Presentation on theme: "A Review of Laser Ablation Propulsion"— Presentation transcript:
1 A Review of Laser Ablation Propulsion Claude Phipps1, Willy Bohn2, Thomas Lippert3, Akihiro Sasoh4, Wolfgang Schall5 and John Sinko61Photonic Associates LLC, 200A Ojo de la Vaca Road, Santa Fe, New Mexico USA 87508Phone/Fax: ,2Bohn Laser Consult, Weinberg Weg 43, Stuttgart, Germany3Paul Scherrer Institut, CH5232 Villigen PSI, Switzerland4Department of Aerospace Engineering, Nagoya University, Chikusa-ku, Nagoya, Japan5DLR Institute of Technical Physics, Stuttgart, Germany (retired)6Micro-Nano GCOE, Graduate School of Engineering, Nagoya University, Chikusa-ku, Nagoya, JapanAdvanced Laser Technologies 2009Antalya, TurkeySeptember 30, 2009
2 Contents Benefits of laser ablation propulsion (LAP) Scope of this reviewHistory starting with pure photon propulsionPulsed laser ablation propulsionOperating rangeVapor and plasma regime theoryApplicationsLaser plasma thruster (LPT)Laser-driven in-tube accelerator (LITA)Liquid-fueled laser-plasma engineLightcraftLaser space debris mitigation (ORION)Direct launch to low earth orbitPromise for the future
3 Benefits of LAP1) Lower costs with laser launching. Today’s cost of launching one kg into low Earth orbit (LEO) is equivalent to the cost of gold.Greater than the price of gold!But it need not be so! [Myrabo Lightcraft flight, White Sands]Today’s LEO launch costsLaunch SystemMinimum Cost (k$/kg)Rockot10Shuttle12Athena 2Taurus20ISS, commercial22Pegasus XL24Long March CZ-2C30Athena41Photo: Courtesy Leik Myrabo
4 Benefits of LAP 2) Lower Dead Mass Do not have to fly turbines, pumps, tanks, exhaust nozzles, etc., along with the payload3) Variable Exhaust Velocity (crucial!)From chemical rockets up to and surpassing that of ion enginesAccomplished by varying intensity on target (t, As)Permits maximum efficiency flights1,2 in which exhaust and flight velocity are matched, leaving exhaust particles with zero momentum1C. W. Larson, F. B. Mead, Jr. And S. D. Knecht, “Benefit of constant momentum propulsion for large v Missions – applications in laser propulsion,” paper AIAA , 42d Aerospace Sciences Meeting, Reno, 5-8 January 20042Uchida, 1st International Symposium on Beamed Energy Propulsion, Huntsville, AL, 5-7 November 2002, AIP Conference Proceedings (2002)
5 Benefits of LAP 4) High thrust density 5) High thrust to mass ratio 30kN/m2 demonstrated in the PALLC minithruster35) High thrust to mass ratio15kN/kg demonstrated in Russian ASLPE engine46) High thrust efficiency125% expected for kW laser thruster5This is possible due to exothermic fuelsNot a trivial distinction for spacecraft3 C. R. Phipps, J. R. Luke, W. Helgeson and R. Johnson, AIP Conference Proceedings 830, (2006)4 Yu. Rezunkov, A. Safronov, A. Ageichik, M. Egorov, V. Stepanov, V. Rachuk, V. Guterman, A. Ivanov, S. Rebrov and A. Golikov, AIP Conference Proceedings 830, 3-13 (2006)5 C. R. Phipps, J. R. Luke and W. Helgeson, AIP Conference Proceedings 997, (2008)
6 Scope Propulsion by laser ablation Primarily, applications Less emphasis on:Pure photon propulsion, except for historical contextInertial confinement fusion except as a reference pointFundamental plasma physics theoryCoulomb explosions, LASNEX modeling, etcPhoto courtesy Yuri Rezunkov (time exposure of flight in lab)
7 History in a Nutshell Tsander Rezunkov ASLPE Fridrich Tsander, 1924: : Pure photon propulsionBut Cm = thrust / laser watt = 2/c = 6.7 mN/MWWolfgang Möckel 1972: Basic theory of laser driven rocketsArthur Kantrowitz6 1972: Laser ablation propulsion (LAP)Cm ≈ 100N/MW to 10kN/MW due to plume accelerationLeik Myrabo 20017: Flight to 72m altitude in New Mexico desertRezunkov 20064: 2N thrust demonstratedTsander6 A. Kantrowitz, Astronautics and Aeronautics 10 (5), (1972)7 L. N. Myrabo, paper AIAA , 37th AIAA/ASME/ SAE/ASEE Joint Propulsion Conference, 8-11 July 2001, Salt Lake City, UT (2001)Rezunkov ASLPE
8 Pulsed LAP Terminology Here are the most important parameters:1) Momentum coupling coefficient Cm=I / W=mvE/W = F/P2) Specific ablation energy Q* = W/m3) Exhaust velocity vE = CmQ*4) Specific impulse Isp = I /(mgo) = vE/go5) Mass usage rate6) Ablation efficiency hAB = WE/W = myvE2/(2W) = yCmvE/27) Energy conservationCmvE = CmIsp*go = (2/y)hABwhere y = <vx2>/(<vx>2) ≥ 1 is a parameter8 that is often ≈ 1(The CmvE product = 2.0 when hAB = y = 1, but can’t be larger unless hAB >1)[8Phipps & Michaelis, Laser and Particle Beams, 12(1), (1994)]
9 Operating Range From water cannons nearly to photon propulsion! [References below can be found in the JPP review paper]From water cannons nearly to photon propulsion!
