Presentation on theme: "1 A Review of Laser Ablation Propulsion Claude Phipps 1, Willy Bohn 2, Thomas Lippert 3, Akihiro Sasoh 4, Wolfgang Schall 5 and John Sinko 6 1 Photonic."— Presentation transcript:
1 A Review of Laser Ablation Propulsion Claude Phipps 1, Willy Bohn 2, Thomas Lippert 3, Akihiro Sasoh 4, Wolfgang Schall 5 and John Sinko 6 1 Photonic Associates LLC, 200A Ojo de la Vaca Road, Santa Fe, New Mexico USA Phone/Fax: , 2 Bohn Laser Consult, Weinberg Weg 43, Stuttgart, Germany 3 Paul Scherrer Institut, CH5232 Villigen PSI, Switzerland 4 Department of Aerospace Engineering, Nagoya University, Chikusa-ku, Nagoya, Japan 5 DLR Institute of Technical Physics, Stuttgart, Germany (retired) 6 Micro-Nano GCOE, Graduate School of Engineering, Nagoya University, Chikusa-ku, Nagoya, Japan Advanced Laser Technologies 2009 Antalya, Turkey September 30, 2009
2 Contents 1. Benefits of laser ablation propulsion (LAP) 2. Scope of this review 3. History starting with pure photon propulsion 4. Pulsed laser ablation propulsion Operating range Vapor and plasma regime theory 5. Applications Laser plasma thruster (LPT) Laser-driven in-tube accelerator (LITA) Liquid-fueled laser-plasma engine Lightcraft Laser space debris mitigation (ORION) Direct launch to low earth orbit 6. Promise for the future
Benefits of LAP 1) Lower costs with laser launching. Todays cost of launching one kg into low Earth orbit (LEO) is equivalent to the cost of gold. Todays LEO launch costs Launch System Minimum Cost (k$/kg) Rockot10 Shuttle12 Athena 212 Taurus20 ISS, commercial22 Pegasus XL24 Long March CZ-2C30 Athena41 Greater than the price of gold! But it need not be so! [Myrabo Lightcraft flight, White Sands] Photo: Courtesy Leik Myrabo
Benefits of LAP 2) Lower Dead Mass Do not have to fly turbines, pumps, tanks, exhaust nozzles, etc., along with the payload 3) Variable Exhaust Velocity (crucial!) From chemical rockets up to and surpassing that of ion engines Accomplished by varying intensity on target (, A s ) Permits maximum efficiency flights 1,2 in which exhaust and flight velocity are matched, leaving exhaust particles with zero momentum 1 C. 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 Uchida, 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 30kN/m 2 demonstrated in the PALLC minithruster 3 5) High thrust to mass ratio 15kN/kg demonstrated in Russian ASLPE engine 4 6) High thrust efficiency 125% expected for kW laser thruster 5 This is possible due to exothermic fuels Not a trivial distinction for spacecraft 3 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 context Inertial confinement fusion except as a reference point Fundamental plasma physics theory » Coulomb explosions, LASNEX modeling, etc Photo courtesy Yuri Rezunkov (time exposure of flight in lab)
History in a Nutshell Fridrich Tsander, 1924: :Pure photon propulsion But C m = thrust / laser watt = 2/c = 6.7 mN/MW Wolfgang Möckel 1972:Basic theory of laser driven rockets Arthur Kantrowitz :Laser ablation propulsion (LAP) C m 100N/MW to 10kN/MW due to plume acceleration Leik Myrabo :Flight to 72m altitude in New Mexico desert Rezunkov :2N thrust demonstrated Tsander 6 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 C m = I / W=mv E /W = F/P 2) Specific ablation energy Q* = W/m 3) Exhaust velocity v E = C m Q* 4) Specific impulseI sp = I /(mg o ) = v E /g o 5) Mass usage rate 6) Ablation efficiency AB = W E /W = m v E 2 /(2W) = C m v E /2 7) Energy conservation where = /( 2 ) 1 is a parameter 8 that is often 1 (The C m v E product = 2.0 when AB = = 1, but cant be larger unless AB >1) [ 8 Phipps & Michaelis, Laser and Particle Beams, 12(1), (1994)] C m v E = C m I sp *g o = (2/ ) AB
Operating Range From water cannons nearly to photon propulsion! [References below can be found in the JPP review paper]
10 Terminology, contd Some ancillary relationships among LSP parameters: 8) Thrust efficiency T = eo AB 9) Fuel lifetime AB = g o 2 MI sp 2 /(2P AB ) [Severe penalty paid for I sp = 10s as in water cannons] Lots of thrust, but 10,000 times less AB than if I sp =1000s 10) Optimum coupling fluence opt = MJ/m 2 11) Ionization fraction where (Saha equation): i = 2n e /(n o + n e + n i ) Opt. Coupling Fluence vs.
