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Phipps C.,Photonic Associates LLC | Birkan M.,U.S. Air force | Bohn W.,BohnLaser Consult | Eckel H.-A.,German Aerospace Center | And 7 more authors.
Journal of Propulsion and Power | Year: 2010

LASER ablation propulsion (LAP) is a major new electric propulsion concept in which an intense laser beam (pulsed or continuous wave (CW)) strikes a condensed-matter surface (solid or liquid) and produces a jet of vapor or plasma. The laser system involved in LAP may be remote from the propelled object. Pulsed laser ablation can be used into a thrust chamber, the light must pass through absorbing ablation products. An important factor in the improvement of performance figures of merit and of ablation efficiency is choosing an appropriate propellant. For laser intensities high enough to form a fully ionized plasma, the impulse delivered to a target by a laser pulse can be predicted with factor-of-2 accuracy using relationships. The first practical space application of LAP is already built, tested, and awaiting a flight, the laser-plasma thruster. Direct launch into LEO (low earth orbit) with large payloads will be possible if the investment is put in place now.


Liedahl D.A.,Lawrence Livermore National Laboratory | Rubenchik A.,Lawrence Livermore National Laboratory | Libby S.B.,Lawrence Livermore National Laboratory | Nikolaev S.,Lawrence Livermore National Laboratory | Phipps C.R.,Photonic Associates LLC
Advances in Space Research | Year: 2013

Among the approaches to the proposed mitigation and remediation of the space debris problem is the de-orbiting of objects in low Earth orbit through irradiation by ground-based high-intensity pulsed lasers. Laser ablation of a thin surface layer causes target recoil, resulting in the depletion of orbital angular momentum and accelerated atmospheric re-entry. However, both the magnitude and direction of the recoil are shape dependent, a feature of the laser-based remediation concept that has received little attention. Since the development of a predictive capability is desirable, we have investigated the dynamical response to ablation of objects comprising a variety of shapes. We derive and demonstrate a simple analytical technique for calculating the ablation-driven transfer of linear momentum, emphasizing cases for which the recoil is not exclusively parallel to the incident beam. For the purposes of comparison and contrast, we examine one case of momentum transfer in the low-intensity regime, where photon pressure is the dominant momentum transfer mechanism, showing that shape and orientation effects influence the target response in a similar, but not identical, manner. We address the related problem of target spin and, by way of a few simple examples, show how ablation can alter the spin state of a target, which often has a pronounced effect on the recoil dynamics. © 2013 COSPAR. Published by Elsevier Ltd. All rights reserved.


Phipps C.,Photonic Associates LLC | Lander M.,UES, Inc.
AIP Conference Proceedings | Year: 2011

Orbital debris in low Earth orbit (LEO) are now sufficiently dense that the use of space is threatened by runaway collision cascading. A problem predicted more than thirty years ago, the threat from debris larger than about 1cm is now a reality that we ignore at our peril. The least costly, and most comprehensive, solution is Laser Orbital Debris Removal (LODR). In this approach, a high power pulsed laser on the Earth creates a laser-ablation jet on the debris object's surface which provides the small impulse required to cause it to re-enter and burn up in the atmosphere. The LODR system should be located near the Equator, and includes the laser, a large, agile mirror, and systems for active detection, tracking and atmospheric path correction. In this paper, we discuss advances that have occurred since LODR was first proposed, which make this solution to the debris problem look quite realistic. © 2011 American Institute of Physics.


Phipps C.R.,Photonic Associates LLC | Bonnal C.,Launcher
Acta Astronautica | Year: 2016

Among the problems raised by the presence of debris in Earth Orbit, the question of large derelict satellites in Geostationary Orbit (GEO) is of major importance. More than 1000 defunct GEO satellites cruise in the vicinity of this unique orbit and pose the question of orbital slot availability. It is proposed to use lasers in GEO to reorbit the large debris in the graveyard zone, some 300 km above GEO. The principle of orbital transfer by laser ablation is recalled, and two different methods are described. These lasers can also serve for small debris deorbiting and large debris nudging in Low Earth Orbit (LEO). Technical details are provided, as well as a preliminary mass budget. © 2015 IAA.


Phipps C.,Photonic Associates LLC | Sinko J.,Nagoya University
AIP Conference Proceedings | Year: 2010

Previously, Phipps, et al. developed a model that permitted laser ablation impulse predictions within a factor of two over an extremely broad range of pulse durations and wavelengths in the plasma regime. This model lacked the ability to predict the intensity for optimum impulse generation. For the lower-intensity vapor regime, below the plasma transition, Sinko developed a useful, fluence-dependent model which predicts impulse delivered for pulsed lasers on polymers at a specific wavelength. Phipps subsequently developed an alternate model which treats elemental solids in the vapor regime, that only requires knowledge of basic material parameters and vapor pressure vs. temperature data. These data, except for optical absorptivity, are wavelength-independent. A simple technique combines either vapor model with the plasma model to form a complete model that moves smoothly through the vapor to plasma transition. In this paper, we apply these models to show the optimum momentum coupling fluence on target, at the transition from the vapor to the plasma regimes, for aluminum (a typical debris material) and polyoxymethylene (representing polymeric debris). The application of this work is the ORION laser space debris mitigation concept. This is an improvement over previous work, in which this optimum was only estimated from the plasma ignition threshold. We present calculations showing how impulse delivered to debris targets in the ORION concept varies with pulse duration, at an optimum fluence determined by nonlinear optical effects in the Earth's atmosphere. © 2010 American Institute of Physics.


