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A simple deuterium DC glow discharge was employed to study the production of densely packed deuterium clusters with high binding energies in palladium. The incident ions create damage cascades leading to the production of defects such as vacancies, dislocations, and voids. These defects trap interstitial deuterons with binding energies dependent on the trap’s geometry and volume. 1 Varying fluences of incident ions were used (1E18 ions/cm 2 , 1E19 ions/cm 2 , and 1E20 ions/cm 2 ) and incident energies dependent on cathode bias (-0.75 kV, -0.875 kV, and -1.0 kV). Thermal Desorption Spectroscopy (TDS) was used to estimate the clusters’ trapping energies. 2 There appeared to be a deuterium trapping limit dependent on defect concentration where once a distinct defect density was met any further damage was counterproductive in deuterium trapping. The condition that produced the most trapped deuterium was -0.75 kV in 1 Torr deuterium with a fluence of 1E18 ions/cm 2 . Some samples were observed under SEM and TEM. The results showed surface pit and blister formations which grew in concentration as the fluence increased. Beneath the surface formations, cross-section images showed large voids and holes in the material with cracks at grain boundaries. TEM images displayed the resulting damage structure which extended ~250 nm into the cathode for a sample at 1.0 Torr and -1.0 kV. A proposal is that as the damage concentration increased, these voids grew to such an extent that they formed the blisters and eventually ruptured.

The importance of the development of chirped pulse amplification (CPA) was highlighted with the award of the 2018 Nobel Prize in Physics to Gerard Mourou and Donna Strickland. CPA laser physics ope...

After achieving significant research results on laser-driven boron fusion, the essential facts are presented how the classical very low-energy gains of the initially known thermal ignition conditions for fusion of hydrogen (H) with the boron isotope 11 (HB11 fusion) were bridged by nine orders of magnitudes in agreement with experiments. This is possible under extreme non-thermal equilibrium conditions for ignition by >10 PW-ps laser pulses of extreme power and nonlinear conditions. This low-temperature clean and low-cost fusion energy generation is in crucial contrast to local thermal equilibrium conditions with the advantage to avoid the difficulties of the usual problems with extremely high temperatures.

For developing a laser boron fusion reactor driven by picosecond laser pulses of more than 30 petawatts power, advances are reported about computations for the plasma block generation by the dielectric explosion of the interaction. Further results are about the direct drive ignition mechanism by a single laser pulse without the problems of spherical irradiation. For the sufficiently large stopping lengths of the generated alpha particles in the plasma results from other projects can be used., 10 pages, 5 figures, extended tex from lectures on 5th and 6th June 2017in Shanghai/China

Pressures created by non-thermal forces from picosecond CPA laser pulses of extreme power can be higher than the hundred million °C temperatures for the usual ignition of fusion of clean and abundant laser boron fusion.

Nuclear reactions produce ten million times more energy than the chemical reactions e.g. from burning carbon, but the equilibrium thermal pressures for chemical reactions need temperatures of hundred °C while nuclear burns need many dozens of million °C. This is on the level for ITER or at NIF with using nanosecond laser pulses. In contrast, non-thermal pressures can be higher by lasers using nonlinear forces of picoseconds or shorter duration as computer results of 1978 had demonstrated by non-thermal plasma-block acceleration. This is in full agreement with the ultrahigh acceleration measured by Sauerbrey since 1996 thanks to his use of ultra-extreme powers of picosecond CPA-laser pulses. Even the very inefficient classical fusion of hydrogen with the 11B can be used for the non-thermal reaction with sufficiently modest heating in a reactor for generation electricity.

Exceptionally high reaction gains of hydrogen protons measured with the boron isotope 11 are compared with other fusion reactions. This is leading to the conclusion that secondary avalanche reactions are happening and confirming the results of high-gain, neutron-free, clean, safe, low-cost, and long-term available energy. The essential basis is the unusual non-thermal block-ignition scheme with picosecond laser pulses of extremely high powers above the petawatt range.

