Inertial confinement fusion (ICF) utilizing an antiproton catalyzed hybrid fission/fusion target is discussed as a potential energy source for interplanetary propulsion. A proof-of-principle experiment underway at Phillips Laboratory, Kirtland AFB and antiproton trapping experiments at CERN, Geneva, Switzerland, are presented. The ICAN propulsion concept is described and results of performance analyses are reviewed. Future work to further define the ICAN concept is outlined

Chakrabarti, Suman

Chiang, Pi-Ren

Dailey, James

Lewis, Raymond A.

Newton, Richard

Smith, Gerald A.

Werthman, W. Lance

English

NASA Technical Reports Server

N95. 70881
ANTIPROTON CATALYZED MICROFISSION/FUSION PROPULSION
Pi-Ren Ch/ang, Raymond A. I_awisand C,-eraldA. Smith
Department of Physics
and
Richard Newton
Depm_ment of Nuclear Engineoring
and
James Dailey and W. Lancc W©rthman
Department of Aerospace Engineering
and
Suman Chakrabarti
Department of Mechanical Engineering
PENNSYLVANIA STATE UNIVERSITY
303 Osmond Laboratory, University Park, PA 16802
ABSTRACT
Inertial confinement fusion tIC'F) utilizing an antiproton catalyzzd hybrid fission/fusion
target is discussed as a potential energy source for interplanetary propulsion. A proof-of-principle
experiment underway at Phi_ips Laboratory, Kirtland AFB, and antiproton trapping _ents at
CEILN, Geneva, Switzerland, are presented. The ICAN propulsion concept is described and
results of performance analyses are reviewed. Future work to further define the ICAN concept is
outlined.
I. INTRODUCTION
Inertial confinement fusion tIC'F) can provide thrust and high Isp for propulsion
applications from plasma created in anliproton-catalyzed microexplosions. The antiproton induced
ignition of fission reactions under conditions of high compression has been described previously
(T,cwh 1991). Here wc provide an ovcrview of th¢ full miorofmsion/fi_ion concept, including a
proof-of-principle experiment at the Phillips Laboratory to demonstrate _oal
anfiproton-catalyzed microfmsion. Recent advances made by our group in the trapping of
antiprotons are reviewed as well. The ICAN propulsion concept is discussed with regard to its
features and performance, and our future work is outlined.
IL ANTIPROTON-CATALYZED MICROFISSION/IcUSION
In 1992 large fission andnculron yields from antiproton annihilationat rest in a natural
uranium target were observed (Chen ctal. 1992). Calculations indicate that short bursts of
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rantiprotons could induce temperatures of several kcV in a small compressed pellet. These
conditions are appropriate for ignition of a hydrogen fusion bum within the microsphere. Targets
with yields up to 100 GJ have been considered (Kanzlciter 1991). Compression is provided by
light ion beams, such as from PBFA-2 ('VanDcvender and Cook 1986).
A proof of principle experiment at the SHIVA Star facility at the Phillips Laboratory,
Kirtland AFB, is underway to demonstrate subcrifical neutron multiplication due to antiproton
fission in targets compressed to 10-40 Mbar pressure. Antiprotons are released from a Penning
trap storage device, accelerated to 1.2 MeV by a radiofrequeney quadrupolc (RFQ), and focused
onto the compressed target inside and imploding solid liner driv_a by the SHI-v'A Star capacitor
bank. Figure 1 shows a close up of the target region, indicating the liner moving in rapidly and
compressing a hydrogen working fluid. A short 50 ns burst of antiprotons ignites the target as it
reaches peak compression.
9.6,-,,,
Figure 1. Solid Liner during Compression Cycle
HI. ANTIPROTON TRAPPING EXPERIMENTS
In collaboration with the P-15 group at Los Alamos National Laboratory (Holzschciter ©t.
aL, 1993), in July, 1993 w© trapl_ up to 721,000 anfiprotons from single beam shots at the Low
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Encr_ Antiproton Ring (I_E._.) at CERN. Fi_!r¢ 2 shows the Catcher Trap and transfer optics to
the Portable Trap. With improved vacuum, using mulfipulse injection and electron cooling in the
catcher trap we hope to trap and confine several miUiion anfiprotons before the end of 1994.
(a)
PS200 Catcher Trap (b) Antiproton Transfer Section
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Beam I_ X OxfordMagnet [7]
,,,c7O V ...J .../= m"
' / a-ll_.==X/ vo, 1/11 '-=
/ C4dl Baffles Scin_ill_ ators ScintJllato= _'_
NE110 Sc_nl_llatot 14 5-8
Catcher Trap Portable Trap
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Figure 2. Sch¢matics of (a) Catcher Trap and (b) Transfer Optics to the Portable Trap
IV. ICAN PROPULSION SYSTEM
The ICAN propulsion cone, opt cn'dsioned by our group is a deriva_'e of the h,_EDUSA
canopy (:oncept proposed by Solcm (1994), which is itself a variant of the ORION pusher plate
