arXiv:0901.2993v1 [physics.soc-ph] 20 Jan 2009 The physical principles of thermonuclear explosives, inertial confinement fusion, and the quest for fourth generation nuclear weapons Andre Gsponer and Jean-Pierre Hurni Independent Scientific Research Institute Box 30, CH-1211 Geneva-12, Switzerland January 20, 2009 This document is the electronic version of the third printing (October 2002) of the seventh corrected and expanded edition of a report first distributed at the 1997 INESAP Conference, Shanghai, China, September 8–10, 1997. The second edition of this report was translated in Russian in 1998 by the Russian Foreign ministry in Moscow. Some minor modifications were made in order to achieve a proper linking of the figures, which could not be modified so that a double numbering scheme had to be used. A few papers, Refs. [591] to [596], which appeared after 2002 are appended to the bibliography as additional references. To Theodore B. Taylor and Marek Thee This report is an assessment of the prospect of developing new (i.e., fourth generation) nuclear weapons in the context of the Comprehensive Nuclear Test-Ban Treaty (CTBT) that was adopted by the UN General Assembly in 1996 and of the current moratorium on nuclear testing in effect in all nuclear-weapon States. The first chapter is a primer on thermonuclear weapons based on a scientific understanding of the physical principles of existing nuclear weapons and on the results of ISRINEX, a simple thermonuclear explosion simulation program specially developed for independent disarmament experts. Using this insight, it is shown that the construction of hydrogen bombs is in fact much less difficult than is generally assumed. Using present-day nuclear and computer technology, almost any modern industrial country could, in principle, build such a weapon. Similarly, it is shown that "boosting," i.e., the technique of using a small amount of tritium to enhance the performance of a fission bomb, is also much easier than generally assumed. In particular, using this technique, building highly efficient and reliable atomic weapons using reactor-grade plutonium is straightforward. Moreover, independently of the type of fissile material used, the construction of "simple" and "deliverable" tritium-boosted nuclear weapons can be easier than the construction of primitive Hiroshima or Nagasaki type atomic bombs. In May 1998, both India and Pakistan showed that they had successfully developed boosted fission weapons. Moreover, India claimed to have tested an advanced hydrogen bomb concept, and it is believed that two of their other four devices have used plutonium that was not classified as weapons grade. The second chapter is a technical and legal analysis of the nuclear tests which are allowed by the CTBT: microexplosions and subcritical experiments. It is found that this treaty explicitly forbids only nuclear explosions in which a divergent fission chain reaction takes place. Therefore, it is possible to develop new types of fission explosives in which subcritical fission-burn is the yield generation mechanism. Similarly, new kinds of fusion explosives, in which the trigger is no longer a fission explosive, are legal under the CTBT. The third chapter is devoted to the military applications of inertial confinement fusion (ICF) and other pulsed-power technologies. The capabilities of modern laboratory simulation techniques for weapons physics research are shown to significantly overlap with those of underground nuclear testing. Moreover, these technologies are found to enable the study of a number of physical processes — especially electromagnetic energy cumulation techniques and advanced nuclear processes that are not restricted by existing arms control treaties — which are useful in refining existing nuclear weapons and essential in developing fourth generation nuclear weapons. The fourth chapter is