10 Terminology, cont’d i = 2ne/(no + ne + ni) Some ancillary relationships among LSP parameters:8) Thrust efficiency hT = heohAB9) Fuel lifetime tAB = go2MIsp2/(2PhAB)[Severe penalty paid for Isp = 10s as in water cannons]Lots of thrust, but 10,000 times less tAB than if Isp =1000s10) Optimum coupling fluence Fopt = 480 t0.5 MJ/m211) Ionization fraction where (Saha equation):Opt. Coupling Fluence vs. ti = 2ne/(no + ne + ni)
11 Theory 12) Plasma regime model9: 13) Vapor regime model10: [In Eq. 12, A is mean atomic mass, Z is mean ionic charge state, Y = A/2[Z2(Z+1)]1/3.In Eq. 13, x = F/Fo, Fo = thrust fluence threshold,T = transmissivity from laser to surface, a = ablation layer absorption coefficient, r = target solid density and F = incident fluence] Plasma model was not meant to be valid as Z 0, Y , Vapor model was not meant to treat the plasma state. Problem: how do we make the transition between the two models?9 Isp is just a matter of intensity! See: Phipps et al. J. Appl. Phys., 64, 1083 (1988)10 New results: J. Sinko and C. Phipps, Appl. Phys. Lett., accepted for publication (2009)
12 Solution to the problem We use Cm = [i pp +(1-i) pv]/I = i Cmp + (1-i) Cmv VaporPlasma
13 Laser Plasma Thruster (Note: macro-LPT will not need T-mode) ms thruster (10mN, 250s)ns thruster (50mN, 3660s)See Phipps & Luke, reference 3.
14 LITA Laser in-tube Accelerator concepts of Sasoh11 11 A. Sasoh, S. Suzuki and A. Matsuda, Journal of Propulsion and Power, accepted for publication (2009).
15 Liquid-fueled Laser Engine 3-kW, 6.5-N engine design driven by 18x100-W fiber lasers5See Phipps, Luke and Helgeson, reference 5.
16 LightcraftMyrabo Lightcraft12 would, in principle, require no ablation fuel other than ambient air, in the atmosphere.Biparabolic design: laser light coming from below forms a ring focus under rim, propels craft via successive detonations in air.Outside atmosphere, the device would use solid ablatants located in rim.Flown to 72m in spin-stabilized flight, driven by a repetitively-pulsed, 10kW CO2 laser.Cm ranged from about 250N/MW for air to 900N/MW for Delrin solid propellant.Materials problems are challengingRezunkov ASLPE engine4Uses 6kW rep-pulse CO2 laserWire-guided flight in laboratoryGenerates 2N thrustPhoto: Courtesy Leik Myrabo12Myrabo, AIAA/SAE/ASME 18th Joint Propulsion Conference, Cleveland, OH (1982)
17 ORIONGround-based system causes ablation jet on near-Earth space debris targets, eventually lowering perigee until re-entry occurs13C. Phipps, AIP Conference Proceedings 318, (1994)
18 Direct Launch to LEOConnection between the charts: 3.3USD/MJ of laser light delivered at 5 flights per day. Is that reasonable14? Compare cost of wallplug energy on the ground (0.03USD/MJ).[14See Phipps & Michaelis, Laser and Particle Beams, 12(1), (1994)]Above: theoretical predictions for flight in vacuum. Laser launching facilitates frequent launches, diluting recurrent and sunk costs.Above: (•) flight simulation results for 1-m diameter craft laser-launched from ho = 30km in air compared to vacuum predictions at left.
19 Promise for the Future Timeframe Technology Problems to be Solved 1-2 yearsSpaceflights for Laser Plasma ThrusterORION system100k$ funding100M$ funding2-10 yearsLightcraft flights through atmosphere to LEOAblation of Lightcraft material5-10 years5kg payloads to LEOLEO to GEO transfer vehicleskW, N-thrust liquid-fuel enginesBuilding MW-class RP lasers & launch vehicles15-20 yearsLaunch to LEO with tonne payloadsInitial investment (multi-B$)
21 The Parameter yI would like to make this point very clear. Take a “drift Maxwellian”:1)2)3)4)≥1If M = u/cs = 1, and cs = (kT/mE)1/2 with = cp/cv =5/3, we have = 1.60Comment: forward peaking of most free, high-intensity laser ablation jets1 can give M≈2 and = 1.15, and we can take ≈ 1.[1See Kelly and Dreyfus, Nucl. Inst. Meth. B32, 341 (1988)