system (Augenstcin lYYl). In the ICAN concept, a large, hemispherical canopy two km in radius
is used to intercept debris from the explosion, transferring its momentum to the spacecraft via the
expansion and contraction of the canopy, which serves as the shock absorber necessary to smooth
out the acceleration. A detailed version of the canopy is shown in Figure 3, where we have used
titanium for the canopy because of its high operating temperature attd tensile strength.
The principle concerns associated with the ICAN system are momentum transfer to the
canopy tTom the hi# energy, propellant ions, along with the associated pertbrmancc and spuRcring
damage, the radiation damage caused by neutrons and x-rays reradiated by the expanding
propellant, and canopy heating. To asset us in investigating these issues, several computer codes
have been devclop¢d to simulate ¢ncrlD" release in the mic,rofissiorv'fusion target, absolption by the
propellant, and _ and radiation transport mechanisms in the expanding propellant. Canopy
damage and momentum transter are evaluated tLsing the "I'RIM spuRoring code (Biersack and
Eckstein, 1994).
We have chosen as a prototypical target one which rdeases 95 GJ of energy. This energ3'
is produced in a target consisting of a bout 1.0 g of nuclear fuel. The nuclear fuel is in a molar
ratio of9:l ofDT:U. Initi.,dly, the proportions of energy produt:¢d in the target arc 83% radiation,
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at initial firing
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Figure 3. ICAN Canopy Structure
15% neutron kinetic energy, and 2% random ion and electron kinetic energy. A high Z propellant,
lead, was chosen due to its high absorption cross-section v,ith respect to the radiation generated by
•,.heICAN u_ct
Accurate simulation of the propellant expansion process following the deposition of this
energy requires a sophisticated model, including an accurate equation-of-state, a radiation transport
model, and a thermal conduction model. Our Plasma Propulsion Dynamics (PPDYN) code
utilizes a single-temperature radiation model in a one-dimensional MttD code to determine the
amount of energy deposited in the propellant. Analysis of the propellant performance yi¢Ide, d the
thrust and Isp curves shown in Figure 4, as a function of the propellant mass per shot. A clear
tradeoff ¢xim between thrust and Isp, which plays a significant role in mission analysis.
V. FLrrURE WORK
We are presently working to expand the capabilities of our plasma propulsion dynamics
code to allow analysis of alternate propellants and mixtures of propellants in an effort to enhance
performance and decrease canopy damage. In addition, we have begun analyzing various mission
scenarios which utilize the high-Isp, low thrust ICAN system. Alternative canopy slructures and
materials also need to be considered in order to minimize sputtering damage and maximize system
p_fol'lllance.
i01
12000
11000
10000
9000
8000
f
7000
0
trigt 4.
I'''1 1 • I 100
-- -- - Average Thrust (kN) .-
f
/
/
/
''|litl,=,l,,,l,.,
8O
6O
40
20
200 400 600 800 1000
Mass Pb/shot (g)
Thrust and Isp vs. Propellant Mass at 1 Hz F'ning Rate
VI. ACKNOWLEDGMENTS
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This work is s,pported in part by AFOSR, Jet Propulsion Laboratory, NSF, Penn State
Center for Space Propulsion Engineering, grant #NAGW-1356 (suppL8), and Rocketdyne
Division, Rockwell International Corporation.
VII. REFERENCES
Augcxuteflt, B.W. (1991) "Some Aspects ofhttemtdlar Space Explolation-New Orion Systems,
Early Precursor Missions", flAA-91-716, 42nd Congress of the International Astronautical
Fed=ration, Oct. 5-11, 1991, Montreal, Canada.
Biersack, J.P., and W. Eckstein (1984) Appl. Phys. A34: 73.
Chcn, B., T.A. ,_amstrong P.A. Lcg_ R. Newton, G.A. Smith, J.P.IBocquet, F. Malek, H.
Nifenocker,M.Maurel, E. Mo_d, P. Perrin,C. Ristori,G. Ericsson,T. Johansson,O.
Tibell,M. Rey-Campagnolle, S.Polikanov,T. Krogulski,and J.Mougey (1992)Phys. Rev.
C45: 2332-2337.
Holzschdt=r, M., 1LE.Brown, LB. Camp, S. Comford, T. Darling, P. Dy=r, T. Goldman, S.
Hoibraten, K. Hosea, R.J. Hughes, N. Jarmie, R.A. Kenefiek, N.S.P. King, D.C. Liaon,
NLM. _¢to, M.M. Nfidzor, S.P. Parry, J. Rochet, R.A. Ristinen, M.1VL Schauer, J.A.
Scheckcr, and R.C. Wittebom (1993) Nuel. Phys. A558: 709c--718c.
Kanzleiter, R.J. "Thermodyn. amics of Nuclear Reactions Initiated by Antiproton Annihilations"
(1991) M.S. Thesis, Penn State University.
Lewis, R.A. et al. (1991) Nucl. Sci. & Eng. 109:411-415
Solcm, J. (1994) IBIS 47: 229-238.
VanDevender, P., and D.U Cook (1986) Science _'232: 831-g36.
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Antiproton catalyzed microfission/fusion propulsion

Antiproton catalyzed microfission/fusion propulsion

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