Changing the high intensity interaction time of lasers with plasma from nanosecond duration to picoseconds results in a categorically different regime. With high intensity picoseconds laser pulses, the optical energy is converted directly into kinetic energy of plasma blocks without thermal losses, without delays by collisions, and with exclusion of most of the instabilities. Following the long known theory by the nonlinear (ponderomotive) force, the plasma receives a predicted ultrahigh acceleration in agreement with measurements by Sauerbrey. Interaction of the generated plasma blocks with solid state fusion fuel should produce a side-on ignition of a Chu-Bobin fusion flame. Using hydrodynamics with separate electron and ion fluids, detailed properties can be studied about shock generation, including the varying velocity of the flame fronts far . Results from recent computations confirm how the collective nonthermal nonlinear force driven plasma interactions are causing only marginal electron heating.

A fundamental difference of very high intensity laser interaction with plasmas from solid targets appears with lasing at picosecond (ps) pulse durations in contrast to pulses of nanoseconds (ns). This can be seen from the more than 10,000 times higher acceleration with ps pulse durations than with thermal pressure determined interaction. A ps pulse duration produces instantly acting high-efficiency nonlinear (ponderomotive) electrodynamic force dominated acceleration in contrast to heating with longer pulses. The ps pulses accelerate high-density plasma blocks. This can be used by a new scheme of side-on driven laser fusion with generating a flame ignition in uncompressed fusion fuel of solid density resulting in a reaction velocity of more than 2000 km/s for DT.

The new candidates for laser fusion energy with minimized radioactivity were presented. The possibility of side-on laser ignition of H–11B with negligible radioactivity encouraged to study the fusion of solid state H–7Li fuel which again turns out to be only about ten times more difficult than the side-on ignition of solid deuterium–tritium using petawatt-picosecond laser pulses at anomalous interaction conditions if very high contrast ratio. Updated cross sections of the nuclear reaction are included. In other words, the specific approach discussed here involves inducing a fusion burn wave without radioactivity by laser-driven impact of a relatively large block of plasma on the outside of a solid density H–11B and H–7Li targets.

The hot spot heating process by an assumed deuteron beam is evaluated in order to estimate the contribution of the energy produced by the deuteron beam-target fusion to the heating process. The deuteron beam energy versus the number of deuterons is evaluated through the experimentally achieved proton beam energy distribution using the TRIDENT short pulse laser at the Los Alamos National Laboratory (LANL). The corresponding hot spot heating is then calculated using this assumed deuteron beam spectrum. The resulting first order heating dynamics is employed in the expanded “bonus” energy calculation, and a 12.73% extra energy from deuteron beam-target fusion was found with the assumed deuteron spectrum when ρrb = 4.5 g/cm2 is considered, where ρ is the fuel density, and rb is the ion beam focusing radius on the target. The results provide further insight into the contribution of the extra heat produced by deuteron beam-target fusion to the hot spot ignition process. A further analysis of how a converter foil using ultra-high-density cluster materials can help to achieve the yield requirements for ignition is presented.

An extreme anomaly of laser-plasma interaction with petawatt-picosecond (PW-ps) pulses of very high contrast ratio for suppression of relativistic self-focusing permitted a come-back of the Bobin-Chu side-on ignition of uncompressed deuterium-tritium (DT) fusion fuel. The plasma blocks for the side-on ignition have to be produced by the well confirmed nonlinear force acceleration which is about 100,000 times higher than thermo-kinetic fluid-dynamic acceleration for comparison with astrophysical cases. It is essential that the dielectric plasma properties within the nonlinear force are used. Using the measured ion beam densities above 1011 A s/cm2 the ignition mechanism needed numerical and theoretical studies of extremely strong shock phenomena. When extending these results to the side-on ignition of uncompressed hydrogen-boron11 (HB11), surprisingly, the ignition by this shock mechanism was only about 10 times more difficult than for DT in contrast to ignition by spherical laser driven compression using thermo-kinetic conditions in which case HB11 ignition is 100,000 times more difficult than DT.

An anomalously strong increase of nuclear fusion gains for laser driven compression and thermal ignition of hydrogen-boron11 has been discovered from computations by using the latest results of Newins and Swain about details of a resonance maximum of the astrophysical S-function at 148 keV for the reaction cross-sections. Extensive computations based on volume ignition showed some usual improvements of the fusion gains. However, for a very narrow range of parameters, the increase of the gain was found to be higher by more than a factor 6. This is very unusual in all similar computations and is related to retrograde properties which were known for other parameter values. On top it is most important that the anomalous range is in the practically very interesting range for incorporation of laser pulse energies of few megajoules. The gains of up to 20 may be of interest for power generation in future by the high density fusion scheme.

