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July 31, 2009

Photonic Propulsion and Fusion Work at Bae Institute

Young K. Bae demonstrated pure photonic propulsion by bouncing 10 Watt lasers between mirrors a few thousand times and generate 35 micronewtons of force.

Details on the photonic laser thruster demonstration.

Photonic Laser Thruster (PLT) is an innovative photon thruster that amplifies photon thrust by orders of magnitude by exploiting an active resonant optical cavity formed between two mirrors on paired spacecraft. PLT is predicted to be able to provide the thrust to power ratio (T/P) approaching that of conventional thrusters, such as laser ablation thrusters and electrical thrusters. Yet, PLT has the highest Isp of 3x10^7 sec, which is orders of magnitude larger than that of other conventional thrusters. We have demonstrated the photon thrust amplification in PLT for the first time. The T/P obtained with an OC mirror with R= 0.99967±0.00002 was 20±1 µN/W, and the maximum photon thrust obtained was 35 µN, resulting in an apparent photon thrust amplification factor of 2,990±150. Scaling-up of PLT is promising, and PLT is predicted to enable wide ranges of space endeavors. Low thrust PLTs may enable nanometer precision spacecraft formation for forming ultralarge space telescopes and radars, and provide economically viable solution to Fractionated Spacecraft Architecture, the System F-6. Medium thrust PLTs may enable precision propellantless orbit changing and docking. High thrust PLTs may enable propelling spacecraft at speeds orders of magnitude greater than that by conventional thrusters.



There are technical issues still to be overcome thermal limitation, optical absorption, and saturation of the laser gain media.



Near Term possibility: Photon tether formation flight (PTFF),with the maximum baseline distances greater than 10 km, 10-W Photon Laser Thruster (PLT) with a 0.999998 (500,000 reflections, better mirror than the actual demo) reflectance OC mirror would produce FT 33:5 mN, would enable a wide range of formation flying missions.









Far Term: Photon Laser Propulsion (PLP) application is in deep-space rapid-turnaround probing missions. L is the distance of the acceleration and M is the mass of the launched spacecraft.



If the scattering and absorption of the optical systems are negligible, with a 10-MW laser system, 0.999998 reflectance mirrors, and maximum velocity max 180 km/s accelerating for 1000 kilometers a 1 kilogram mass. At this velocity, the PLP spacecraft would transit the 100 million kilometers to Mars in less than a week.


Fusion work with Winterberg

Bae Institute proposes in a recent paper that the existence of Metastable innershell molecular state (MIMS) was experimentally discovered by Bae et al. in hypervelocity (v > 100 km/s) impact of nanoparticles. The decay of MIMS resulted in the observed intense soft x-rays in the range of 75–100 eV in agreement with Winterberg’s recent prediction.

MIMS can be used for generating super-intense x-ray beams with unprecedented high conversion efficiency from kinetic-energy to x-ray energy, over 40%. Such super-intense x-ray beams can make inertial confinement nuclear fusion more efficient and economically viable. Metastable Innershell Molecular State (MIMS) is a new high energy density matter quantum state. MIMS exists in matters compressed “suddenly” at pressures in excess of one hundred million atmospheres.


The super intense x-ray generation efficiency in % as a function of nanoparticle shock pressure in millions of atmospheres (Mbar). The excellent Arrhenius fit to the data indicates the existence of Metastable Innershell Molecular State (MIMS), a transient quantum state in highly compressed matter.



They propose that the proposed intense x-ray production with nanoparticle impact can be used to generate intense hard xrays.

Efficient x-ray generation from matters composed of heavy elements may not require the usage of nanoparticles and Dicke superradiance mechanism. Based on the experimental observation by Bae et al and present analyses, the kinetic energy per atom required for triggering the x-ray production mechanism is in the order of the
x-ray energy. For the 92U–92U pairs, the required velocity of 92U nanoparticles to achieve such threshold energy is ∼ 100 km/s, of which corresponding threshold pressure is ∼2 Gbar.

They propose that Metastable innershell molecular state (MIMS) can be readily created in “cold” compression with pressures in excess of 100 Mbar and that such “cold compression can be generated in the hypervelocity (v > 100 km/s) of nanoparticles, in which the collision/compression time scale (10–100 fs) is shorter than the ion–electron thermalization time scale (> 1 ps). Further, they propose here that the limited size of nanoparticles can increase the emission rate of MIMS x-rays owing to the Dicke superradiance mechanism. Their theory combined with the Winterberg’s recent prediction explains that the anomalous detector signals discovered by Bae et al. in hypervelocity (v > 100 km/s) impact of nanoparticles, such as clusters and biomolecules, resulted from the existence and optical decay of MIMS. The analysis of the experimental data resulted in the energy of intense soft xrays in the range of 75–100 eV in agreement with Winterberg’s prediction, and the conversion efficiency of 38% from the initial kinetic energy of nanoparticles to the x-ray radiation energy.


FURTHER READING
Friedwardt Winterberg has made major contribution to nuclear fusion theory and initiated the ideas that led to global positioning satellites.

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