The possibility of enhancement of molecular formation by strong electromagnetic fields is discussed. The electron screening of the laser is considered. Rate production of ddμ and dtμ molecules in the presence of a laser field is estimated as a function of the resonance detuning.

A two-dimensional hydrodynamic code is discussed. It includes the treatment of energy deposition by heavy ions and the calculation of transport coefficients. Loss terms due to volume radiation in the emission limit and a realistic equation of state (SESAME tables or the equation of state of an ionized gas including the solution of the Saha equations to determine the degree of ionization) are considered.

Numerical simulations are performed to study the hydrodynamic flow in cylindrical tubes filled with the noble gases Argon and Xenon respectively. Target and beam parameters are chosen in close analogy to the GSI-RFQ beam-target experiments.

The conditions for the formation of a shock wave at the interface between matter heated by the ion beam and cold matter are investigated. It turns out that, in addition to ionization effects, shock heating has a strong influence on the maximum target temperature. Depending on the temperatures to be reached with a given deposition power, either expansion or radiation cooling could be the dominant cooling mechanism. As a result we can conclude that hydrodynamic motion produces a lot of structure that should be observable in the GSI experiments.

In order to enhance the coupling efficiency, a low Z ablator is generally used for ICF targets. The ablator thickness is appropriately chosen so it is burned out by the end of a laser pulse. Then all of the implosion kinetic energy is contained in the DT fuel. However, a small amount of preheating degrades the compression in a hollow shell, DT fueled target implosion. In this paper, we investigate the preheating level of the fuel shell by Fokker–Planck simulations of the electron heat transport.

From the analysis, it is found that a thick surface layer of a laser irradiated low-Z target is preheated by Maxwellian tail electrons which have a long mean free path. Hence, we propose that the target be precompressed by a tailored pulse, in order to increase the shell ρΔR at the laser peak.

The emission spectra of HgBr (B–X) band system and atomic mercury lines have been observed during collisions involving O+/ and HgBr2 in the kinetic energy (lab.) range of 100–1000 eV.

Emissions from the rear side of the targets were temporally resolved by irradiating an ultraviolet (UV) laser on Al and Au thin targets. A difference was clearly observed between the above two targets. Given the fact that absorbed laser energy is converted with a very high efficiency to soft x-rays in a high Z plasma, a characteristic emission peak only observed for Au targets was attributed to the effect of soft x-ray energy transport. The ablation pressures estimated from the emissions indicate that the pressure scaling for Au is close to the one by x-ray radiation rather than by a UV laser. With soft x-ray irradiation, energy transport in A1 foils was also studied. An ablation pressure was estimated by the shock speed.

We have completed the conceptual design of a 170-MJ laser system consisting of two identical, opposing, 0·4 M-litre, 84-MJ HF subsystems, which together deliver 105 ‘useful’ MJ in 50 ns (FWHM duration) to a laser-fusion target during its hydrodynamic drive interval. We achieved extreme design simplicity by eliminating most optics, using an inexpensive, very-high-energy-density gain medium, propagating the laser beam at the maximum fluence permitted by optical breakdown in the laser medium, and by using replicated simple subsystems for pulsed power. The infrared spectrum of the HF laser lies outside the ultraviolet range favored by the U.S. laser fusion program for optimum target coupling efficiency. However, the laser architecture we describe is an alternative for laser fusion systems which offers dramatic improvements in simplicity, compactness, and efficiency, which advantages will be even more pronounced when equally efficient, visible-wavelength chemical lasers become available.

