P. Lalousis

Density modification and energetic ion production at relativistic self‐focusing of laser beams in plasmas

A two‐dimensional time‐dependent laser plasma interaction code is described and used to model the interaction between a 5 psec Nd glass laser pulse of peak power 1013 W and a 35 times ionized tin target. Parameters are chosen so that relativistic self‐focusing down to a diameter of the order of the wavelength of the laser light is observed in a distance comparable to the half intensity vacuum beam diameter. At later times strong modification of the plasma density by the nonlinear force is observed. The combination of relativistic self‐focusing and axial nonlinear force results in the acceleration of tin ions to a maximum energy of 5 GeV, in agreement with previous approximate calculations.

Fusion energy using avalanche increased boron reactions for block-ignition by ultrahigh power picosecond laser pulses—ERRATUM

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.

On the surface tension of plasmas

The electric field energy in the inhomogeneous surface of a plasma (due to the presence of a double layer at the surface) divided by the surface area defines a surface tension. Two cases of interest are studied. First, the magnitude of the surface tension for a thermally produced double plasma layer is evaluated. Secondly, the surface tension for a double layer at the surface of a degenerate electron gas in a metallic ion lattice is evaluated. The results are in fair agreement with the measured surface tensions. A numerical hydrodynamic evaluation of the surface tension for the particular case of laser-plasma interaction is given, as well as discussions on the stabilization of the Rayleigh-Taylor instability and the charging of spherical plasmas. The theory may find application to laboratory and cosmic plasmas when regions of different plasma densities and temperatures are sufficiently delineated by thin surfaces of charge separation. >

Ultrahigh acceleration of plasma by picosecond terawatt laser pulses for fast ignition of fusion

A fundamental different mechanism dominates laser interaction with picosecond-terawatt pulses in contrast to the thermalpressure processes with ns pulses. At ps-interaction, the thermal effects are mostly diminished and the nonlinear (ponderomotive) forces convert laser energy instantly with nearly 100% efficiency into the space charge neutral electron cloud, whose motion is determined by the inertia of the attached ion cloud. These facts were realized only by steps in the past and are expressed by the ultrahigh plasma acceleration, which is more than few thousand times higher than observed by any thermokinetic mechanism. The subsequent application for side-on ignition of uncompressed fusion fuel by the ultrahigh accelerated plasma blocks is studied for the first time by using the genuine two-fluid hydrodynamics. Details of the shock-like flame propagation can be evaluated for the transition to ignition conditions at velocities near 2000 km/s for solid deuterium-tritium.

Hydrodynamic Analysis of the High Electrc Fields and Double Layers in Expanding Inhomogeneous Plasmas

A genuine two-fluid model of plasmas with collisions permits the calculation of dynamic electric fields and double layers inside of plasmas including oscillations and damping. For the first time, a macroscopic model for coupling of electromagnetic and Langmuir waves was achieved with realistic damping. Starting points were laser-produced plasmas showing very high dynamic electric fields in nonlinear force-produced cavitons and inverted layers, in agreement with experiments. Applications for any inhomogeneous plasma as in laboratory or in astrophysical plasmas can then be followed up by a transparent hydrodynamic description. We find the rotation of plasmas in magnetic fields and a new second harmonic resonance. Explanation of inverted double layers, second harmonic emission from laser-produced plasmas, and laser acceleration of charged particles by the very high fields of the double layers is given.

Fiber ICAN laser with exawatt-picosecond pulses for fusion without nuclear radiation problems

One of the numerous applications of the ICAN laser using the advantage of fiber optics with chirped pulse amplification (CPA), is the scheme of side-on initiation of a nuclear fusion flame in solid density fuel with laser pulses of shorter than picosecond (ps) duration and power in the petawatt (PW) and higher range. The ICAN Fiber optics has special advantages with the potential that >900 PW spherical laser pulses may ignite the proton reaction with 11 B (HB11) without the problem of dangerous radioactive radiation. Though secondary reactions can be estimated very roughly, the feasibility of a power station with the necessary energy gains can be concluded.

