Application of Recommended Design Practices for Conceptual Nuclear Fusion Space Propulsion Systems

Williams, Craig H.

doi:10.2514/6.2004-3534

Cited by 13 publications

(8 citation statements)

References 13 publications

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“…There are many pre-conceptual point designs for fusion rocket cores, ranging from generic fusion rocket systems studies [11,12], to levitated dipoles [13], to mirror machines [14], to field reversed configurations [15], and magnetized target fusion [8,16]. Even ST tokamaks [17] and laser fusion sources [18] have been suggested (although present incarnations aren't reactors, and even so, are much too massive).…”

Section: Fusion's Unique Applicationmentioning

confidence: 99%

“…Most prior works [8][9][10][11][12][13][14][15][16][17][18] considering the need for fusion rocket engines have focused on manned exploration of the solar system, the large distances involved, and in particular, for the need to get people to Mars [19] or Jupiter [20] quickly enough so that health risks for crews are minimized during long duration missions. However as numerous events have shown, from the Cretaceous-tertiary extinction to the recent meteorite explosion over Chelyabinsk, the solar system can be a dangerous place.…”

Section: Why Does Our Civilization Need Faster Spacecraft? Planetary mentioning

confidence: 99%

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A New Vision for Fusion Energy Research: Fusion Rocket Engines for Planetary Defense

et al. 2015

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We argue that it is essential for the fusion energy program to identify an imagination-capturing critical mission by developing a unique product which could command the marketplace. We lay out the logic that this product is a fusion rocket engine, to enable a rapid response capable of deflecting an incoming comet, to prevent its impact on the planet Earth, in defense of our population, infrastructure, and civilization. As a side benefit, deep space solar system exploration, with greater speed and orders-of-magnitude greater payload mass would also be possible.The US Department of Energy's magnetic fusion research program, based in its Office of Science, focuses on plasma and fusion science [1] to support the long term goal of environmentally friendly, socially acceptable, and economically viable electricity production from fusion reactors [2]. For several decades the US magnetic fusion program has had to deal with a lack of urgency towards and inconsistent funding for this ambitious goal. In many American circles, fusion isn't even at the table [3] when it comes to discussing future energy production. Is there another, more urgent, unique, and even more important application for fusion? Fusion's Unique ApplicationAs an on-board power source and thruster for fast propulsion in space [4], a fusion reactor would provide unparalleled performance (high specific impulse and high specific power) for a spacecraft. To begin this discussion, we need some rocket terminology. Specific impulse is defined as I sp ¼ v e =g, where g is the usual Earth's gravitational acceleration constant and v e is the rocket propellant's exhaust velocity. The rocket equation, M f /M o = exp (-DV/v e ), allows us to relate the final mass M f of the rocket divided by its initial mass M o , to the change in velocity DV that it is capable of achieving. The rocket requires a power source with an output power P = aM s , where we define a to be the specific power (W/kg), and M s as the mass of the power supply (including the power conditioning, structures, and any waste heat radiators).Today's best chemical rockets produce propellant exhaust velocities (v e ) up to 4.5 km/s. Fission (nuclear thermal) rocket engines [5] could roughly double that, to about 8.5 km/s (\ eV/amu temperature equivalent), constrained by material limits [6]. Electrically driven thrusters [7] are already quite efficient and have higher propellant exhaust velocities (corresponding to *5 eV/ amu) but are usually limited in power resulting in low thrust, and are driven by limited electrical power/energy sources (photovoltaic or radioisotope). Development of high power, high thrust plasma thrusters has not been a

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Section: Fusion's Unique Applicationmentioning

confidence: 99%

Section: Why Does Our Civilization Need Faster Spacecraft? Planetary mentioning

confidence: 99%

A New Vision for Fusion Energy Research: Fusion Rocket Engines for Planetary Defense

et al. 2015

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“…Values for η can vary widely, and the performance of the system will be more accurately represented through an integrated numerical simulation of the compression, burn, and expansion of the fusion plasma in the magnetic nozzle. However, for these preliminary estimates we assume a value of η ≈ 0.7, consistent with recommended practice [29]. The specific impulse (Isp) of the system can then be estimated using:…”

Section: Estimating System Performancementioning

confidence: 96%

Preliminary Analysis of the Gradient Field Imploding Liner Fusion Propulsion Concept

