No abstract

Saturation gain-length product during short-wavelength plasma lasing Appl. Phys. Lett. 101, 081105 (2012) Laser induced avalanche ionization in gases or gas mixtures with resonantly enhanced multiphoton ionization or femtosecond laser pulse pre-ionization Phys. Plasmas 19, 083508 (2012) A new scheme for stigmatic x-ray imaging with large magnification Rev. Sci. Instrum. 83, 10E527 (2012) Additional information on Phys. Fluids

The influence of small dc axial magnetic fields upon the stability of the focused plasma column is shown in the light of soft x rays. The material damage to the center electrode and the intense x-ray emission at the electrode face as a result of electron bombardment is considerably reduced. Although the final heating of the ions and electrons is inhibited as expected due to a trapped magnetic field, the spatial stability of the focused column offers a greater possibility for scaling to higher energies.

SYNOPSIS Care in the preparation and preservation of reagents, together with certain modifications in apparatus and technique, have eliminated the difficulties from plasma ammonia analysis. Ammonia contamination from the laboratory atmosphere has not proved an especial hazard, and no major setback has been encountered in the analysis of several thousand specimens over the last few years. The method has been found particularly suited to the performance of the occasional estimation, since, once prepared, all reagents are stable for a considerable time.The estimation of ammonia in blood has long been considered a difficult analysis and it has been stated that every investigation on the metabolism of ammonia is admittedly handicapped by the problem of methodology (Perea and Nelson, 1964). The commonly used methods of microdiffusion analysis are not well suited to the estimation of small quantities of ammonia in blood and to achieve the required sensitivity a most careful technique is needed to stretch the capacity of these methods to near their working limit.Although methods for the estimation of plasma ammonia by ion-exchange have been proposed for several years (Fenton, 1960(Fenton, , 1962Dienst, 1961) it does not seem widely recognized that methods based on this principle offer advantages in reproducibility and sensitivity not readily attainable by the microdiffusion technique.In an earlier communication a method was described for the estimation of plasma ammonia by ion exchange (Fenton, 1962), and in view of the long history of difficulty with blood ammonia analysis, special precautions were taken to eliminate those sources of artefact which were considered to be important hazards. This method has now been in routine daily use for several years and with the experience gained during this time, it has been found possible to simplify the technique and make improvements to both reagents and apparatus.The purpose of this account is to describe the modified method which is now used and to mention precautions which are necessary to obtain reliable results.Received for publication 30 May 1967. MATERIALS AND APPARATUSIt is essential that all distilled water is passed through a de-ionizing column to remove traces of ammonia and some metals. HEPARiN Dried heparin powder, 100,000 i.u. (Evans Medical Ltd.) is dissolved in 4 ml. water. The somewhat viscid solution is passed down one of the ion exchange columns which are used for plasma ammonia analysis. The ammonia-free effluent of heparin is collected and a further 1 ml. water is added to the column to displace the residuum. The final volume is made up to 5 ml.BLOOD COLLECTING TUBES The heparin solution is dispensed into 10 ml. polystyrene disposable tubes, each tube receiving a total of 400 i.u. Other anticoagulants are less satisfactory. ION Figure 1. These are a 10 ml. stoppered polystyrene disposable tube and a2 ml. polystyrene disposable syringe. The principle in the use of these columns is that the polystyrene tube acts as a reservoir; the hollow plunger of the...

The spectra and angular distributions of high-energy electrons emitted from laser-produced plasmas have been measured. The plasmas were produced using short pulses from both CO2 and Nd : glass lasers to irradiate polyethylene slabs. For a CO2 laser intensity of approximately 3×1014 W/cm2 we find at least an order of magnitude greater energy conversion to high-energy electrons than with a Nd : glass laser intensity of approximately 5×1015 W/cm2. The angular distribution of electron emission is strongly peaked along the target normal (i.e., density gradient) and fine angular structure is observed.