Thermonuclear Microexplosions Research Articles

The Ignition of Cylindrical Fusion Targets by Multi-Mega-Ampere GeV Proton Beams below the Alfvén Limit

Abstract It is shown that cylindrical deuterium targets can be ignited with multi-mega-ampere GeV proton beams below the Alfvén limit and a small amount of tritium. The proton beams can be generated by discharging a magnetically insulated gigavolt capacitor. Surrounding the thermonuclear microexplosion with a thick layer of liquid hydrogen, heated to a ~ 105 K plasma by the thermalization of the fusion reaction neutrons, most of the energy released can be converted into electric energy by a magnetohydrodynamic generator.

To Mars in Weeks by Thermonuclear Microbomb Propulsion

To reduce the radiation hazard for manned missions to Mars and beyond, a high-specific-impulse–high-thrust system is needed, with a nuclear bomb propulsion system the preferred candidate. The propulsion with small fission bombs is excluded because the critical mass requirement leads to extravagant small fission burnup rates. This leaves open the propulsion with nonfission ignited thermonuclear microexplosions, with a compact fusion microexplosion igniter (driver) and no large radiator. It should not depend on the rare isotope and only requires a small amount of tritium. This excludes lasers for ignition. With megaamperes of gigavolt proton beams and a small amount of tritium, cylindrical deuterium targets can be ignited. The proton beams are generated by discharging the entire spacecraft as a magnetically insulated gigavolt capacitor. To avoid a large radiator, needed to remove the heat from the absorption of the fast neutrons in the spacecraft, the microexplosion is surrounded by a thick layer of liquid hydrogen, stopping the neutrons and heating the hydrogen to a temperature of , which as a fully ionized plasma can be repelled from the spacecraft by a magnetic mirror.

Deuterium–tritium pulse propulsion with hydrogen as propellant and the entire space-craft as a gigavolt capacitor for ignition

A deuterium–tritium (DT) nuclear pulse propulsion concept for fast interplanetary transport is proposed utilizing almost all the energy for thrust and without the need for a large radiator:1.By letting the thermonuclear micro-explosion take place in the center of a liquid hydrogen sphere with the radius of the sphere large enough to slow down and absorb the neutrons of the DT fusion reaction, heating the hydrogen to a fully ionized plasma at a temperature of ∼105K.2.By using the entire spacecraft as a magnetically insulated gigavolt capacitor, igniting the DT micro-explosion with an intense GeV ion beam discharging the gigavolt capacitor, possible if the space craft has the topology of a torus.

Laboratory and Computer Simulation of the Processes of Electrodynamical Transfer of Plasma Energy And Momentum in the Schemes of Space Propulsions with Magnetic Field

Considered electrodynamics and the efficiency of the transfer of energy and momentum from the expanding clouds of diamagnetic or laser fusion plasma to the system of coils, creating a strong, axisymmetric quasi-dipolar magnetic field. The results of experiments with a laser-produced plasma and 3D/PIC-calculations are described, in which was proved for the first time a real opportunity to implement the conversion efficiency of energy and momentum at the level of up to 3÷5 % and ≥ 50 %, respectively, in a scheme developed for the interplanetary spacecraft VISTA on the basis of thermonuclear plasma microexplosions

Comparison of the recently proposed super-Marx generator approach to thermonuclear ignition with the deuterium-tritium laser fusion-fission hybrid concept by the Lawrence Livermore National Laboratory

The recently proposed super-Marx generator pure deuterium microdetonation ignition concept is compared to the Lawrence Livermore National Ignition Facility (NIF) Laser deuterium-tritium fusion-fission hybrid concept (LIFE). In a super-Marx generator, a large number of ordinary Marx generators charge up a much larger second stage ultrahigh voltage Marx generator from which for the ignition of a pure deuterium microexplosion an intense GeV ion beam can be extracted. Typical examples of the LIFE concept are a fusion gain of 30 and a fission gain of 10, making up a total gain of 300, with about ten times more energy released into fission as compared to fusion. This means the substantial release of fission products, as in fissionless pure fission reactors. In the super-Marx approach for the ignition of pure deuterium microdetonation, a gain of the same magnitude can, in theory, be reached. If feasible, the super-Marx generator deuterium ignition approach would make lasers obsolete as a means for the ignition of thermonuclear microexplosions.

