Pwer Supply Pulse Frming Newrk Rgwski il All urren il urren Discharge urren Air-red Tridal il e g r a h c is D T il T Phcupler LED Displacemen Sensr Discharge Vlage Mass Flw Rae Digial Pressure Gauge Reservir Tank Thruser Head Targe m.8 ϕ Thrus Oupu 2. m T Vacuum Pump Figure 1. Schemaic f he experimenal seup. II. Experimenal Seups The schemaic f he experimenal seup is shwn in Fig.1. A. Thruser Head A schemaic f he 2D AF-MPDT seup is shwn in Fig.2. The 2D AF-MPDT has 3 pairs f elecrdes keep unifrmiy f he crss direcin and ease f prcessing, he ande is made f cpper and he cahde is made f ungsen. The insular is made f brn niride r resin. The size f he hruser head is 94 mm (W h ) 12 mm (H h ) 12 mm (D h ). The size f he discharge chamber ha means he space beween he ande and cahde, is 4 mm (W d ) 1 mm (H d ) 5 mm (D d ). H h H d D d D h Figure 2. Appearance f he 2D AF-MPDT. Lef figure is a phgraph f he 2D AF-MPDT, righ figure is a schemaic picure. 3

4 (a) N cnneced (b) 1 resisr cnneced PF A K PF A K i l i l (c) 2 resisrs cnneced (d) 3 resisrs cnneced PF A K PF A K i l i l Figure 3. Elecric circui diagram f he experimenal seup. A is ande, K is cahde. Blue lines indicae a shr-circuied, red lines indicae cnnecin he cil. B. Applied Magneic Field The 2D AF-MPDT has a quasi-helmhlz cil apply an exernal magneic field. The cils cnsis f 9 urns f 4-mm-diameer cpper wires. The inner diameer f he cils is 8 mm. The disance beween hese w cils is 48 mm esablishing a quasi-helmhlz cil seup. These cils are able frm a relaively-unifrm magneic field in he discharge chamber f 1 T wih a cil curren f 6.3 ka. The applied magneic field is linear he cil curren. The inducance f his quasi-helmhlz cil is 21 mh.. Pwer Supply Sysem The discharge curren and he cil curren are supplied by a 5-ladder.2 mf L- pulse frming newrk (PFN). The energy srage capabiliy f he PFN is 2 kj and can prduce recangular curren pulses.5 ms and curren levels up 22 ka. The curren supplied frm he PFN is divided in he discharge curren and he cil curren hrugh he parallel resisance divider. The diagram f he divider curren is shwn in Fig.3. There are 6 resisr, 3 resisrs are cnneced he elecrde, respecively. Oher 3 resisrs are able cnnec he cil. If ne resisr is cnneced he cil, her 2 resisrs are shr-circuied, see in Fig.3. In his way, i was achieved ha he cil curren is n linear he discharge curren and he impedance f he 2D AF-MPDT is kep alms cnsan. D. Vacuum Sysem The 2D AF-MPDT is peraed in a seel vacuum vessel.8 m in diameer and 2. m in lengh. The inner surface f he vacuum vessel is cmpleely cvered wih Mylar shees in rder avid elecric ineracin beween plasma flw and vacuum vessel. A vacuum pressure f 1 3 Pa is mainained by an il diffusin pump wih a pumping capabiliy f 3,7 l/s, which is bsed by a mechanical bser pump and an il rary pump wih a pumping capabiliy f 25, l/s, and 7,5 l/s, respecively. The pressure f he vacuum vessel is measured by an inizain vacuum gauge a pressures belw 1 1 Pa. Abve his pressure, a Pirani gauge is used. E. Prpellan Feed Prpellan is injeced hrugh a fas acing valve (FAV). The FAV prvides prpellan gas he 2D AF- MPDT frm he reservir ank wih a shr durain f 5 ms. The mass flw rae was bained by he measured decrease f he reservir pressure. In his paper, all experimens were perfrmed under a fixed mass flw rae f.2 g/s wih argn gas as a prpellan. 4