In contrast to the usual laser fusion scheme with spherical irradiation and very high compression and ignition of fuel, the alternative scheme with side-on ignition of uncompressed solid density of fuel (Chu) may lead to a solution by using the now available picosecond laser pulses with higher than petawatt power. A necessary condition is to use clean laser pulses with better than 108contrast ratio for suppression of relativistic self-focusing. When updating the analysis of Chu for fusion of deuterium-tritium and proton-11B, one problem is that the correct use of the stopping power of the alpha particles had to be solved. Discrepancies are evaluated in view of the stopping power at the low temperature range of the plasmas where the change of the emitted bremsstrahlung is involved.

Clusters of condensed deuterium of densities up to 1029cm−3in pores in solid oxide crystals were confirmed from time-of-flight mass spectrometry measurements. Based on these facts, a schematic outline and possible conclusions of expectable generalizations are presented, which may lead to a simplification of laser driven fusion energy including new techniques for preparation of targets for application in experiments of the NIF type, but also for modified fast igniter experiments using proton or electron beams or side-on ignition of low compressed solid fusion fuel.

Energy production by laser driven fusion energy is highly matured by spherical compression and ignition of deuterium-tritium (DT) fuel. An alternative scheme is the fast ignition where petawatt (PW)-picosecond (ps) laser pulses are used. A significant anomaly was measured and theoretically analyzed with very clean PW-ps laser pulses for avoiding relativistic self focusing. This permits a come-back of the side-on ignition scheme of uncompressed solid DT, which is in essential contrast to the spherical compression scheme. The conditions of side-on ignition thresholds needed exorbitantly high energy flux densities E*. These conditions are now in reach by using PW-ps laser pulses to verify side-on ignition for DT. Generalizing this to side-on igniting solid state density proton-Boron-11 (HB11) arrives at the surprising result that this is one order of magnitude more difficult than the DT fusion. This is in contrast to the well known impossibility of igniting HB11 by spherical laser compression and may offer fusion energy production with exclusion of neutron generation and nuclear radiation effects with a minimum of heat pollution in power stations and application for long mission space propulsion.

Controlled fusion energy from burning hydrogen with boron-11 is of interest because no neutrons are produced. Following the scheme of ignition by spherical irradiation by laser or particle beams, one has to deal with exorbitant conditions of densities and input energies. A new approach following the scheme of block ignition with laser pulses of picosecond (ps) duration and more than petawatt (PW) power led to the possibility of plane geometry irradiation of the fuel using the anomalous effect of block ignition for deuterium tritium (DT) based on updated conditions for the initial computations. We present the extension for H-11B resulting in a very less dramatic difference to DT than in the case of spherical pellet geometry. Ignition thresholds may be only about one order of magnitude higher and the needed temperatures of about 50 keV are no problem for the skin layer acceleration by nonlinear forces (SLANF) for the block generation.

A fuel cell using nontraditional fuel and oxidizer is investigated in this research. H 2 O 2 is used in this unique fuel cell directly at the cathode. Two types of reactant, namely, a gas-phase hydrogen and an aqueous NaBH 4 solution, were used as fuel at the anode. The direct utilization of H 2 O 2 and NaBH 4 at the electrodes, as seen in experiments, results in >30% higher voltage output compared to the ordinary H 2 /O 2 fuel cell. Further, the unique combination of NaBH 4 and H 2 O 2 , both of which are in an aqueous form, has numerous advantages from an operational point of view. This design is inherently compact compared to other cells that use gas-phase reactants. Consequently, the peroxide-based fuel cell is well suited for space power applications where air is not available and a high-energy density fuel is essential.

Fast ignition for fusion energy by using petawatt-picosecond (PW-ps) laser pulses was modified due to an anomaly based on extremely clean suppression of prepulses. The resulting plasma blocks with space charge neutral ion current densities above 1011Amp/cm2may be used to ignite deuterium-tritium at densities at or little above solid state density. The difficulty is to produce extremely high energy flux densities of the blocks. Results are reported how the threshold can be reduced by a factor up to fife if the inhibition factor for thermal conductivity due to electric double layers is included in the hydrodynamic analysis.

