The nuclear reaction of hydrogen (protons) with the boron isotope 11 (HB11) is aneutronic avoiding the production of dangerous neutrons in contrast to any other fusion but it is extremely difficult at thermal equilibrium plasma conditions. There are alternative schemes without thermal equilibrium, e.g. the Tri Alpha reversed magnetic field (RMF) confinement and others, however, the only historical first measurements of HB11 fusion were with lasers interacting with high density plasmas using non-thermal direct conversion of laser energy into ultrahigh acceleration of plasma blocks to avoid the thermal problems. Combining these long studied mechanisms with recently measured ultrahigh magnetic fields for trapping the reacting plasma arrives at a very compact design of an environmentally clean reactor for profitable low cost energy using present technologies.
An alternative way may be possible for igniting solid density hydrogen-11B (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.
Interaction of TW-ps laser with plasma results in a skin layer mechanism for nonlinear (ponderomotive) force driven two dimensional plasma blocks (pistons) if a very high contrast ratio is provided for suppression of relativistic self-focusing. This Skin layer acceleration (SLA) [1] results in space charge neutral plasma blocks with ion current densities larger than 1010 Amp/cm2 [1-3]. Using Ions in the MeV range results in 1000 times higher proton or DT current densities [3] than the proton fast igniter [4] is using and may result in better conditions of this fast ignitor scheme. Using ballistic focusing of the generated plasma blocks and a short time thermal expansion of these blocks for increasing their thickness while keeping the high ion current densities, results in conditions favourable for this option of fast ignition of a fusion target. Some details of the interaction processes are still to be analysed but the solutions studies to date are most encouraging.
It is being clarified why the observations of plane wave geometry interaction within the skin depth of a laser irradiated target are very unique exceptions from the broad stream of the usual experiments of laser plasma interaction. This permits a much more simplified description by plane wave interaction theory for laser pulses of about ps or shorter duration and powers above TW and simplifies computations in contrast to the usual cases with relativistic self-focusing. After establishing theoretically and experimentally the generation of highly directed plasma blocks with ion current densities above 1010 A/cm2 moving against the laser light or into the target, applications for laser fusion, and a completely new improvement of ion sources for the next generation of accelerators are discussed.
Plasma emission or ablation from laser-irradiated targets shows very complicated properties. One novelty was observed at irradiation of neodymium glass laser pulses of ps duration and TW power if there was a very strong suppression of prepulses by a contrast ratio of about 108 until 100 ps before the main pulse arrived. The emitted ion maximum energy was more than 50 times below the values observed in all the comparable numerous experiments. The other anomaly is that the number of the fast ions did not change when the laser intensity varied by a factor 30. This permitted a separation of the usual effects of self-focusing and permitted an analysis fully based on simplified plane geometry as a skin layer interaction mechanism. The consequence is that plasma blocks are accelerated by the nonlinear (ponderomotive) force with ion current densities above 1010 A/cm2. This provides basically new aspects for laser fusion using uncompressed solid DT fuel and a new kind of x-ray laser process may be possible.
The studies of laser ablation have lead to a new theory of nuclei, endothermic nuclei generation and quark-gluon plasmas. The surface of ablated plasma expanding into vacuum after high power laser irradiation of targets, contains an electric double layer having the thickness of the Debye length. This led to the discovery of surface tension of plasmas and to the internal dynamic electric fields in all inhomogeneous plasmas. The surface causes stabilization by short length surface waves smoothing the expanding plasma plume. Generalizing this to the degenerate electrons in a metal with the Fermi energy instead of the temperature, resulted in the surface tension of metals in agreement with measurements. Taking then the Fermi energy in the Debye length for nucleons results in a theory of nuclei with stable confinement of protons and neutrons just at the well known nuclear density, and in the Debye length equal to Hofstadter's decay of the nuclear surface. Increasing the nuclear density by a factor of 6 leads to the change of the Fermi energy into its relativistic branch where no surface energy is possible and the particle mass is not defined, permitting the quark-gluon plasma. Expansion of this higher density at the big band or in a supernova results in nucleation and element generation. The Boltzmann equilibrium permits the synthesis of nuclei even in the endothermic range limited to about uranium.
Inertial electrostatic confinement (IEC) devices offer a unique method to generate energetic ions for excitation of rare gas and rare gas halide excimers. A unique feature for this approach is that it allows small sized units with the ion source and excimer medium contained in vessels of order 30-cm radius. The IEC operates by applying a high negative voltage (up to -100 kV) on a spherical mesh grid (cathode) located in the center of a grounded grid (anode), all within a spherical vacuum vessel. A plasma discharge is created between the grids. The cathode extracts ions from the discharge and accelerates them towards the center of the device. Large ion background gas collision densities are created in the center region and along the ion beam paths, creating intense light emission. An alternate approach discussed here allow lower operating pressures and reduced ion thermalization, giving improved emission efficiencies, uses an external RF ion generator to separate the injected species from the mixture. The injector increases the device size, but a compact RF source has been developed which involves injector diameters of only ~ 6 cm by 30- cm length. Designs for such devices and their operation will be described.