devoted to fourth generation nuclear weapons. These new fission or fusion explosives could have yields in the range of 1 to 100 ton equivalents of TNT, i.e., in the gap which today separates conventional weapons from nuclear weapons. These relatively low-yield nuclear explosives would not qualify as weapons of mass destruction. Seven physical processes which could be used to make such low-yield nuclear weapons, or to make compact non-fission triggers for large scale thermonuclear explosions, are investigated in detail: subcritical fission-burn, magnetic compression, superheavy elements, antimatter, nuclear isomers, metallic hydrogen and superlasers (i.e., ultrapowerful lasers with intensities higher than 10^19 W/cm^2). The conclusion stresses that considerable research is underway in all five nuclear-weapon States (as well as in several other major industrialized States such as Germany and Japan) on ICF and on many physical processes that provide the scientific basis necessary to develop fourth generation nuclear weapons. Substantial progress has been made in the past few years on all these processes, and the construction of large ICF microexplosion facilities in both nuclear-weapon and non-nuclear-weapon States is giving the arms race a fresh boost. The world runs the risk that certain countries will equip themselves directly with fourth generation nuclear weapons, bypassing the acquisition of previous generations of nuclear weapons. In this context, the invention of the superlaser, which enabled a factor of one million increase in the instantaneous power of tabletop lasers, is possibly the most significant advance in military technology of the past ten years. This increase is of the same magnitude as the factor of one million difference in energy density between chemical and nuclear energy. A major arms control problem of fourth generation nuclear weapons is that their development is very closely related to pure scientific research. The chief purpose of the CTBT is to freeze the technology of nuclear weapons as a first step toward general and complete nuclear disarmament. In order to achieve that, it is necessary to implement effective measures of preventive arms control, such as international legally binding restrictions in all relevant areas of research and development, whether they are claimed to be for military or civilian purposes. Contents: Executive summary v Acknowledgments xiii Introduction xv Units, conversion factors and metric prefixes xvii 1 The Physical Principles of Thermonuclear Explosives 1 1.1 Introduction 1 1.2 ISRINEX 2.6 physics 2 1.3 Fission explosives and boosting 7 1.4 Modern boosted fission explosives (Figs. 1.1–1.2) 11 1.5 The principle of the hydrogen bomb 18 1.6 The Teller-Ulam method (Fig. 1.3) 22 1.7 "Mike," the first hydrogen bomb (Figs. 1.4–1.7) 27 1.8 B-28: The first "miniature" multi-purpose H-bomb (Figs. 1.8–1.10) 32 1.9 1970-1980 thermonuclear designs (Fig. 1.11) 36 1.10 Thermonuclear detonation waves and spark ignition (Fig. 1.12) 39 2 Nuclear Weapons Development under the CTBT 59 2.1 The Comprehensive Test Ban Treaty 59 2.2 Subcritical tests and treaty limitations 60 2.3 Microexplosions and treaty limitations 62 2.4 Nuclear explosions and the "zero-yield" CTBT 65 2.5 Nuclear activities not prohibited by the CTBT and advanced nuclear processes 67 3 Nuclear Weapons Applications of Inertial Confinement Fusion 71 3.1 Introduction 71 3.2 Inertial Confinement Fusion (Fig. 3.1) 72 3.3 Total energy versus energy density (Fig. 3.2) 78 3.4 Equation of state (Fig. 3.3) 80 3.5 Opacity (Figs. 3.4–3.5) 81 3.6 Compressible turbulence (Figs. 3.6–3.7) 83 3.7 Radiation-driven hydrodynamics (Fig. 3.8) 84 3.8 Pure hydrodynamics (Fig. 3.9) 85 3.9 Radiative transport (Fig. 3.10) 85 3.10 ICF and nuclear weapons proliferation 85 4 Fourth Generation Nuclear Weapons 103 4.1 Introduction 103 4.2 Subcritical and microfission explosives (Figs. 4.1–4.2) 106 4.3 Transplutonic and superheavy elements 110 4.4 Antimatter 115 4.5 Nuclear isomers 125 4.6 Super-explosives and metallic hydrogen 130 4.7 Pure-fusion explosives 136 4.8 Superlasers (Figs. 4.3–4.4) 146 4.9 Technology of fourth generation nuclear weapons (Fig. 4.5) 152 5 Conclusion 163 6 Bibliography 171 6.1 Nuclear armament and disarmament 171 6.2 Fission weapons 176 6.3 Fusion weapons 177 6.4 Third and fourth generation nuclear weapons 180 6.5 Inertial confinement fusion 181 6.6 Subcritical fission and microfission 185 6.7 Shockwaves 186 6.8 Equations of state 187 6.9 Opacities 188 6.10 Instabilities 188 6.11 Superheavy elements 189 6.12 Antimatter 192 6.13 Nuclear isomers 198 6.14 Super-explosives and metallic hydrogen 201 6.15 Pure-fusion explosives 204 6.16 Cumulation of energy 208 6.17 High-energy-density and pulsed-power facilities 209 6.18 Superlasers 211 6.19 Technology 215 6.20 Additional references 216 List of Tables: 1 Metric prefixes xviii 1.1 Normalized maximum energy contents of nuclear fuels 45 1.2 Sequence of events and timing of a thermonuclear explosion 46 2.1 Major atomic and nuclear processes of importance to present and future military explosives 70 3.1 Major operating or planned particle-beam driven ICF facilities 91 3.2 Major operating or planned laser driven ICF facilities 92 4.1 Major operating or planned superlaser facilities 157 Acknowledgments: The work presented here would not have been possible without the financial and moral support of the Fondation Charles Léopold Mayer pour le progrès de l’Homme (FPH). In particular, we wish to thank Pierre Calame and Maurice Cosandey, as well as the other members of the Council and the executive staff of FPH, for their continuous support and encouragement. In the seven years during which the material on which this report is based was assembled and studied, we have benefited from conversations and correspondence with numerous people. We would like to thank in particular the following persons for their contribution — which in each case was significant to us: Masud Ahmad, Frank Barnaby, Thomas Cochran, Tom Zamora Collina, Freeman Dyson, Suren Erkman, Richard Garwin, Valery Govorukhin, Chuck Hansen, Frank von Hippel, P.K. Iyengar, Suzanne Jones, Martin Kalinowski, Ronald C. Kirkpatrick, Stefan Klement, J. George Linhart, Milo Nordyke, Christopher Pain, L. John Perkins, Vadim Simonenko, Carey Sublette, Ivan V. Sokolov, Naeem Tahir, Ted Taylor, Wang Xianpeng, William Westermeyer and Friedwardt Winterberg. Introduction: There are many good reasons for having independent expertise on nuclear weapons. The main reason, however, is simply that there are no scientific secrets on their physical principles: a State or organization wanting to make nuclear weapons can easily find the necessary basic information in the open literature. Access to modern computers of moderate capacity is therefore sufficient to design a nuclear weapon. Similarly, the same information is available to those who oppose nuclear weapons and wish to improve the quality of their arguments. On the other hand, the manufacture of a thermonuclear weapon, together with the special nuclear materials it is made of, has always been (and remains) a formidable engineering challenge, especially for technologically less advanced countries. For this reason, as long as independent expertise concentrates on scientific principles and not on engineering details, there is little risk it will contribute to horizontal proliferation. With this in mind, chapter one gives an introduction to the physics of thermonuclear weapons. We believe there is no compelling reason why such knowledge should remain the privilege of government experts working behind the curtain of secrecy. The main anti-proliferation impact of independent expertise on nuclear weapons is potentially on vertical proliferation. A good understanding