LaPointe

Cassibry

Adams

et al. 2018

2018 Joint Propulsion Conference

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The advancement of human deep space exploration requires the continued development of energetic inspace propulsion systems, advancing from current chemical engines to nuclear thermal rockets to future high energy concepts such as nuclear fusion. This paper presents the initial results of a NASA Innovative Advanced Concepts (NIAC) Phase I study funded to investigate the feasibility of a new pulsed fusion propulsion concept based on the rapid implosion of a fuel target injected at high velocity into a strong stationary magnetic field. The proposed concept takes advantage of the significant advances in terrestrial magneto-inertial fusion designs while attempting to mitigate the most common engineering impediments to in-space propulsion applications. A semi-analytic numerical model used to estimate target compression physics and energy release is presented, leading to estimates for engine performance. A preliminary vehicle design concept is outlined, and representative trajectory analyses for rapid Mars and Saturn missions are provided. The paper concludes with an overview of proposed next steps for theoretical and experimental validation of the concept.

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“…With input from the participants of the TIMs and members of the NFFPTC, they produced a peer-reviewed industry standard on fusion propulsion system in 2004 entitled "Recommended Design Practices for Conceptual Nuclear Fusion Space Propulsion Systems" [56]. Williams [57] provided a simplified form of the report with good examples of technological extrapolations. Adams and Cassibry [58] revised some of the previous fusion concepts, followed by a similar paper by Bruno and Romanelli [59] in 2006 clearly showing significantly higher power-to-mass ratios of the PJMIF concept.…”

Section: Other Effortsmentioning

confidence: 99%

Case and Development Path for Fusion Propulsion

Cassibry¹,

Cortez²,

Stanić³

et al. 2015

Journal of Spacecraft and Rockets

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This paper discusses the importance of fusion propulsion for interplanetary space travel, illustrates why the magnetoinertial fusion parameter space may facilitate the most rapid, economic path for development, justifies the choice of pulsed Z pinch, and provides a potential development path leading up to a technical readiness level 9 system. Round trips of less than one year to Mars are only possible using fusion propulsion systems. Such a system will require an onboard nuclear fission reactor for reliable startups, and so fission and fusion developments for space are mutually beneficial. The paper reviews the more than 50 year history of fusion research and summarizes results from a recent study of the fusion parameter space for terrestrial power, which suggests magnetoinertial fusion can provide the smallest, most economical approach for a fusion propulsion system. Emerging experimental data and theory show pulsed Z-pinch fusion solves some of the most deleterious instabilities and scales to fusion breakeven within reach of current pulsed power facilities. The paper illustrates a potential development path to a technical readiness level 9 flight system, starting from an assumed technical readiness level 2 for the current state of fusion propulsion. Nomenclature a = acceleration, m∕s 2 g 0 = gravitational acceleration at Earth's surface, m∕s 2 J = mission difficulty parameter, m 2 ∕s 3 k = ratio of tank to propellant mass m = mass, kg _ m = mass flow rate, kg∕s N = total number of stages, number of fusion reactions n = number density P = power, W R = distance traveled, m T = total trip time and time, s t = time, s V = reacting volume, m 3 v j = jet or exhaust velocity, m∕s Y = fusion energy yield, J α = propulsion system specific mass, kg∕W β = mission type multiplication factor γ = ratio of propulsion system to initial mass of nth stage Δv = velocity increment, m∕s λ = payload mass fraction τ = characteristic time, s Subscripts burn = propulsive burn c, coast = unpowered coasting conf = confinement d = dwell, as in dwell time τ d f = final fus = fusion jet = jet, as in for jet power P jet n = number of the stage opt = optimum p = propulsion time pay = payload pn = propulsion time for nth stage (as in for T pn ) pr = propellant ps = propulsion system t = tank 0 = initial 1, 2 = dummy subscripts indicating different species

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Application of Recommended Design Practices for Conceptual Nuclear Fusion Space Propulsion Systems

Cited by 13 publications

References 13 publications

A New Vision for Fusion Energy Research: Fusion Rocket Engines for Planetary Defense

A New Vision for Fusion Energy Research: Fusion Rocket Engines for Planetary Defense

Preliminary Analysis of the Gradient Field Imploding Liner Fusion Propulsion Concept

Case and Development Path for Fusion Propulsion

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