Ion density measurements have been performed on the plasma generated by an ablative diode laser thruster using a negatively biased flat plate probe. The biased probe data was coupled with measurement of the ablation crater through use of a scanning electron microscope (SEM). The SEM was used to analyze the post-pulse ablation spots to determine the volume of fuel ablated. The micro-laser plasma thruster (micro-LPT) discussed here ablates a target material through the back surface by focusing the laser through a transparent substrate in a process typically referred to as Transmissive mode (T-mode) ablation. The target materials investigated were polyvinyl chloride (PVC) and glycidyl azide polymer (GAP), while the substrates used were cellulose acetate and Kapton(Tradename). Peak ion densities for a GAP (target)/acetate (substrate) were found to be 1.6x10(exp 7)/cu cm, while for GAP/kapton and PVC/acetate the peak ion densities were 4.5x10(exp 7)/cu cm and 7.9x10(exp 9)/cu cm respectively. Although these corresponded to low ionization fractions calculated from the observed mass loss, the results indicate there are ways to improve the ionization fraction and in turn increase the specific impulse.

Measured highly elevated gains of proton–boron (HB11) fusion (Picciotto et al., Phys. Rev. X 4, 031030 (2014)) confirmed the exceptional avalanche reaction process (Lalousis et al., Laser Part. Beams 32, 409 (2014); Hora et al., Laser Part. Beams 33, 607 (2015)) for the combination of the non-thermal block ignition using ultrahigh intensity laser pulses of picoseconds duration. The ultrahigh acceleration above $10^{20}~\text{cm}~\text{s}^{-2}$ for plasma blocks was theoretically and numerically predicted since 1978 (Hora, Physics of Laser Driven Plasmas (Wiley, 1981), pp. 178 and 179) and measured (Sauerbrey, Phys. Plasmas 3, 4712 (1996)) in exact agreement (Hora et al., Phys. Plasmas 14, 072701 (2007)) when the dominating force was overcoming thermal processes. This is based on Maxwell’s stress tensor by the dielectric properties of plasma leading to the nonlinear (ponderomotive) force $f_{\text{NL}}$ resulting in ultra-fast expanding plasma blocks by a dielectric explosion. Combining this with measured ultrahigh magnetic fields and the avalanche process opens an option for an environmentally absolute clean and economic boron fusion power reactor. This is supported also by other experiments with very high HB11 reactions under different conditions (Labaune et al., Nature Commun. 4, 2506 (2013)).

A fuel cell (FC) using liquid fuel and oxidizer is under investigation. H2O2 is used in this FC directly at the cathode. Either of two types of reactant, namely a gas-phase hydrogen or an aqueous NaBH4 solution, are utilized as fuel at the anode. Experiments demonstrate that the direct utilization of H2O2 and NaBH4 at the electrodes results in >30% higher voltage output compared to the ordinary H2/O2 FC. Further, the use of this combination of all liquid fuels, provides numerous advantages (ease of storage, reduced pumping requirements, simplified heat removal, etc.) from an operational point of view. This design is inherently compact compared to other cells that use gas phase reactants. Further, regeneration is possible using an electrical input, e.g. from power lines or a solar panel. While the peroxide-based FC is ideally suited for applications such as space power where air is not available and a high energy density fuel is essential, other distributed and mobile power uses are of interest.

An alternative way may be possible for igniting solid density hydrogen- 11 B (HB11) fuel. The use of >petawatt-ps laser pulses from the non-thermal ignition based on ultrahigh acceleration of plasma blocks by the nonlinear (ponderomotive) force, has to be combined with the measured ultrahigh magnetic fields in the 10 kilotesla range for cylindrical trapping. The evaluation of measured alpha particles from HB11 reactions arrives at the conclusion that apart from the usual binary nuclear reactions, secondary reactions by an avalanche multiplication may cause the high gains, even much higher than from deuterium tritium fusion. This may be leading to a concept of clean economic power generation.

We report the discovery of a new optical-IR synchrotron jet in the radio galaxy 3C 133 from our HST NICMOS snapshot survey. The jet and eastern hot spot are well resolved and visible at both optical and IR wavelengths. The IR jet follows the morphology of the inner part of the radio jet, with three distinct knots identified with features in the radio. The radio-IR SEDs of the knots are examined, along with those of two more distant hot spots at the eastern extreme of the radio feature. The detected emission appears to be synchrotron, with peaks in the NIR for all except one case, which exhibits a power-law spectrum throughout.