Theory 12) Plasma regime model 9 : 13) Vapor regime model 10 : [In Eq. 12, A is mean atomic mass, Z is mean ionic charge state, = A/2[Z 2 (Z+1)] 1/3. In Eq. 13, = / o, o = thrust fluence threshold,T = transmissivity from laser to surface, = ablation layer absorption coefficient, = target solid density and = incident fluence] Plasma model was not meant to be valid as Z 0,, Vapor model was not meant to treat the plasma state Problem: how do we make the transition between the two models? 9 I sp 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)
Solution to the problem Vapor Plasma We use C m = [ i p p +(1- i ) p v ]/I = i C mp + (1- i ) C mv
Laser Plasma Thruster (Note: macro-LPT will not need T-mode) ms thruster (10mN, 250s) ns thruster (50 N, 3660s) See Phipps & Luke, reference 3.
LITA Laser in-tube Accelerator concepts of Sasoh 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 lasers 5 See Phipps, Luke and Helgeson, reference 5.
Lightcraft Myrabo Lightcraft 12 would, in principle, require no ablation fuel other than ambient air, in the atmosphere. 12 Myrabo, AIAA/SAE/ASME 18th Joint Propulsion Conference, Cleveland, OH (1982) 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 CO 2 laser. C m ranged from about 250N/MW for air to 900N/MW for Delrin solid propellant. Materials problems are challenging Rezunkov ASLPE engine 4 Uses 6kW rep-pulse CO 2 laser Wire-guided flight in laboratory Generates 2N thrust Photo: Courtesy Leik Myrabo
17 ORION Ground-based system causes ablation jet on near-Earth space debris targets, eventually lowering perigee until re-entry occurs 13 C. Phipps, AIP Conference Proceedings 318, (1994)
Direct Launch to LEO 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 h o = 30km in air compared to vacuum predictions at left. Connection between the charts: 3.3USD/MJ of laser light delivered at 5 flights per day. Is that reasonable 14 ? Compare cost of wallplug energy on the ground (0.03USD/MJ). [ 14 See Phipps & Michaelis, Laser and Particle Beams, 12(1), (1994)]
19 Promise for the Future TimeframeTechnologyProblems to be Solved 1-2 years Spaceflights for Laser Plasma Thruster ORION system 100k$ funding 100M$ funding 2-10 years Lightcraft flights through atmosphere to LEO Ablation of Lightcraft material 5-10 years 5kg payloads to LEO LEO to GEO transfer vehicles kW, N-thrust liquid-fuel engines Building MW-class RP lasers & launch vehicles years Launch to LEO with tonne payloads Initial investment (multi-B$)
21 The Parameter I would like to make this point very clear. Take a drift Maxwellian: 1) 2) 3) 4) 1 If M = u/c s = 1, and c s = ( kT/m E ) 1/2 with = c p /c v =5/3, we have = 1.60 Comment: forward peaking of most free, high-intensity laser ablation jets 1 can give M2 and = 1.15, and we can take 1. [ 1 See Kelly and Dreyfus, Nucl. Inst. Meth. B32, 341 (1988)