5 2 V A, e, 16 g n a e r l u 12 V e e g r g r 8 a a h c h c is D is D Time, ms A A k, k, n e n r e r u u l a il T Discharge urren (h2), A Tal urren, ka Discharge Vlage, V il urren, ka Figure 4. The sample wavefrm f he discharge. F. Vlage and urren Measuremen In MPDT s perain, he measuremen sysem f he discharge characerisics has n effec n he discharge f he 2D AF-MPDT. A phcupler is used fr he measuremen f he discharge vlage and a Rgwski cil and an air-cred ridal cil are used fr he measuremen f he curren. The cnsumed energy is calculaed frm he fllwing expressin Eq.1 by he discharge vlage and curren. E discharge = J d () V d ()d (1) A sample wavefrm is shwn in Fig.4. In his figure, red lines are using lef axis and blue lines are using righ axis. The red slid line indicaes he discharge vlage, he red dashed lines indicae he discharge curren f cener channel. The blue slid line indicaes he al curren supplied frm PFN, he blue dashed line indicaes he cil curren. The applied magneic field f.16 T crrespnds a cil curren f 1. ka. The inerval f inegrain is frm.1 ms.6 ms, he blue area shwn in Fig.4. G. Thrus Measumen The parellel-pendulum mehd, ha cnsiss f he pendulum hrus sand and he laser displacemen sensr, was used fr hrus measuremen f he caxial MPDT in ISAS fr a lng ime. The hruser head is placed n he hrus sand, and he ampliude f he scillaing sand is deeced by a laser displacemen sensr. Hwever, i was n reliable measure he hrus f he 2D AF-MPDT crrecly when here is exernal magneic field, because f he magneic ineracin beween he cils and he vacuum vessel. The degree and he srengh f he magneic ineracin were differen fr every perain. Fr his reasn, a arge measuremen sysem, arge-mehd was adped. The arge is made f paper and Mylar shee. The schemaic f he arge is shwn in Fig.5. The frm f he arge is apered, called cnical arge, 17 avid ver esimain. The size f he arge is 8 mm (W ) 1 mm (H ) 8 mm (D ). This size is bigger han he crss-secinal area f he discharge chamber f he 2D AF-MPDT. And he arge is suspended frm he vacuum vessel ceiling by w flurcarbn wires. The cnfigurain f he arge measuremen sysem is shwn in Fig.6. The appearance f he hruser head and arge is shwn in Fig.7. The disance beween he hruser head and arge is 1.5 cm. The ampliude f he scillaing arge is deeced by an LED displacemen sensr. The minimum resluin f he LED displacemen sensr is less han 5 µ m. 5

6 H W Figure 5. Schemaic f he 2D cnical arge. LED displacemen Sensr Targe Figure 6. Schemaic f he arge measuremen sysem. 1.5 cm Figure 7. Appearance f he hruser head and he arge. 6

7 LED displacemen sensr il Seel ball Targe Figure 8. Schemaic f he arge calibrain. H. alibrain The cnical arge is calibraed by w differen weigh seel balls. The schemaic f he calibrain is shwn in Fig.8. A he iniial sae, he seel ball was fixed a cerain heigh by he magneic frce f he cil. Then, he cil curren was urned ff, leing he ball cllide wih he arge. The surface f he arge was sprayed grease cllisin, he seel ball sicks he arge. The cndiin f calibrain is summarized in Table 1. The resuls f he calibrain are shwn in Fig.9. Frm his figure, he relainship beween he impulse and he scillain is linear. The cefficien is Ns/V. In he fllwing, he resul f he hrus is calculae wih his cefficien. Table 1. ndiin f he arge calibrain. Weigh f irn ball, g Heigh f iniial irn ball, cm impulse, Ns

8 .7.6 s.5, e.4 ls u p.3 I m Ampliude, V Figure 9. Resul f he arge calibrain. III. Experimenal Resuls and Discussin The resuls f he experimen is summarized in Table 2. The appearance f he discharge f a cerain cndiin is shwn in Fig.1. Table 2. Resul f his series experimen. he number f he resisr B, T V d,v J d, A T, N P, kw T/P, mn/kw η, %

9 Figure 1. Discharge appearance f he 2D AF-MPDT. Lef figure is frn view, righ ne is side view. A. Thrus The relainship beween he applied magneic field and he hrus is shwn in Fig.11. In his figure, he mass flw rae was fixed.2 g/s. Thrus increases wih applied magneic field. Under hese cndiins, he hrus is n sauraed. There is a pssibiliy ha he hrus increases wih srnger applied magneic field han 1 T. 5 Thrus, N line cil 1 line cil 2 lines cil 3 lines cil Applied Field, T Figure 11. Relainship beween applied magneic field and hrus. Mass flw rae was fixed.2 g/s wih argn gas as a prpellan. B. Thrus Efficiency The hrus efficiency is calculaed by fllwing expressin. Inpu pwer is calculaed by fllwing expressin. η = T 2 2ṁP (2) P = P discharge + P cil (3) 9