It seemed to be an impossible task thirty years ago to shine a laser beam on uncompressed solid DT and to ignite a fusion flame since the necessary energy flux densities are in the range of more than 100MJ/cm 2 or corresponding deuterium ion current densities above 10 10 Amp/cm 2 which conditions were completely out of range. Since PW-ps laser pulses are available now, the situation has changed, however, by inclusion of a very sophisticated method for suppressing prepulses such that relativistic self-focusing is avoided and a purely plane or similar geometry interaction as a skin layer process appears. Out of the wide stream of research, only very special experiments with clear laser pulses confirmed this kind of interaction in theoretical and numerical agreement. This leads to the space-charge neutral plasma blocks or pistons generated by the nonlinear (ponderomotive) acceleration for producing the necessary ion current densities for the optimized ion energies of 80 keV to irradiate solid state DT. While numerous further properties have to be evaluated, the aim seems to be attractive for the very low cost fusion energy production by laser irradiation.

Generation of high speed dense plasma blocks is well known from hydrodynamic theory and computations (PIC) with experimental confirmation by Badziaket al.(2005) since ps laser pulses with power above TW are available. These blocks may be used for fusion flame generation (thermonuclear propagation) in uncompressed solid state deuterium and tritium for very high gain uncomplicated operation in power stations. Hydrodynamic theory from computations from the end of 1970s to recent, genuine two fluid computations support the skin layer accelerations (SLA), by nonlinear (ponderomotive) forces as measured now in details under the uniquely selected conditions to suppress relativistic self-focusing by high contrast ratio and to keep plane geometry interaction. It is shown how the now available PW-ps laser pulses may provide the very extreme conditions for generating the fusion flames in solid state density DT.

Studies of single-event laser-target interaction for fusion reaction schemes leading to volume ignition are discussed. Conditions were explored where single-event ns-laser pulses give rise to temperatures sufficient for volume ignition. Thus, ignition is possible, particularly if X-ray reabsorption is sufficiently high. Unfortunately, this scheme requires laser pulses with energies above 5 MJ and target densities of compressed DT above 1000 g/cm−3. Both requirements are quite demanding for near term systems. Nevertheless the present state technology and the detailed knowledge about volume ignition at direct drive are a basis. Systems as NIF or LMJ can well confirm these physics-clarified conditions and the technology for large laser systems with sufficient repetition rate and for a drastic reduction of the size and costs is necessary and possible and by physics similar to the known reductions in transistor development.

The DD reaction yield (3-MeV protons) and the soft X-ray emission from a titanium (Ti) cathode surface in a periodic pulsed glow discharge in deuterium were studied at a discharge voltage of 0.8–2.45 kV and a discharge current density of 300–600 mA/cm2. The electron screening potential Ue = 610 ± 150 eV was estimated in the range of deuteron energies 0.8 keV < Ed < 2.45 keV from an analysis of the DD reaction yield as a function of the accelerating voltage. The obtained data show evidence for a significant enhancement of the DD reaction yield in Ti in comparison to both theoretical estimates (based on the extrapolation of the known DD reaction cross section for Ed ≥ 5 keV to low deuteron energies in the Bosch-Halle approximation) and the results of experiments using accelerators at the deuteron energies Elab ≥ 2.5 keV and current densities 50–500 μ A/cm2. Intense emission of soft X-ray quanta (1013–1014 s−1 cm−2) was observed at an average energy of 1.2–1.5 keV. The X-ray emission intensity and the DD reaction yield enhancement strongly depend on the rate of deuterium diffusion in a thin subsurface layer of Ti cathode.

