conceptual design of a z-pinch fusion propulsion systemradams).pdf · decade module ii •500 kj...

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Conceptual Design of a Z-Pinch Fusion

Propulsion System

Advanced Concepts Office

George C. Marshall Space Flight Center

National Aeronautics and Space Administration

Robert Adams, Ph.D.

2

Team Members

• Polsgrove T., Fincher, S., Adams, R. – NASA (MSFC)

• Fabisinski, L. - International Space Systems, Inc.

• Maples, C. - Qualis Corporation

• Miernik, J., Statham, G. - ERC, Inc.

• Cassibry, J., Cortez, R., Turner, M. - UAHuntsville

• Santarius, J. - University of Wisconsin

• Percy, T. - SAIC, Inc.



ED04/Advanced Concepts Office

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Z-Pinch Fusion: Background

• Nuclear weapon x-rays are simulated through Z-Pinch

phenomena.

• New developments in multi-keV plasma radiation

sources are progressing to thermonuclear fusion

temperatures*

• Such technology could be applied to develop advanced

thruster designs that promise high thrust/high specific

impulse propulsion

• This project would develop a conceptual design for such

a thruster.

*Velikovich, A. L., R. W. Clark, J. Davis, Y. K. Chong, C. Deeney, C. A. Coverdale, C. L. Ruiz, et al. 2007, Z-pinch plasma neutron sources,

Physics of Plasmas 14, no. 2: 022701. doi:10.1063/1.2435322.

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Operation of a Z Pinch

Cathode

Anode

Hypersonic Nozzle

I

Gas Cylinder

Evacuated Chamber

5

High Current Generates Intense

Magnetic Fields

I

B, Magnetic Flux

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Magnetic Fields Compress the

Plasma to X-Ray Temperatures

Ion Motion B

X-rays

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Plasma Instability

• Rayleigh-Taylor is most

deleterious effect

preventing success,

can be overcome with

tailored density profile*

*Velikovich, Cochran, and Davis, Phys. Rev. Let. 77(5) 1996.

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Electrode Erosion

• Coupling electrical energy to plasma– Directly coupled devices lead to erosion

– All susceptible to x-ray radiation and neutron damage

• Potential workarounds– Allow electrodes to erode!

– Consider inductively coupled techniques

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Thruster Concept

Hypersonic NozzlesCathode

Anode

Z-Pinch

D-T Fuel

Secondary Fuel

And Radiation

Shield

MHD Generator

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Z-pinch Design

• Annular nozzles

with Deuterium-

Tritium (D-T) fuel in

the innermost

nozzle

• Lithium mixture

containing Lithium-

6/7 in the outermost

nozzle.

• The D-T fuel and

Lithium-6/7 mixture

acts as a cathode

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Z-pinch modeling

• Treat Z-pinch as Otto cycle

– Process 1-2: Isentropic compression

– Process 2-3: Constant volume heat

addition

– Process 3-4: Isentropic expansion

– Process 4-1: Constant volume heat

rejection

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Engine Performance

• Engine Performance as a function of liner mass

• Design point picked based on mission needs

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Nozzle Performance

• Particle trajectory modeling required to estimate

performance and correctly size nozzle.




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0.0%

5.0%

10.0%

15.0%

20.0%

25.0%

30.0%

35.0%

40.0%

45.0%

50.0%

0 20000 40000 60000 80000 100000 120000

Mission Delta-V (m/s)

Paylo

ad

% (

Paylo

ad

Mass /

IM

LE

O)

Mars Round Trip (90 Days One Way)

Mars Round Trip (30 Days One Way)

Jupiter Round Trip

One Way Trip to Mars (180 Days One Way)

One Way Trip to Mars (90 Days One Way)

Traditional Chemical

Propulsion

Z-Pinch Fusion

Propulsion

Missions to Mars, Jupiter, and Beyond can be achieved

with significantly reduced trip times when

compared to state of the art chemical propulsion

90 day transfer

from Earth to

Mars

Missions Enabled

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Mission Analysis

Mars 90 Mars 30 Jupiter 550 AU

Outbound Trip Time (days) 90.2 39.5 456.8 12936

Return Trip Time (days) 87.4 33.1 521.8 n/a

Total Burn Time (days) 5.0 20.2 6.7 11.2

Propellant Burned (mT) 86.3 350.4 115.7 194.4

Equivalent DV (km/s) 27.5 93.2 36.1 57.2




Figure 4.1 Mars 90 Day Transfer Trajectories

Mars Orbit

Earth Orbit

Transfer Traj Orbit

Transfer Trajectory

Mars Orbit

Earth Orbit

Transfer Traj Orbit

Transfer Trajectory

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Vehicle Configuration

Subsystem Mass (kg)

Payload 150,000

Structures 54,600

Main Propulsion 95,138

RCS 586

Thermal 77,164

Power 16,480

Avionics 389

Total Dry Mass 394357

30% MGA 73,307

Total Mass 467,664

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Thrust Coil Configuration

• FLiBe protects thrust and seed coils from thermal flux and

other radiation.




Seed Field

Superconductor

and LN2

coolant channelKapton

Insulator

Seed Coil

Load

Structure

Radiant Heat

Shield

Seed Field

Coil Housing

Evacuated

Region Molten mixture of lithium fluoride

(LiF) and beryllium fluoride (BeF2)

[FLiBe].

Thrust Coil

Load

Structure

Thrust Coil

Conductor

Diagram intended to illustrate the general

composition of the rings that comprise the nozzle.

Dimensions and aspect ratio to be determined

after detailed structural analysis.

Neutron

protection/cooling

channelZirconium diboride

(ZrB2) ceramic shell

Direction

of Fusion

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Power Management System




Recharging for next pulse one of the major

technical challenges for pulsed fusion

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Structural Analysis of Magnetic

Nozzle

• Structural truss can handles stresses from pulsed fusion

indefinitely.




• Focal point of

nozzle

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Thermal Management System

• Radiators operate at 300 K, 800 K and 1400 K.




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Avionics Suite




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DECADE Module II

• 500 kJ pulsed power facility

• Last prototype built before DECADE construction

• Defense Threat Reduction Agency– Nuclear Weapons Effects (NWE)

– Plasma Radiation Sources (PRS)

• Good working order

• Capable of >1 TW instantaneous

power (about 6% of world's

electrical power consumption)

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Pulsed Fusion Facility

• DM2 Utilization Arrangements – L3 Communications, Pulsed Science Division

– Boeing

– Oak Ridge National Labs

• Other fusion collaborations– LANL

– HyperV Corp.

– Univ. of New Mexico

• Expected Capabilities– 500 ns pulse, 2 MA current

– 1 keV, 1025 /m3 plasma state

– Effective dwell time of ~100 nsAerophysics

lab

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Summary

• No showstoppers found for this technology– Preliminary analytical results are promising

– The technology development required for this propulsion system is

achievable on a reasonable timescale given sufficient resources.

• Z-pinch has potential for a number of missions of interest– Reusable vehicle that recaptures in Earth Orbit does round trips to Mars

– Interstellar precursor missions

– Crewed Missions to other solar system targets

• Opportunity to create new facility to explore z-pinch and

other pulsed fusion concepts– Looking for funding to move module to MSFC for installation

– Completed facility would allow proof of principle experiments on pulsed fusion

concepts.

• Our team thanks the NASA Innovative Programs and

Partnerships Program for funding this workNational Aeronautics and Space Administration



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