of nuclear weapons physics is important to evaluate the future evolution of nuclear weapons technology, especially in the context of international agreements, such as the Comprehensive Nuclear Test-Ban Treaty (CTBT) and the Nuclear Non-Proliferation Treaty (NPT), which are supposed to put a halt to the development of new nuclear weapons. In particular, such an understanding is essential for the assessment of the links between modern simulation techniques and nuclear weapons, and for the analysis of fourth generation nuclear weapon concepts. These topics are the subject of chapters two, three and four. The concluding chapter of this report is followed by a bibliography containing more than 500 items. Finally, the question, "Why fourth generation nuclear weapons?" is not directly addressed in this report, as it involves broader political, social, and economic dimensions. The international system of units (MKSA) is used throughout. Practical units are used for plasma temperatures (electron-Volts instead of degrees Kelvin) and pressures (Megabars instead of Pascals). Explosive yields are expressed in kg or kt TNT equivalents. Conversion factors: 1 eV = 11604 °K 1 eV = 1.602 × 10^-19 J 1 bar = 10^5 Pa 1 Mbar = 100 GPa 1 kg TNT ≡ 10^6 cal = 4.184 MJ = 2.61 × 10^19 MeV 1 kt TNT ≡ 10^12 cal = 4.184 × 10^6 MJ = 2.61 × 10^25 MeV SI Prefixes: milli (m, 10^-3), micro (µ, 10^-6), nano (n, 10^-9), pico (p, 10^-12), femto (f, 10^-15), atto (a, 10^-18), zepto (z, 10^-21), yocto (y, 10^-24). kilo (k, 10^3), mega (M, 10^6), giga (G, 10^9), tera (T, 10^12), peta (P, 10^15), exa (E, 10^18), zetta (Z, 10^21), yotta (Y, 10^24). 1.1 Introduction: Introduces the physics of thermonuclear weapons: hydrogen bombs and boosted fission weapons, utilizing results from the simulation code ISRINEX 2.6. 1.2 ISRINEX 2.6 physics: ISRINEX models the ignition and burn of uniform thermonuclear plasmas under ideal inertial confinement. It includes three reaction classes: - Thermonuclear fusion reactions: T + D -> n + 4He + (17.6 MeV) (1.1) 3He + D -> T + 4He + (18.3 MeV) (1.2) D + D -> p + T + (4.0 MeV) (1.3) D + D -> n + 3He + (3.3 MeV) (1.4) - Neutron reactions: n + i -> n' + i' (1.5) n + 6Li -> T + 4He + (4.8 MeV) (1.6) n + 238U -> 237U + n + n' (1.7) n + 238U -> X + Y + n + n' + (180 MeV) (1.8) - Jetter cycle (1.9): Coupling of T+D and n+6Li. - Electromagnetic reactions: Bremsstrahlung, Compton, and inverse-Compton processes. Energy density: E = (3/2)Ni*k*Ti + (3/2)Ne*k*Te + (4*sigma/c)*Tr^4 (1.13). Thermonuclear equilibrium: Ti ≈ Te ≈ Tr = (c/(4*sigma)*E)^(1/4) (1.14). 1.3 Fission explosives and boosting: Boosted fission bombs ignite a small DT gas mixture to produce high-energy 14 MeV neutrons, substantially multiplying fission efficiency late in the chain reaction without requiring heavy tampers or reflectors. Low temperature limit: kT = (2/3)*(eta/Zeff)*Ef (1.15). High temperature limit: kT ≈ 18[keV] * (eta*chi)^(1/4) (1.16). Critical temperatures for ignition with external X-ray heating are 2.4 keV for DT, 9 keV for D-3He, and 10 keV for DD. DT is thus the only fuel viable for boosting. 1.4 Modern boosted fission explosives: Details a hollow-pit design with ~4 kg fissile material, 2.2 g DT gas (1.3 g tritium), and ~10 kg HE. Probability of fission per DT neutron: Pf ≈ (sigma_f/sigma_t)*(1 - exp(-n*sigma_t*R)) (1.17). Boosted efficiency Pf ≈ mu * (Nn/Nf) = mu * (m/M)*(A/a) (1.18). Demonstrates that even a fission fizzle (~0.1 kt) yields ~1 kt with boosting and ~10 kt with supercritical multiplication (mu ≈ 5). 1.5 The principle of the hydrogen bomb: Explores the physics of multi-megaton fusion burn, disassembly time scales (tau_d ≈ (R/c_s)*sqrt(M/m) (1.19)), burn times (tau_b ≈ 1/(2*Ni*<sigma_DD*v>) (1.20)), and the requirement of 100-500x solid density compression for D2 or LiD fuels. 