Z Pinch

1Conceptual 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.

2Team 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

3Z-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.

4Operation of a Z Pinch

Cathode

Anode

Hypersonic Nozzle

I

Gas Cylinder

Evacuated Chamber

5High Current Generates Intense

Magnetic Fields

I

B, Magnetic Flux

6Magnetic Fields Compress the

Plasma to X-Ray Temperatures

Ion Motion B

X-rays

7Plasma 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.

8Electrode 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

9Thruster Concept

Hypersonic NozzlesCathode

Anode

Z-Pinch

D-T Fuel

Secondary Fuel

And Radiation

Shield

MHD Generator

10

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

11

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

12

Engine Performance

Engine Performance as a function of liner mass

Design point picked based on mission needs

13

Nozzle Performance

Particle trajectory modeling required to estimate performance and correctly size nozzle.




14

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

15

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

16

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

17

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

18

Power Management System




Recharging for next pulse one of the major

technical challenges for pulsed fusion

19

Structural Analysis of Magnetic

Nozzle

Structural truss can handles stresses from pulsed fusion indefinitely.




Focal point of nozzle

20

Thermal Management System

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




21

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)

23

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 work




Z Pinch

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