The discovery of the essential difference of maximum ion energy for TW - ps laser plasma interaction compared with the 100 ns laser pulses [1] led to the theory of a skin layer model [2] where the control of prepulses suppressed the usual relativistic self-focusing. The subsequent generation of two nonlinear force driven blocks has been demonstrated experimentally and in extensive numerical studies where one block moves against the laser light and the other block into the irradiated target. These blocks of nearly solid state density DT plasma correspond to ion beam current densities [3] exceeding 1010 A/cm2 where the ion velocity can be chosen up to highly relativistic values. Using the results of the expected ignition of DT fuel by light ion beams, a self-sustained fusion reaction front may be generated even into uncompressed solid DT fuel similar to the Nuckolls-Wood [4] scheme where 10 kJ laser pulses produce 100 MJ fusion energy. This new and simplified scheme of laser-ICF needs and optimisation of the involved parameters.

Compression of plasmas with laser pulses in the 10-kJ range produced densities in the range of 1000 times that of the solid state, where however the temperatures within a few hundred eV were rather low. This induced the fast ignitor scheme for central or peripheral deposition of some 10-kJ ps laser pulses on conventional $n_{\rm s}$-precompressed DT plasma of 3000 times solid-state density. We present results where the ps ignition is avoided and only a single-event conventional compression is used. Following our computations of volume ignition and the excellent agreement with measured highest fusion gains of volume compression, we found conditions where compression to 5000 times that of the solid state and by using laser pulses of 10 MJ produce volume ignition with temperatures between 400 and 800 eV only for high-gain volume ignition.

In previous chapters, we have reviewed pumping methods for gas-medium and condensed-medium lasers using nuclear reactors as neutron sources. We also reviewed the characteristics of these lasers and the potential to use them in different nuclear-laser devices. The highest specific power depositions for gas media (q ≤ 5 kW/cm3) can be obtained if a laser cell that has a uranium layer or is filled with 3Не is placed inside the core of a pulsed reactor at the minimal possible pulse length for pulsed reactors, ~100 μs. However, these specific power depositions are sometimes not sufficient to reach the lasing threshold of certain active media.

At present, direct nuclear pumping is implemented for gas laser media in which the populating of lasing levels occurs as a result of processes occurring in a high-pressure low-temperature plasma formed by ionizing radiation. Sometimes this plasma is called nuclear-excited plasma.

In Chap. 2 we examined rather simple NPL designs for searching for and studying characteristics of laser active media, but there are also more complex nuclear laser devices. As a rule, they are structural elements of multichannel reactor lasers operating in stationary or pulsed modes, and are intended to study the specifics of their operation. This chapter examines some of these devices, whether in operation or still being designed.

Chapter 6 gives a brief overview of designs for nuclear laser setups with a pulse duration of ~10 ms (OKUYAN and LIRA setups). Their operation is based on the “initiating reactor–subcritical laser block” scheme. The literature has repeatedly suggested different design schemes for stationary nuclear laser facilities or reactor-laser (RL) based on gas laser media. The term RL was apparently first proposed in article [1], where the potential of removing energy in the form of laser radiation from the reactor core during the relaxation stage was noted in principle. The most interesting version of the RL is a device where, as a consequence of spatial overlapping of the nuclear fuel and laser medium, a significant portion of the nuclear energy is converted into laser radiation bypassing the intermediate thermal energy stage.

Investigations of optical inhomogeneities in sealed NPLs have revealed that flowing of the gas medium through the laser cavity is a necessary condition for achieving CW lasing in the stationary and quasi-stationary excitation modes. Gas heating is a no less important factor that requires the implementation of gas flowing.

This book primarily discusses NPL research in Russia. The Russian program has been larger and remains active whereas work in the United States and elsewhere has dwindled. Shortly after the end of the Cold War, two circumstances combined to cause stoppage of NPL work. While the military need ceased, public opposition to nuclear power mounted following the Three Mile Island Nuclear reactor accident in the United States. Such concerns clearly carried over to a reactor pumped laser, i.e. to NPLs. Here we briefly review earlier work is the United States, prior to a build-up of effort as part of the “Star Wars” program as cold war tension grew.

The short range of fission fragments causes a specific energy input inhomogeneities which, along with excited gas heat exchange with laser cell walls, leads to density spatial redistribution, i.e., to the violation of active medium optical homogeneity. As noted in paper [1], with a reference to the 1980 report of A. N. Sizov and Yu. N. Deryugin, numerical and theoretical investigations of the dynamics of optical inhomogeneity origination and development in nuclear pumping lasers first began at the VNIIEF. During phase one, these investigations only pertained to the phenomena occurring in sealed lasers excited by pulsed neutron fluxes. This important aspect of NPLs is discussed in this chapter.