Lasers for inertial confinement fusion driven by high explosives

Proposed laser fusion power plant concepts suffer from the huge size and expense of the lasers needed for compression and ignition. In a 1969 study (classified in 1970 and declassified in 2007), the idea to use chemical high explosives for the pumping of megajoule lasers was explored. Apart from being less expensive by orders of magnitude, such lasers are expected to be much more compact, and with their large energy, output could simultaneously drive several thermonuclear micro-explosion chambers. Because of its topical importance, I accepted the journal's invitation to publish a previously classified work, but with new unpublished ideas, with the previously classified paper put into the appendix.

Thinking in Different Ways to Combine Fusion with Fission

The common goal of CTR, but in particular of ICF, is low yield-high gain. Fission triggered large TN explosive devices meet the second but not the first of these conditions. These devices depend on the rare isotopes U235, Pu239, or U233, but for them the fusion energy output greatly exceeds the output from fission, limiting the fallout. In thinking about different ways to combine fusion with fission, there are three questions: (1) Are there ways where both conditions can be met, and where the fallout from fission is small? (2) Can the conditions be met without the use of U235, Pu239, or U233, but with U238, Th232, and perhaps with the fission of light nuclei like B10 or Li6, the latter having no fallout? (3) Are there concepts for MF, combining fusion with fission, without U235, Pu239 or U233? In my talk I will present reasons why under the above stated conditions two things seem to be possible: (1) The greatly facilitated fast ignition of thermonuclear microexplosions with a small amount of U238 or Th232. (2) The greatly enhanced pulsed MF burn aided by the fission of light nuclei such as B10, but also of the U238 and Th232 and with a neutron moderator. In either one of these cases the burn is “autocatalytic” in the sense that neutron-induced nuclear reactions in a halo surrounding the fusion plasma drive thermomagnetic currents compressing and increasing its neutron production rate.

Fast Fission Assisted Ignition of Thermonuclear Microexplosions

It is shown that the requirements for fast ignition of thermonuclear microexplosions can be substantially relaxed if the deuterium-tritium (DT) hot spot is placed inside a shell of U-238 (Th-232). An intense laser - or particle beam-projected into the shell leads to a large temperature gradient between the hot DT and the cold U-238 (Th-232), driving thermomagnetic currents by the Nernst effect, with magnetic fields large enough to entrap within the hot spot the α-particles of the DT fusion reaction. The fast fission reactions in the U-238 (Th-232) shell implode about 1/2 of the shell onto the DT, increasing its density and reaction rate. With the magnetic field generated by the Nernst effect, there is no need to connect the target to a large current carrying transmission line, as it is required for magnetized target fusion, solving the so-called “stand off” problem for thermonuclear microexplosions. - PACS number: 28.52.-s.

On the ignition of high gain thermonuclear microexplosions with electric pulse power

It was recently shown that the ignition of thermonuclear microexplosions seems possible with two Marx generators of modest size, one with a high current lower voltage for compression and confinement, and one with a high voltage lower current for ignition, transmitting their energy to the thermonuclear target by two nested magnetically insulated transmission lines. Here it is shown in much greater detail how this concept has the potential for the ignition of high gain thermonuclear microexplosions with a yield sufficiently low for a thermonuclear reactor and rocket propulsion. The concept also offers the possibility for the concurrent burn of deuterium–tritium with natural uranium or thorium.

Gigavolt pulsed power by magnetic levitation

A magnetically levitated and insulated torus of meter-size dimensions can be charged up to gigavolt potentials. Discharging the torus through a breach made by a plasma jet or spark gap, an intense relativistic ion beam can be extracted from a magnetically insulated diode. Because of its self-magnetic field, the beam can be transported over large distances, a property well suited for thermonuclear microexplosion ignition.

Boosting the specific impulse of high explosives by thermonuclear microexplosions ignited with the high explosives

The energy of a few 10 6 J, required to ignite a DT thermonuclear microexplosion, is really not very large. The problem is that it must be delivered to a target with a cross section less than 1 cm 2 in less than 10 nanoseconds, which can be done with lasers or particle beams in one step. By contrast, thermonuclear microexplosion ignition by a high explosive is achieved in two steps: First, the chemical energy ignites a magnetized fusion target with the energy released from this booster target igniting a second stage high gain high yield fusion or fission–fusion target. If ignited, a DT thermonuclear microexplosion can release an energy in excess of 10 9 J, or more than ∼1 ton of a chemical high explosive, but 80% of this energy goes into energetic neutrons. Therefore, to make full use of the fusion energy released into neutrons, the burnt explosive must form a layer surrounding the microexplosion, thick enough to absorb the neutrons, adding the nuclear energy released to the chemical energy of the high explosive. If, for example, about 100 times more energy is released in the microexplosion compared with the chemical energy stored in the high explosive, the specific impulse of the combined chemical-nuclear explosion would be increased 10 fold.