Sinko J.E.,Nagoya University | Phipps C.R.,Photonic Associates LLC | Sasoh A.,Nagoya University
AIP Conference Proceedings | Year: 2010

Laser ablation vaporization models have usually ignored the spatial dependence of the laser beam. Here, we consider effects from modeling using a Gaussian beam for both photochemical and photothermal conditions. The modeling results are compared to experimental and literature data for CO2 laser ablation of the polymer polyoxymethylene under vacuum, and discussed in terms of the ablated mass areal density and momentum coupling coefficient. Extending the scope of discussion, laser ablative impulse generation research has lacked a cohesive strategy for linking the vaporization and plasma regimes. Existing models, mostly formulated for ultraviolet laser systems or metal targets, appear to be inappropriate or impractical for applications requiring CO2 laser ablation of polymers. A recently proposed method for linking the vaporization and plasma regimes for analytical modeling is addressed here along with the implications of its use. Key control parameters are considered, along with the major propulsion parameters needed for laser ablation propulsion modeling. © 2010 American Institute of Physics.


Phipps C.,Photonic Associates LLC
AIP Conference Proceedings | Year: 2010

Other papers in this conference discuss the ORION concept for laser space debris mitigation. An alternative approach to removing space debris nicknamed "Catcher's Mitt" has been proposed. In this concept, a block of low density solid material is placed in a precessing, elliptical, near-equatorial orbit to sweep out near-Earth space between about 400km and 1100km altitude where the hazardous debris objects reside. The concept could work by vaporizing or trapping the objects, or slowing them enough for re-entry on passing through the "mitt." To compete with ORION, an alternative must intercept 300k objects in two years. We demonstrate two difficulties with the "mitt" idea. The first of these is that even if it is made of aerogel with 1mg/cm 3 density, the required mass is about 2MT. The second problem is that an elliptical mitt orbit covering the 400 - 1100 km debris altitude range would suffer ram pressure that would have to be compensated by a 10kN-thrust engine operating continuously for the mission duration, which is assumed to be two years. © 2010 American Institute of Physics.


Phipps C.,Photonic Associates LLC
AIP Conference Proceedings | Year: 2010

It is now well-established that a Near-Earth Object (NEO) in the 5 to 10-km size range extinguished the dinosaurs. Although such events have an impact interval on the order of 100M years, a method of rapid response to such a threat is crucial, since warning time is short. Objects in the 0.1 to 1 km size range may not be detected before approaching within 1 to 10 astronomical units (AU) of Earth and, since their approach velocity may be 30-60 km/s, that situation leaves 100 - 300 days to respond. Although the most frequently suggested response to such a threat is a standoff nuclear detonation, physically delivered to the NEO, this paper finds significant advantages in retargeting, probability of success and even precise target location are possible with a high power laser alternative. Assuming a momentum coupling coefficient Cm = 3.5 dyn-s/J and detection at 6.3AU, a 770kW repetitive pulse 355nm laser (f = 1.7 ppm with 27MJ, 10ps pulses) will deflect a 200-m-diameter icy NEO sufficiently to avoid collision. The focusing mirror would need to be manufactured on the Moon. © 2010 American Institute of Physics.


Phipps C.,Photonic Associates LLC
International Journal of Aerospace Innovations | Year: 2011

In this paper, we address the problem of predicting p(I), the variation of surface ablation pressure vs. incident pulsed laser intensity I, from the onset of ablation through the transition to its mediation by laser-induced plasma in vacuum. Despite its simplicity, the recently published approach of Sinko and Phipps [1] to this problem describes momentum coupling for many laser-target interactions quite well, for one material at a single wavelength where the ablation fluence threshold is clearly defined. Alternatively, if vapor pressure vs. temperature data p(T) is available for a material, e.g., using the SESAME tables, a different model can be used. In addition to the p(T) data, this model only requires knowledge of basic parameters for the material, such as specific heat, thermal conductivity, optical absorptivity, atomic weight, and its ionization state energies and their partition functions. Since all these parameters, except for optical absorptivity, are independent of laser wavelength, it is possible to calculate a material's mechanical impulse response to pulsed laser irradiation with broad applicability. We show that our model agrees with published data on momentum coupling in aluminum from KrF to CO 2 laser wavelengths to within a factor of two.


Phipps C.R.,Photonic Associates LLC
Acta Astronautica | Year: 2014

Collisions among existing Low Earth Orbit (LEO) debris are now a main source of new debris, threatening future use of LEO space. Due to their greater number, small (1-10 cm) debris are the main threat, while large (>10 cm) objects are the main source of new debris. Flying up and interacting with each large object is inefficient due to the energy cost of orbit plane changes, and quite expensive per object removed. Strategically, it is imperative to remove both small and large debris. Laser-Orbital-Debris-Removal (LODR), is the only solution that can address both large and small debris. In this paper, we briefly review ground-based LODR, and discuss how a polar location can dramatically increase its effectiveness for the important class of sun-synchronous orbit (SSO) objects. With 20% clear weather, a laser-optical system at either pole could lower the 8-ton ENVISAT by 40 km in about 8 weeks, reducing the hazard it represents by a factor of four. We also discuss the advantages and disadvantages of a space-based LODR system. We estimate cost per object removed for these systems. International cooperation is essential for designing, building and operating any such system. © 2013 IAA Published by Elsevier Ltd. All rights reserved.

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