A system for analyzing constituents of coal-derived materials comprises three adsorption columns and a flow-control arrangement which permits separation of both aromatic and polar hydrocarbons by use of two eluent streams. 4 figures.

A low pressure ion source for a neutron source comprises a filament cathode and an anode ring. Approximately 150V is applied between the cathode and the anode. Other electrodes, including a heat shield, a reflector and an aperture plate with a focus electrode, are placed at intermediate potentials. Electrons from the filament drawn out by the plasma and eventually removed by the anode are contained in a magnetic field created by a magnet ring. Ions are formed by electron impact with deuterium or tritium and are extracted at the aperture in the focus electrode. The ion source will typically generate a 200 mA beam through a 1.25 cm/sup 2/ aperture for an arc current of 10A. For deuterium gas, the ion beam is over 50 percent D/sup +/ with less than 1% impurity. The current density profile across the aperture will typically be uniform to within 20%.

This invention teaches a control to be used in smelting aluminum by the electrolysis breakdown of alumina (Al/sub 2/O/sub 3/) in a molten electrolyte heated to approximately 950 to 1000/sup 0/C. The invention provides a sonic resonator and control that can accurately detect the resonant frequency of the resonator in the molten electrolyte. The resonator preferably is made with tubular side wall 1/4 of the sonic wavelength, or is a quarter wave resonator. A wave generator inputs a signal having a range of frequencies that includes the resonant frequency, so that a peak resonant output at the resonant frequency can be detected on an oscilloscope or like detector. This instantaneous resonant frequency is then checked against an accurate data base correlating the resonant frequencies of the resonator in the electrolyte at specific alumina concentrations normally experienced throughout the electrolysis cycle. The electrolysis cycle can thus be controlled and recharged at any predetermined low alumina concentration greater than where the anode effect phase of the cycle normally might begin.

A semiconductor liquid junction photocell in which the photocell is in the configuration of a light concentrator and in which the electrolytic solution both conducts current and facilitates the concentration of incident solar radiation onto the semiconductor. The photocell may be in the configuration of a non-imaging concentrator such as a compound parabolic concentrator, or an imaging concentrator such as a lens.

An improved method for the preparation of high purity rare earth sesquichalcogenides is described. The rare earth, as one or more pieces of the metal, is sealed under a vacuum with a stoichiometric amount of sulfur or selenium and a small amount of iodine into a quartz reaction vessel. The sealed vessel is then heated to above the vaporization temperature of the chalcogen and below the melting temperature of the rare earth metal and maintained until the product has been formed. The iodine is then vaporized off leaving a pure product. The rare earth sulfides and selenides thus formed are useful as semiconductors and as thermoelectric generators. 3 tables.