Virtually all of the experimental investigations to seek and study the characteristics of NPLs excited by the products of nuclear reactions were carried out on pulsed nuclear reactors. Pulsed nuclear reactors are distinguished for the composition and structure of their core, the duration and fluence of the neutron pulse, the volume and configuration of the space for the irradiation, and the pulse repetition frequency. Some aspects of the use of pulsed reactors for laser pumping were examined in the survey [1]. This section uses some of the data from study [1], supplemented by information from other sources.

This chapter examines the kinetics of plasmochemical processes and the lasing mechanisms of various types of gas NPLs pumped using neutrons from pulsed nuclear reactors. The lasers considered here typically have Continuous Wave, i.e. CW operation (or, more accurately, quasi-CW) lasing mechanisms, because the characteristic times of basic plasma processes are much less than the durations of pulsed reactor pumping pulses (≥50 μs). To determine the lasing mechanism, it is necessary to ascertain the processes of populating and quenching both of the upper and of the lower lasing levels. Information about the specific features and the constants of the most important plasmochemical processes is contained in a number of studies (see [1–4], for example).

Double-well potential structure (virtual cathode formation) is studied in a spherical inertial electrostatic confinement (SIEC) device using non-linear Poisson's equation. Particle densities are derived from a kinetic equation equivalent to Vlasov's equation. Velocities of collision-free electrons and ions at the edge of the configuration will be almost aligned towards the center, however, they have small divergences. Analyses show appearance of a virtual cathode potential well relevant to burn fusion fuels near the center of SIEC.

The spherical inertial-electrostatic confinement (SIEC) concept is designed to focus and accelerate ions and electrons radially inward towards the center of a negatively biased, highly transparent spherical grid. The converging ions create a high-density plasma core where a high fusion rate occurs. In addition, under proper conditions, the ion and electron flows create a space-charge induced "double potential" well (a negative potential well nested inside a positive potential well). This structure traps high-energy ions within the virtual anode created by the double potential, providing a high fusion density in the trap volume. The present experiment was designed to verify double potential well formation and trapping by a measurement of the radial birth profile of energetic (3-MeV) protons produced by D-D fusion reactions in a deuterium discharge. This experiment was designed to operate at high perveance (0.4 to 1.4 mA/kV/sup 3/2/), where formation of a double well is predicted theoretically. Additional steps to aid well formation included: use of the unique Star mode of operation to obtain ion beam focusing down to -1.6 H the ballistic limit and the incorporation of a second electrically "floating" grid (in addition to the focusing/accelerating cathode grid) to reduce the ion radial energy spread to 0.34 mA/kV/sup 3/2/. As the perveance increased, the depth of the double well also increased. At the maximum perveance studied, 1.38 mA/kV/sup 3/2/ (corresponding to 80 mA and 15 kV), the negative potential well depth, corresponding to the measured proton-rate density, was estimated to be 22%-27% of the applied cathode voltage. This represents the first conclusive demonstration of double well formation in an SIEC, since prior measurements by other researchers typically yielded marginal or negative results.

Anomalous interaction of terawatt-picosecond laser pulses allows side-on ignition of solid state density fusion fuel with the unexpected possibility of igniting uncompressed hydrogen–boron p11 B. Suppression of relativistic self-focusing by using very clean laser pulses with an extremely high contrast ratio is essential to achieve ignition thresholds only ten times more difficult than fusion of deuterium–tritium (DT). This opens the possibility for laser driven fusion energy without neutrons and less radioactivity than from burning coal. The complex nonlinear optical properties involved are elaborated.

This paper summarizes some of the main conclusions and highlights of the Emerging Concepts Working Group (EC Group) of the Snowmass 1999 Fusion Summer Study. The EC Group considered technical challenges and opportunities related to emerging concept issues.