Thermonuclear microexplosion ignition by imploding a disk of relativistic electrons

A new ignition concept for thermonuclear reactions is described, in which an electron cloud produced by inductive charge injection and reaching the Brillouin limit, is magnetically compressed inside a long cylindrical solenoid. For sufficiently fast compression, the front of the cloud becomes a relativistically contracted annular disk of high-energy density, which upon impact on a grounded target leads to a cylindrical implosion easily exceeding the power fluxes required for the ignition of thermonuclear microexplosions. Unlike concepts proposed in the past to ignite thermonuclear microexplosions by relativistic electron beams, the energy delivered to the target is not in the form of kinetic particle energy but in the form of an intense electromagnetic pulse.

Circular magnetic macroparticle accelerator for impact fusion

The author proposes the use of a circular accelerator for gram-size superconducting macroparticles, with the acceleration to the velocities needed for impact fusion performed by a magnetic travelling wave. It is suggested to use the recently discovered high-Tc superconductors both for the macroparticle and for the establishment of the waveguide field. To give the macroparticle a large magnetic moment, it is proposed that it be composed of a densely packed lattice of superconducting grains embedded in a suitable insulator. Since the macroparticle can be kept in a stable orbit by a Braunbeck levitation configuration, the guide field can be static. The macroparticle can then be slowly accelerated along its circular track by a travelling magnetic wave, the field strength of which can be much weaker than the strength of the guide field so that the travelling wave can be generated by ordinary magnetic field coils. In a typical example, the accelerator would have a circumference of about 10 km and, to reach a velocity of about 200 km·s−1 as needed for impact fusion, the projectile would have to make about ten runs with an acceleration length of ∼ 100 km. For a gram-size projectile the kinetic energy would be large enough to ignite a thermonuclear microexplosion.

Thermophysics of the focusing mirrors for laser thermonuclear reactors

In this paper we examined several problems involved in the development of focusing systems of laser thermonuclear reactors. We analyzed the heating of mirrors by single and periodically repeating pulses of laser, x-ray, and neutron radiation. We estimated the permissible light loads on the mirror. The relations presented can be used to analyze the thermal state of the focusing mirrors of these reactors. We discussed methods for shielding the output optics from the products of the thermonuclear microexplosion. The greatest difficulties in preparing focusing mirrors and ensuring a long operational lifetime arise with the use of short-wavelength lasers and thermonuclear targets with large energy gain.

Inertial confinement fusion using only deuterium

A low input energy high gain inertial confinement fusion concept, depending only on deuterium as source material, is proposed. The concept makes use of a DT triggered thermonuclear deflagration in deuterium, whereby the tritium needed to make the trigger is obtained by separating the tritium burn product from the debris of the DD thermonuclear microexplosion. The separation of tritium from the remaining deuterium can conceivably be done with high efficiency by laser isotope separation.

Laser fusion experiments, facilities, and diagnostics at Lawrence Livermore National Laboratory

The progress of the LLNL Laser Fusion Program in our work to achieve high gain thermonuclear microex-plosions is discussed. Many experiments have been successfully performed and diagnosed using the large complex twenty-beam 30-TW Shiva laser system. A 400-kJ design of the twenty-beam Nova laser has been completed. The construction of the first phase of this facility has begun. The first phase of this Nd-doped low nonlinear index glass laser will consist of ten beams producing 100 kJ in 1-nsec pulses. One beam of the Argus laser has been converted to operation at 532 nm with 10-cm aperture. It will soon operate at 355 nm, also at 10-cm aperture. Frequency conversion crystals are being procured for full aperture operation at either 532 or 355 nm for both Argus beams. We also discuss new diagnostic instruments which provide us with new and improved resolution, information on laser absorption and scattering, thermal energy flow, supra-thermal electrons and their effects, and final fuel conditions. We have made measurements on the absorption and Brillouin scattering for target irradiations at both 1.064 microm and 532 nm. These measurements confirm the expected increased absorption and reduced scattering at the shorter wavelength. Additional data have been obtained on the angular distribution of suprathermal x rays, which further confirms our observation of its nonisotropy. However, we do not yet have an explanation of the phenomena. Implosion experiments have been performed which have produced final fuel densities over the 10-100x range liquid deuterium-tritium (DT) density. The 100x achievement is the highest yet achieved in laser fusion DT fuel targets.