1.6 The Teller-Ulam method: Uses soft X-rays produced by a primary to compress and ignite a physically separate secondary via radiation-driven ablation in a hohlraum. Ablation pressure: p_abl ≈ Zeff*Np*k*Th (1.22). Compares Teller mode (fissile sparkplug-assisted ignition) and Wheeler mode (equilibrium volume self-ignition). 1.7 "Mike," the first hydrogen bomb: Detailed reverse-engineering and simulation of the 10.4 Mt Mike shot (2.4 Mt fusion, 8.0 Mt fission from 238U tamper). Liquid deuterium (850 L, ~120 kg), 5000 kg U-238 pusher/tamper, and an 18 kg Pu-239 central sparkplug. 1.8 B-28: The first miniature multi-purpose H-bomb: Analysis of the stockpiled US B-28 bomb (~1.2 Mt yield, ~820-1000 kg weight) utilizing solid 6LiD fuel, a 400 kg U-238 tamper, and a 12 kg U-235 sparkplug. 1.9 1970-1980 thermonuclear designs: Evolution toward miniaturization, high yield-to-weight ratios (1-2 kt/kg), sparkplug-less Wheeler-mode designs, and enriched uranium (HEU) secondaries (e.g., W78 and W87 warheads). 1.10 Thermonuclear detonation waves and spark ignition: Analyzes propagation of supersonic thermonuclear burn waves: wave thickness lambda = tau_b * c_s * M_s (1.26), ratio Omega = (R/lambda)*chi_s (1.27). Discusses modern spherical secondary configurations (W80, W88) and aspherical primary pits for inherent safety. Table 1.1: Normalized maximum energy contents of nuclear fuels - H-Hbar (Antimatter): M=2, Density=0.08 kg/L, Yield-to-weight=21,400 kt/kg, Yield-to-volume=1,700 kt/L - DD: M=4, Density=0.17 kg/L, Yield-to-weight=80 kt/kg, Yield-to-volume=13 kt/L - DT: M=5, Density=0.22 kg/L, Yield-to-weight=80 kt/kg, Yield-to-volume=18 kt/L - 6LiD: M=8, Density=0.80 kg/L, Yield-to-weight=50 kt/kg, Yield-to-volume=40 kt/L - Pu/235U: M=239/235, Density=19 kg/L, Yield-to-weight=17 kt/kg, Yield-to-volume=320 kt/L Table 1.2: Sequence of events and timing of a thermonuclear explosion [nanoseconds] Primary: - Compression by chemical high explosives (HE): 10,000 - 50,000 ns - Rayleigh-Taylor instability (HE/Pu boundary): 5,000 - 10,000 ns - Rayleigh-Taylor instability (Pu/DT boundary): 100 - 400 ns - Chain reaction: 150 - 300 ns - Rayleigh-Taylor instability (Pu/DT mixing): 2 - 8 ns - Boosting (DT burn): 1 - 4 ns - X-ray pulse: 10 - 50 ns - Fission core disassembly: 10 - 50 ns - Full disassembly: 500 - 2,000 ns Primary/Secondary: - X-ray arrival time: 1 ns - Neutron arrival time: 20 ns - Shock wave arrival time: 1,000 ns - X-ray thermalization within hohlraum: 10 ns Secondary: - Ablative compression: 100 - 500 ns - Chain reaction (sparkplug): 10 - 30 ns - Thermonuclear burn: 3 - 20 ns - Fusion fuel disassembly: 3 - 20 ns Figures Included in Chapter 1: - Fig. 1.1: Schematic diagram of a boosted fission pit (uncompressed vs compressed). - Fig. 1.2: Time evolution of DT burn efficiency and plasma ion temperature for Tb = 1.5, 2.0, 2.5 keV. - Fig. 1.3: The Teller-Ulam-Sakharov-Zel'dovich radiation implosion principle. - Fig. 1.4: Main components of the "Mike" 10.4 Mt thermonuclear device. - Fig. 1.5: Dimensions and compression factors of the "Mike" secondary at maximum compression. - Fig. 1.6: Simulation of "Mike" in Wheeler mode for compression factors chi = 100 to 500. - Fig. 1.7: Simulation of "Mike" in Teller mode (with 6 keV sparkplug). - Fig. 1.8: Plausible schematic and mass/yield breakdown of the B-28 bomb (1.2 Mt). - Fig. 1.9: Simulation of B-28 LiD burn in Wheeler mode. - Fig. 1.10: Simulation of B-28 LiD burn in Teller mode. - Fig. 1.11: Schematic diagram of the W78/Mk-12A RV (330 kt yield, ~200 kg warhead weight). - Fig. 1.12: Modern low-weight spherical secondary RV design (150-300 kt yield, <200 kg total weight). 2.1 The Comprehensive Test Ban Treaty: Explains that while the CTBT bans nuclear test explosions, non-explosive laboratory methods and advanced simulations (such as Science Based Stockpile Stewardship - SBSS) allow continued weapons physics refinement. 