The influence of controlled sawteeth on thermal helium exhaust is explored using the BALDUR 11/2-dimensional transport code for an ARIES-I-type plasma. Sawteeth are shown to be useful for removing thermal helium from the central region to the outer region of a tokamak plasma. Outer region transport enhancement is found essential for removing the ash from the outer region. It is found that the optimal sawtooth period to give the minimum thermal helium level (or maximum fusion power) is several times larger than the fast alpha-particle slowing-down time for an ARIES-I-type driven plasma. With a sawtooth period of ∼5 s and helium transport selectively enhanced by one order of magnitude relative to the diffusion of hydrogenic ions, the fusion power increases ∼30% compared to the case without sawteeth/without enhancement. It is also found that sawteeth combined with outer region transport enhancement have the potential to advantageously reduce the helium concentration.

This book is dedicated to the field of inertial electrostatic confinement (IEC) fusion. Confinement of a hot plasma for fusion or plasma processing is difficult because the hot plasma prevents use of a material confinement vessel. IEC fusion is one of the various methods that can be used to confine a hot fusion plasma. As will be apparent from this book, IEC fusion offers many potential advantages, including simplified support structures and the ability to create non-Maxwellian plasmas that can be used with a variety of fusion fuels. However, a majority of fusion scientists are studying magnetic field confinement in the form of a closed torus (e.g., a Tokamak). Alternately, the fast pulsed approach used in laser fusion attempts to rapidly compress the plasma to an ultrahigh density, and the inertia of the ions maintains the high density long enough such that the fusion energy produced exceeds the input compression energy. Thus, this approach was termed inertial confinement fusion (ICF). These two approaches have led to current major fusion experiments: the international ITER Tokamak in France and the National Ignition Fusion (NIF) experiment using a laser at the Lawrence Livermore National Laboratory (LLNL). Both confinement approaches require very large and complex units, costing billions of dollars to construct. A number of alternate confinement concepts have been proposed with the objective of achieving smaller, less expensive power plants. Some also have the objective of burning “advanced fuels,” defined loosely as any non-D–T fuels [1]. Examples include deuterium–deuterium (D–D), deuterium–helium-3 (D–3He), and hyrdrogen–boron-11 (H–B11). One objective of using such fuels is to minimize neutron production, thus neutron-induced radioactivity and damage in structural materials. A second objective is to reduce or eliminate the need for tritium handling and breeding, greatly simplifying the chamber blanket systems. Hydrogen–boron-11 (or H–B11, often termed p–B11) is ideal with a plentiful fuel supply and a reaction that produces three energetic alpha particles with no neutron (hence aneutronic). However, burning p–B11 generally requires very high ion temperatures (~ 170 keV vs. ~ 25 keV for D–T) and low electron temperatures (< 1/5 the ion temperature), plus elimination of magnetic fields within the hot fusing plasma to minimize Bremsstrahlung and cyclotron radiation losses, respectively. The IEC is one of only a few alternate confinement approaches that theoretically offer the highly non-Maxwellian plasma conditions needed to burn p–B11. Experimental demonstration of this is a key objective for IEC experiments but is very challenging, as discussed in later chapters.

Grid design and construction are a vital part of the IEC. In this chapter we concentrate on grids for spherical IEC systems. Similar considerations carry over to other geometries, e.g., cylindrical IECs. There are several factors that must be taken into consideration in doing this. First, the wire used for the construction of the cathode has to be a suitable material to supply the strength needed, have a high melting temperature, and control electron emission. Second, from the earlier discussion we know that the effective transparency is more important than the physical transparency of a cathode. Thus, ideally the cathode grid should be constructed in such a way that the openings in the cathode radially face each other with good symmetry and with openings of sufficient size to support formation of ion microchannels. Third, the overall size and shape of the cathode grid plays a significant role in the performance of the device and should be taken into consideration while designing a grid. This chapter concentrates on selection of grid materials and construction.

Grid geometry plays an important role in the performance of a gridded spherical IEC device because the ion recirculation, and hence the reaction rate, is strongly affected by the orientation and size of openings in the cathode in grid design. In Chap. 3 we learned that cathodes with reasonably large openings face each other so that an ion could easily recirculate via ion microchannels (corresponding to a high effective transparency) and perform much better than either a solid cathode or a cathode with holes that do not point directly at each other (i.e., causing a low effective transparency). Aside from these major features, various researchers have investigated the effect of a variety of grid opening geometries [1]. However, these experiments have been generally inconclusive, because they operated in the grid performance “saturation” regime, wherein the maximum symmetry is already achieved and any further increase in symmetry through addition of more wires does not cause significant improvement in the observed reaction rate.