10 Thrus Efficiency, % line cil 1 line cil 2 lines cil 3 lines cil Applied Field, T Figure 12. Relainship beween applied magneic field and hrus efficiency. Operain cndiin; prpellan gas is argn, mass flw rae is.2 g/s. nsumed energy f he discharge and he cil is calculaed by fllwing expressins. P discharge = E discharge (4) P cil = V cil J cil (5) In Eq.5, he vlage drp f he cil was esimaed by he impedance f he cil and he frequency f he curren. The resul f he relainship beween applied magneic field and hrus efficiency is shwn in Fig.12. In his figure, he hrus efficiency decreases mnnically wih an increasing magneic field.. Discussin The experimen in his paper, was peraed by ne PFN. The discharge vlage, he discharge curren and he cil curren are uniquely fixed by charge vlage f he PFN. I is n suiable esimae he hrus perfrmance f he 2D AF- MPDT because i is impssible increase applied magneic field fr a cnsan discharge curren. In fig.11, here is a pssibiliy ha he hrus was veresimaed wih small magneic field. Hence, he hrus efficiency is esimaed mre han 3 %. There is a pssibiliy ha he hrus was veresimaed because f he pressure beween he arge and hruser increased. Fr his reasn, he esimaed hrus is up wice as large as crrec hrus. I was n achieved measure he crrec hrus hwever i was achieved avid he magneic ineracin by arge measuremen sysem. I is necessary measure he crrec hrus by aviding he magneic ineracin r by aviding he pressure increasing in he arge mehd. IV. nclusin A w-dimensinal applied-field Magne-Plasma-Dynamic hruser (2D AF-MPDT) has been develped. The hrus measuremen sysem using a plume arge and an LED displacemen sensr was cnsruced. In his paper, i was repred under differen cndiins. Using argn gas as prpellan, he mass flw rae was fixed.2 g/s, he applied magneic field ranges frm T 1 T. As a resul f his series f experimens, he hrus was increased wih increasing applied magneic field and he hrus efficiency was decreased mnnically wih increasing applied magneic field. Ande ersin was n bserved. Hwever, here was n evidence ha he crrec hrus was measured because f he hrus was excepinally large. In fuure wrk, we have measure he crrec hrus in ne way r anher. 1

11 References 1 R. G. Jahn, Physics f Elecric Prpulsin. McGraw-Hill, New Yrk, M. Marinez-Sanchez, Spacecraf Elecric Prpulsin - An Overview, Jurnal f Prpulsin and Pwer, Vl. 14, N. 5, pp , K. Sankaran, L. assady, A. D. Kdys, and E. Y. hueiri, A Survey f Prpulsin Opins fr arg and Piled Missins Mars, The annals f he New Yrk Academy f Science, Vl. 117, pp , May E. Y. hueiri and J. K. Ziemer, Quasi-Seady Magneplasmadynamic Thruser Perfrmance Daabase, Jurnal f Prpulsin and Pwer, Vl. 17, N. 5, pp , D. Nakaa, K. Tki, I. Funaki, Y. Shimizu, H. Kuninaka, and Y. Arakawa, Recen Sudy fr Elecrde nfigurain and Maerial Imprvemen in an MPD Thruser,, 43rd AIAA/ASME/SAE/ASEE Jin Prpulsin nference & Exhibi, cincinnai, OH, AIAA Paper, AIAA A. Sash and Y. Arakawa, Elecrmagneic Effecs in an Applied-Field Magnplasmadynamic Thruser, Jurnal f Prpulsin and Pwer, Vl. 8, N. 1, pp , T. Hirkazu, K. Yichi, and Y. Taka, Effecs f Applied Magneic Fields n Perfrmance f a Quasiseady Magneplasmadynamic Arc, Jurnal f Prpulsin and Pwer, Vl. 11, N. 2, pp , A. Kdys and E. Y. hueiri, A riical Review f he Sae-f-he-Ar in he Perfrmance f Applied-field Magneplasmadynamic Thrusers, 41s AIAA/ASME/SAE/ASEE Jin Prpulsin nference & Exhibi, ucsn, Arizna, AIAA paper, AIAA D. Haag and M. Ferig, Numerical Simulains f Magneplasmadynamic Thrusers wih axial Applied Magneic Field, 3h Inernainal Elecric Prpulsin nference, flrence, Ialy, IEP paper, IEP K. Kuba, I. Funaki, and Y. Okun, Flwfield Analysis in an MPD Thruser wih Applied Magneic Field, 44h AIAA/ASME/SAE/ASEE Jin Prpulsin nference & Exhibi, harfrd, T, AIAA paper, AIAA A. SHERMAN, Thereical Perfrmace f a rssed Field MHD Accelerar, ARS: JOURNAL, Vl. 32, N. 3, pp , V. H. Blackman and R. J. Sunderlamd, Experimenal Perfrmance f a rssed-field Accelerar, AIAA Jurnal, Vl. 1, N. 9, pp , M. R. Denisn and R. W. Ziemer, Invesigain f he Phenmena in rssed-field Accelerars, Fifh Biennial Gas Dynamics Sympsium, evansn, Illinis, AIAA Paper D. P. DULOS, Y.. L. WU, M. R. DENISON, and R. W. ZIEMER, Physical Prpery Disribuuins in a Lw-Pressure rssed-field Plsama Accelerar, AIAA Jurnal, Vl. 3, N. 11, pp , J. JEDLIKA and J. HAAKER, Sme Experimenal Observains n irculaing urren in a rssed Field Plasma Accelerar, AIAA Jurnal, Vl. 1, N. 5, pp , D. Nakaa, K. Tki, I. Funaki, Y. Shimizu, H. Kuninaka, and Y. Arakawa, Experimenal Sudy fr he Opimal Elecrde Gemery in an MPD Thruser, 45h AIAA Aerspace Sciences Meeing and Exhibi, ren, Nevada R. Yanagi and I. Kimura, New Type f Targe fr he Measuremen f Impulse Bis f Pulsed Plasma Thrusers, Jurnal f Spacecraf and Rckes, Vl. 19, N. 3, pp ,