When a one-shell three-layer cryogenic target is irradiated by a driver beam of total energy 10 MJ and pulse width 30 ns, the pusher pressure increases to 1013 Pa, accelerating fuel toward target center, and the fuel implosion velocity reaches 3 × 105 m/s. A spherical hollow target plays the role of a supersonic converging nozzle, and the fuel is compressed to 269 times the solid density in the supersonic region and to 3·51 × 104 times in subsonic region. Nonuniform beam-energy-deposition in pusher layer causes nonuniform pusher pressure and hence nonuniform implosion, which reduces fuel compression significantly. The smoothing of pusher pressure by radiative energy transfer, or gas-filled target instead of cryogenic hollow target can be used to reduce the defect of nonuniform implosion. At last, the structure of an indirect driven target is proposed to smooth out pusher pressure in spite of nonuniform beam irradiation.

Volume compression and volume ignition of laser compressed pellets has an enormous advantage against spark ignition since the alpha self-heat substantially contributes as an additional stimulation of nuclear fusion reactions. We present here improved computations of volume ignition in agreement with the classical fact that the generated fusion energy is larger than the bremsstrahlung energy in DT only at temperatures above 4·5 keV. This result is in very close agreement with Kidder's (1974) values, and in agreement with recent computations of Mima et al. (1987). The extension of these calculations to higher densities and input energies results in the self-absorption of bremsstrahlung at an initial temperature of about 1 keV only, much below the classical 4·5 keV. A fuel burnup fraction above 80% is shown to be possible.

The main tool for the laser plasma work at MPQ (Max-Planck-Institut für Quantenoptik) is the ASTERIX iodine laser delivering 300 J/300 ps pulses at 1·3 m, operational also at 2ω and 3ω. A fifth 30-cm diameter am lifier is under construction to increase the pulse energy up to 2 kJ.

Soft X-ray radiation emitted by laser plasmas and its influence on energy transport and hydrodynamics is studied. Time and space resolved spectroscopic measurements of soft X-radiation from a variety of targets are compared with analytical models and computer results. Planck radiation is produced in gold cavities to study radiation hydrodynamics. Theoretical work comprises shock waves in solids, the electronic structure of very high density matter, radiation pumped X-ray laser and development of the appropriate computer codes.

Estimates indicate that dense plasmas with temperatures of several ten keV can be produced with the heavy ion accelerator now under construction at GSI-Darmstadt. Experiments are being prepared to be started in 1991. Measurements at the present UNILAC-accelerator confirm the theoretical prediction that the energy loss of heavy ions in a plasma is much higher than in cold matter.

When an extremely high pressure gas is irradiated by an intense laser light, a dense plasma produced at the focal spot moves towards the focusing lens with a high velocity. Making use of this phenomenon, a new plasma-bridged gap switch is proposed and its switching characteristics is experimentally examined. From the experiments, it is confirmed that the switching time is almost constant with the applied voltage only when the focal spot is just on the positive electrode, indicating that the bridging of gap is caused by the laser light.

Lithography techniques hold the key to achieving ultra large-scale integration (ULSI) and they have been a major research subject. For fabrication of ULSI devices, a quarter micron or smaller pattern delineation with nanometer scale accuracy is required. Various techniques using electron, ion and photon beams have been investigated to fulfill these requirements. The present paper discusses the characteristics of several key lithography techniques and their limitations.

Strong ionization in metal vapors is known to be very readily produced by a variety of pulsed and CW lasers. Particularly well known is ‘resonance’ ionization by pulsed or CW dye lasers operated at the atomic resonance lines (e.g. Na 3s → 3p). We also have experimental results for two other forms of ionization: ‘quasiresonant’ ionization using a CW dye laser (e.g. at the Na 3p → 4d transitions), and ‘two-photon resonance’ ionization using a pulsed dye laser (e.g. at the Na 3s → 4d two-photon resonances). Both new forms are visually characterized by bright ‘white sparks’ and correspond to reasonably high electron densities of ∼1014−1015 cm3 and low electron temperatures of ∼0·1−0·2 eV. The ‘quasiresonant’ ionization is remarkable in that it occurs even with a very low power 1 mW focused CW laser in 10 torr of Na. A variety of interesting atomic and molecular spectroscopic features have been observed and analyzed.