A Nuclear Pumped Flashlamp (NPF) is closely related to a Nuclear-Pumped Laser NPL in that both use nuclear radiation to excite the medium. The NPF does not require as high peak power as is needed for NPL inversion. Still, with a reactor source, a large volume NPF can be designed to deliver extremely large fluorescence in the UV up to the infrared range, depending on the media employed. The NPF can then be used for industrial applications or for pumping a laser requiring a high intensity light pump. The first experimental example of this approach was a 3He-XeBr2 NPF employed in 1993 to pump a small iodine laser. The present paper discusses issues involved in scaling such a NPF up to an ultra high energy output.
Intense directional X-ray emission was observed from metal targets (Pd and Ti), which served as the cathodes in a pulsed high current (100-400 mA) and low voltage (1.0 - 2.0 keV) deuterium/hydrogen glow charge. X-ray measurements showed an intense (Ix = 1013-1014 s-1-cm-2) soft X-ray emission (with a mean energy of quantum Ex = 1.2-1.5 keV) directly from the Pd or Ti cathode. The X-ray yield is strongly dependent on a deuterium diffusivity in the surface layer of the cathode. The X-ray emission can be associated with enhanced electron screening effects at metal surfaces and interfaces and a coherent oscillation of this screening layer.
Due to pump source restrictions, Nuclear-Pumped Lasers (NPLs) typically have relatively long (micro- to milli-second) pulse lengths with only modest peak powers but with very high total energy. These pump power restraints seriously limit the choice of laser media. One way to avoid this problem is to employ a Nuclear Driven Flashlamp (NDF) for the primary pumped element in the system. The fluorescence from this NDF can then be used for pumping a laser or for other high intensity light applications. The first experimental example of this approach was a 3He-XeBr2 NDF employed by Williams and Miley (1993) to pump a small iodine laser. The present paper discusses issues involved in scaling such an NDF up to high power levels. Possible optimum configurations include use of microsphere or fiber pump elements dispersed in the NPF media. Analysis of such possibilities is presented along with consideration of special reflecting surface designs.
The Advanced Camera for Surveys (ACS) is a third generation instrument for the Hubble Space Telescope (HST). It is currently planned for installation in HST during the fourth servicing mission in Summer 2001. The ACS will have three cameras.
The O2-I2 transfer laser is gaining interest as a high-power laser for a variety of applications. There remains an interest in alternate pumping techniques for some situations, however. Here we review earlier work on the potential use of nuclear pumping, either for direct pumping of O2 or for pumping of an excimer flashlamp in a photolytic iodine laser system.
Nuclear-pumped lasers (NPLs) potentially offer an attractive method for high power laser applications such as a space power beaming. However, thermal gradients created by the pumping of the ion medium are producing a dynamic thermal blooming which must be understood and controlled for accurate beam control and focusing. In this paper, basic experimental studies of blooming under a variety of conditions are presented. It is shown that one promising approach for reducing the effect is to employ a combined volume-wall pumping technique.
The radiation-induced optical transmittance loss in polycrystal Csl was investigated in the 2.5- to 40-μm infrared region. Exposure of polycrystal Csl to ionizing radiation doses in the 0.3- to 1-Mrad range using a research reactor causes a significant degradation of the optical transmittance. Losses of up to 50% over the infrared transmiffance spectrum are reported; however, changes saturate at ⪅ 1 Mrad. The loss is particularly evident at shorter infrared wavelengths, shifting the threshold wavelength for transmittance to higher wavelengths. Results also show that cerium-doped polycrystal Csl exhibits improved radiation resistance.
The effect of thermal treatment and nuclear irradiation on the far infrared spectrum of polycrystal CsI was studied using pure and cerium doped crystals. Samples were exposed to neutrons and gamma radiation from a neutron activation tube. Thermal treatment was conducted in a 5.5 kilowatt furnace. Ionizing radiation caused significant infrared transmission losses at doses less than or equal to 1 MRad and the threshold wavelength of transmittance shifted to longer wavelengths. Transmission losses in cerium doped crystals were less than in pure crystals. Heat treatment also caused a significant reduction in transmittance. These results indicate that high temperature annealing will not decrease radiation damage.
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