2.2 Subcritical tests and treaty limitations: During negotiations, the P-5 agreed that subcritical experiments (where no self-sustaining divergent chain reaction occurs) are not prohibited by the CTBT. This legal interpretation allows experiments with fissile materials under dynamic high pressures, provided criticality is not reached. 2.3 Microexplosions and treaty limitations: Contained millimeter-sized microexplosions driven by lasers or particle beams (ICF) were excluded from NPT and CTBT bans under understandings dating back to 1975 and reaffirmed in 1996. Yields ranging from 0.1 to 10 tons TNT equivalent are legally permissible in laboratory containment. 2.4 Nuclear explosions and the "zero-yield" CTBT: The technical distinction between a zero-yield policy for full-scale fission-chain weapons and allowable microexplosions/subcritical burns creates a loophole for low-yield non-conventional nuclear explosives (1 to 100 tons TNT). 2.5 Nuclear activities not prohibited by the CTBT and advanced nuclear processes: Details processes permissible under the CTBT that can enable fourth-generation nuclear weapons: - Standard processes: chemical detonation, lasers, fission, fusion, particle accelerators. - Advanced processes: magnetic compression, atomic isomerism, x-ray lasers, superlasers, subcritical fission, nuclear isomerism, gamma-ray lasers, muon catalysis, antimatter. - Exotic processes: metallic hydrogen, atomic clusters, superheavy nuclei, bubble nuclei, halo nuclei. 3.1 Introduction & 3.2 Inertial Confinement Fusion: ICF targets (containing 1 µg to 5 mg of DT) simulate thermonuclear secondary physics under laboratory conditions. Indirect-drive hohlraums mimic Teller-Ulam radiation implosion. 3.3 Total energy versus energy density: While ICF yield is low (kg TNT equivalent vs kt/Mt in weapons tests), the specific energy density achieved (up to 20 kt/kg) overlaps directly with nuclear weapons test conditions. 3.4 Equation of State (EOS): ICF facilities probe high-pressure/high-temperature EOS in the 10 Mbar to 5 Gbar regime, closing gaps between low-pressure laboratory data and statistical Thomas-Fermi-Dirac models. 3.5 Opacity: Laser-heated hohlraums achieve radiatively driven local thermodynamic equilibrium (LTE), measuring M-shell-dominated X-ray opacities of heavy elements (including uranium, Z=92). 3.6 Compressible turbulence: Investigates Rayleigh-Taylor, Kelvin-Helmholtz, and Richtmyer-Meshkov instabilities to quantify turbulent mixing at material interfaces during implosion. 3.7 Radiation-driven hydrodynamics, 3.8 Pure hydrodynamics, and 3.9 Radiative transport: Demonstrates that NIF and LMJ recreate the radiation-dominated conditions (radiation temperature 0.2–1 keV, multimegabar/gigabar dynamic pressures, diffusive transport) found in nuclear weapons secondaries. 3.10 ICF and nuclear weapons proliferation: Highlights horizontal and vertical proliferation risks: ICF research enables non-nuclear-weapon states to master the physics of thermonuclear secondaries and develop compact fourth-generation designs. Table 3.1: Major operating or planned particle-beam driven ICF facilities - Saturn (USA, SNL, 400 kJ / 5 ns, 36 beams) - PBFA-II-Z (USA, SNL, 1500 kJ / 20 ns, 36 beams) - ILSE (USA, LBL, 6400 kJ / 10 ns, 16 beams, Design stage) - KALIF (Germany, Karlsruhe, 40 kJ / 40 ns, 1 beam) - HIBALL (Germany, 5000 kJ / 20 ns, 20 beams, Design stage) - HIDIF (Europe, 3000 kJ / 6 ns, 48 beams, Design stage) Table 3.2: Major operating or planned laser driven ICF facilities (Glass, KrF, Iodine lasers): Lists major facilities across USA (Nova, NIF, Omega, Nike, Mercury), Japan (Gekko-XII, Kongoh, Koyo, Ashura, Super-Ashura), France (Phebus, Megajoule, LULI, Octal), China (Shen-Guang I-III, Tin-Guang), UK (Vulcan, Helen, Titania, Sprite), Russia (Delfin, Iskra-5), Germany (Asterix IV, PHELIX booster), India (Indore), Israel (ALADIN, Continuum), Italy (ABC), and Korea (Sinmyung-I). Figures Included in Chapter 3: - Fig. 3.1: Advanced indirect-drive ICF target (5 mg DT fuel, hohlraum driven by heavy ions, lasers, or antiprotons). - Fig. 3.2: Total energy vs. specific energy density parameter space (Weapons tests vs NIF, Nova, Saturn, Jupiter, Atlas, Pegasus, DARHT). - Fig. 3.3: Equation of state parameter space (Pressure vs Temperature: Hugoniot, Pulsed power, Nova, NIF, Weapons test). - Fig. 3.4: Opacity parameter space (Atomic number Z vs Temperature in eV). - Fig. 3.5: Opacity parameter space (Z vs Target lifetime / equilibration time). - Fig. 3.6: Compressible turbulence (Compression & Shock pressure vs Sample size / perturbation wavelength). - Fig. 3.7: Compressible turbulence (Mach number & Shock pressure vs Sample size / perturbation wavelength). - Fig. 3.8: Radiation-driven hydrodynamics (Rosseland MFP in uranium vs Radiant flux). - Fig. 3.9: Pure hydrodynamics (Ratio of matter temperatures Tu/TLid vs Dynamic pressure in Gbar). - Fig. 3.10: Radiative transport (E_rad/E_mat vs Mean free paths). 4.1 Introduction: Explores non-conventional nuclear explosives with yields in the 1 to 100 ton range that bridge the gap between conventional high explosives and strategic nuclear weapons, without generating significant residual radioactive fallout. 4.2 Subcritical and microfission explosives: Neutron multiplication: k = k_infinity - l (4.1); Rossi alpha: dn/dt = ((k-1)/tau_a)*n = alpha*n (4.3); Subcritical gain: n(infinity) = n(0)/(1 - k) (4.5). Utilizing ~10^18 external neutrons (produced via antiproton annihilation or superlaser-induced reactions) allows complete subcritical fission burn of milligram-sized plutonium pellets, yielding 0.24 to 12 tons TNT. 4.3 Transplutonic and superheavy elements: Critical mass: m_c = (4*pi/3)*(omega_c^3 / rho^2) (4.6); Critical opacity: omega_c = (A / (N*sigma_t))*(pi/k_0 - z_0) (4.7). For superheavy nucleus 298_114 (doubly magic island of stability), critical mass could be as low as ~20-260 grams, providing compact triggers for microfission/fusion. 4.4 Antimatter: Antiproton-proton annihilation releases 275 times more kinetic energy per mass than DT fusion. Less than 1 microgram of antihydrogen is sufficient to trigger subcritical fission or ignite a 1 kt "clean" pure-fusion bomb. Discusses antiproton storage in traps and condensed matter, and results from CERN (LEAR, AD). 4.5 Nuclear isomers: Metastable excited nuclear states (spin and shape isomers, e.g., 180Tam, 178Hfm2, 68Ni, superdeformed nuclei) store energy densities from kJ/g to GJ/g without intrinsic radioactivity. Triggering de-excitation via X-ray lasers or superlasers could yield table-top gamma-ray flashbulbs and compact explosives. 4.6 Super-explosives and metallic hydrogen: Theoretical metastable metallic hydrogen (predicted to form at >1.4-3 Mbar) could store ~270 kJ/cm^3 (~35-50x more than TNT), serving as an ultra-powerful propellant or compact chemical implosion driver. 4.7 Pure-fusion explosives: Reviews concepts for igniting DT/DD fuel without a fission primary: chemical explosive implosion (concentric/spherical cumulation), impact fusion (electromagnetic guns, hypervelocity flyers >25-200 km/s), plasma pinch/Z-pinch machines (PBFA-Z, MAGO, Shiva Star), and explosive flux compression generators. 4.8 Superlasers: Chirped-pulse amplification (CPA) enables tabletop laser intensities exceeding 10^19 to 10^21 W/cm^2. Superlasers can induce photo/electrofission, relativistic self-channeling, electron acceleration, positron/pair production, and fast ignition of ICF targets, reducing driver energy requirements by 10-100x. 4.9 Technology of fourth generation nuclear weapons: Synthesizes staging concepts, combining magnetic compression, MEMS/nanotechnology, microtraps, and ICF pellet targets with antimatter or superlaser triggers to construct sub-kilogram "atomic bullets" and miniature tactical munitions. Table 4.1: Major operating or planned superlaser facilities - USA: Petawatt (LLNL, 1000 J / 0.5-20 ps, 1000 TW, >10^21 W/cm^2), JanUSP (LLNL, 15 J / 0.085 ps, 200 TW, 2x10^21 W/cm^2), Trident (LANL), LABS II (LANL), UM Ann Arbor, WSU Pullman. - UK: Vulcan (RAL, 180 J / 1 ps, 200 TW, 10^20 W/cm^2; 1000 J / 1 ps, 1000 TW Design), Astra, Titania, Sprite. - Japan: Petawatt (ILE Osaka, 1000 J / 1 ps, 1000 TW Design), PW-M (ILE), Petawatt (APRC, 30 J / 0.03 ps, 1000 TW Design), RIKEN. - France: Petawatt (CESTA Bordeaux, 1000 J / 1 ps, 1000 TW Design), P-102 (CEL-V Limeil, 50 J / 0.5 ps, 80 TW, >10^19 W/cm^2), LOA Palaiseau, ELIA Bordeaux. - Germany: PHELIX (GSI Darmstadt, 1300 J / 0.42 ps, ~1000 TW Design), Ti-Nd (MBI Berlin), ATLAS (MPQ Garching), IOQ Jena. - Russia: Progress-P (St. Petersburg, 55 J / 1.5 ps, ~30 TW, 10^19 W/cm^2). - China: BM (~3 TW). Figures Included in Chapter 4: - Fig. 4.1: Dependence of initial neutrons/antiprotons required for 100% subcritical burn vs pellet density for 14, 70, and 700 mg plutonium pellets (yields: 240 kg, 1,200 kg, 12,000 kg TNT). - Fig. 4.2: Compression work (Joule and kg HE equivalent) vs final pellet density, showing the critical vs subcritical boundary. - Fig. 4.3: Tabletop laser focused intensity vs year (1960–2000), showing the 10^6 jump via chirped pulse amplification up to the relativistic regime. - Fig. 4.4: Electron quiver energy and accessible nuclear/relativistic phenomena as a function of Nd:glass laser intensity (X-ray sources, relativistic plasmas, nuclear fission/fusion, pair production, pion production). - Fig. 4.5: Two-step indirect-drive ICF target concept for compression and fast ignition utilizing advanced triggers (nuclear isomers, superlasers, antiprotons). Summarizes the findings and arms control implications: 1. The physical principles of high-yield thermonuclear explosives and tritium-boosted fission weapons are simple, robust, and well-understood. Modern computational capabilities and open physics allow technologically advanced countries (e.g., Germany, Japan, India, Pakistan, Israel) to design reliable weapons without full-scale nuclear testing. 2. Tritium-boosting eliminates preinitiation issues, enabling the reliable use of reactor-grade plutonium for nuclear weapons. 3. The exclusion of laboratory microexplosions and subcritical tests from CTBT prohibition creates a legal and technological gateway for developing fourth-generation low-yield nuclear explosives (1 to 100 tons TNT). 4. Advanced simulation facilities (NIF, LMJ, superlasers, pulsed power generators) replicate the high-energy-density physics of thermonuclear weapons, eroding traditional nonproliferation barriers. 5. To achieve genuine nuclear disarmament and prevent the emergence of fourth-generation weapons, arms control must be expanded to include preventive, legally binding restrictions on military-relevant fundamental research in high-energy-density physics, antimatter, nuclear isomers, and laser fusion. Comprehensive bibliographic catalog comprising 596 numbered references categorized under: - 6.1 Nuclear armament and disarmament (Refs. 1–57) - 6.2 Fission weapons (Refs. 58–71) - 6.3 Fusion weapons (Refs. 72–107) - 6.4 Third and fourth generation nuclear weapons (Refs. 108–123) - 6.5 Inertial confinement fusion (Refs. 124–171) - 6.6 Subcritical fission and microfission (Refs. 172–183) - 6.7 Shockwaves (Refs. 184–200) - 6.8 Equations of state (Refs. 201–213) - 6.9 Opacities (Refs. 214–217) - 6.10 Instabilities (Refs. 218–223) - 6.11 Superheavy elements (Refs. 224–261) - 6.12 Antimatter (Refs. 262–344) - 6.13 Nuclear isomers (Refs. 345–378) - 6.14 Super-explosives and metallic hydrogen (Refs. 379–421) - 6.15 Pure-fusion explosives (Refs. 422–474) - 6.16 Cumulation of energy (Refs. 475–499) - 6.17 High-energy-density and pulsed-power facilities (Refs. 500–523) - 6.18 Superlasers (Refs. 524–578) - 6.19 Technology (Refs. 579–590) - 6.20 Additional references (Refs. 591–596)