High electrostatic fields at ponderomotive laser driving of plasmas by nonlinear forces

Abstract The very short time step numerical two-fluid computation of laser-plasma interaction including complete nonlinear optical constants and the nonlinear (ponderomotive) force results in detailed information on plasma oscillations and damping and in the generation of electrostatic fields of 10 8 V/cm for neodymium glass laser pulses of 10 16 W/cm 2 intensity. The decoupling of interaction after caviton generation occurs as in preceding one-fluid calculations, after having permitted sufficient nonlinear force pushing of shells for fusion.

Beam smoothing and temporal effects:Optimized preparation of laser beams for direct-drive inertial confinement fusion

Direct-drive laser fusion received a number of setbacks from the experimental observation in the 1960s and 1970s of very complex interactions in laser plasma experiments caused by a number of nonlinear and anomalous phenomena. Although smoothing methods were introduced intuitively or empirically - succeeding in reducing these difficulties - it was not until a few years ago that the 20-ps stochastic pulsation mechanism was discovered. We assume here that this 20-ps stochastic pulsation may be the major obstacle to achieving direct-drive fusion, even though it is now generally assumed that the major challenge to the achievement of direct-drive fusion is the Rayleigh-Taylor instability. While we do not discount the importance of the Rayleigh-Taylor mechanisms, we concentrate here on the analysis of the pulsation process. A method of analysis was developed, using time-dependent real-time computations employing a genuine two-fluid model, which includes the interior electric fields and the very large amplitude longitudinal plasma oscillations that are driven by the laser field. These mechanisms, which were first suggested in 1974, reveal themselves now as self-generated von-Laue gratings, preventing the propagation of laser radiation through the outermost plasma corona and preventing energy deposition by temporal interruption caused by thermal relaxation and the subsequent reestablishment of these gratings, and so on. The abolition of this pulsation by broad-band laser irradiation or other smoothing methods is now well understood. A synopsis of these developments is presented here, consistent with Rubbias proposition of using the MJ drivers for laser fusion, the technology for which is now available.

A LIF scheme for HIPER application based on the combination of ultrahigh laser nonlinear force driven plasma blocks and the relativistic acceleration of ions blocks

Laser ignition of fusion (LIF) of light nuclei for fusion reactions for producing energy (LIFE) by using very powerful laser pulses with duration in the range of picoseconds is the aim of fast ignition where HiPER is one of the options. Special attention is given to the ultrahigh acceleration of plasma blocks about which option results are reported including an alternative scheme for avoiding lateral energy losses. Examples of relativistic accelerations are evaluated for HiPER and LIFE applications.

Road map to clean energy using laser beam ignition of boron-hydrogen fusion

With the aim to overcome the problems of climatic changes and rising ocean levels, one option is to produce large-scale sustainable energy by nuclear fusion of hydrogen and other very light nuclei similar to the energy source of the sun. Sixty years of worldwide research for the ignition of the heavy hydrogen isotopes deuterium (D) and tritium (T) have come close to a breakthrough for ignition. The problem with the DT fusion is that generated neutrons are producing radioactive waste. One exception as the ideal clean fusion process – without neutron production – is the fusion of hydrogen (H) with the boron isotope 11 B11 (B11). In this paper, we have mapped out our research based on recent experiments and simulations for a new energy source. We suggest how HB11 fusion for a reactor can be used instead of the DT option. We have mapped out our HB11 fusion in the following way: (i) The acceleration of a plasma block with a laser beam with the power and time duration of the order of 10 petawatts and one picosecond accordingly. (ii) A plasma confinement by a magnetic field of the order of a few kiloteslas created by a second laser beam with a pulse duration of a few nanoseconds (ns). (iii) The highly increased fusion of HB11 relative to present DT fusion is possible due to the alphas avalanche created in this process. (iv) The conversion of the output charged alpha particles directly to electricity. (v) To prove the above ideas, our simulations show for example that 14 milligram HB11 can produce 300 kWh energy if all achieved results are combined for the design of an absolutely clean power reactor producing low-cost energy.