Super-ion-beam accelerator for the ignition of thermonuclear reactions

A pulsed, multi-stage, high-voltage accelerator is proposed which should be capable of producing intense ion beams of many million amperes and many million volts. Super ion beams produced by this type of accelerator can exceed the limiting Aifvén current for light ions, typically 107 A, at which beam pinching occurs. The beam pinching of these super-beams permits them to be precisely focused onto a thermonuclear target. With such an accelerator it seems to be possible to reach a beam voltage of 108 V with a beam current of 107 A. The resulting beam power of 1015 W should be more than sufficient to ignite a DT thermonuclear microexplosion. By the formation of a stable ion beam superpinch within a thermonuclear target, such a large beam power in conjunction with the strong self-magnetic field of the beam may even lead to the ignition of the DD and perhaps HB11 thermonuclear reactions.

Black-body radiation as an inertial confinement fusion driver

To ignite a thermonuclear microexplosion a power source of ≳ 1014W is required with an energy of ≳106J focused down to ≲0.1 cm. To meet these driver requirements, charged particle beams1 and even hypervelocity projectiles2 have been proposed as an alternative to lasers for which an energy ≳106J is considered very large. Although charged particle beams and hypervelocity projectiles promise much larger energies the problem of the large driver power of ≳1014W remains. We propose here a two-stage driver concept which eliminates this problem. In it the initial energy is drawn from any of these drivers but is used here to generate an intense black-body radiation source. This black-body radiation is then used to drive the thermonuclear microexplosion target. This concept not only permits the initial driver power to be reduced by about two orders of magnitude from ≳1014W down to a few 1012W, but also greatly relaxes the beam-focusing requirements as compared with direct pellet fusion.

Generation of ultra-itense heavy ion beams for inertial confinement fusion

A pulse-power-driven, heavy-ion beam, ignition and inertial confinement system for thermonuclear microexplosions is proposed. The proposed method depends on already developed and tested techniques and has the potential of a high repetition rate, one of the requirements for a thermonuclear microexplosion reactor. In the proposed method, a space charge neutralized ion beam of modest intensity is projected into a long drift tube where it is radially confined by an applied axial magnetic field and axially compressed by a programmed variation of the diode voltage with time. Because the beam consists of a space charge neutralized flow of heavy ions, it behaves like a high atomic number plasma and, as such, rapidly looses internal energy by radiation during its axial compression. The axial compression proceeds isothermally until the beam becomes optically opaque where it reaches its maximum density. The axial beam compression greatly amplifies the final beam power over its initial value at the beam producing diode. In typical cases the initial beam power is ≃ 1010W, and in a drift tube ≃ 100 meters long can be amplified ≃ 104fold up to ≃ 1014W; but much larger beam powers are also possible. The accelerating voltage is typically in the range of several 106V and the diode current several 103A. Because the collision mean free path in the beam is smaller than the beam length, some unavoidable deviation from the programmed diode voltage will not lead to a dispersion of the beam. For typical cases the beam has, at its maximum compression, an atomic number density of ≃ 1018cm−3and a radius of ≃ 1 cm. After being compressed to its final maximum density the beam can, from there on, be easily focused on to the thermonuclear target. The use of singly ionized heavy ions in combination with an accelerating voltage of several 106V has the further advantage that the ion velocities are of the order of several 108cm sec−1, ideally matching the required optimal implosion velocity for the microexplosion target and thus implying a high beam energy conversion efficiency for ignition and confinement. For a final beam power of ≃ 1014W the diode cross-section is ≃ 102cm2. With a diode cross-section ≃ 103times larger, that is ≃ 10 m2, final beam powers up to ≃ 1017W will be possible, opening the prospect for igniting the DD and perhaps the HB11thermonuclear reactions.

Magnetically insulated linac driven by a multistage Marx generator

It is shown that a magnetically insulated linear accelerator driven by a multistage Marx generator can accelerate over short distances intense beams of heavy ions to multi-GeV energies. The attainable beam energies are sufficient for the ignition of thermonuclear microexplosions. The proposed accelerator could also ideally serve as a research tool for heavy ion induced nuclear reactions.