Development of beam position monitors for heavy ion recirculators
Work is underway at the Lawrence Livermore National Laboratory to design and build a small-scale, heavy ion recirculating induction accelerator. An essential part of this design work is the development of small non-intercepting diagnostics to measure beam current and position. This paper describes some of this work, with particular emphasis on the development of a small capacitive probe beam position monitor to resolve beam position to the 100 /spl mu/m level in a 6 cm diameter beam pipe. Initial measured results with an 80 keV potassium ion beam are presented.
Experiments in heavy ion fusion beam physics at LBNL, LLNL, and the University of Maryland
A heavy ion fusion driver must be capable of accelerating an intense ion beam to GeV beam energies. The final beam pulse current can be as high as a few kA using beam compression in an induction linac. Combining beamlets at low energy may prove to be economical as long as there is no significant emittance growth. Focusing of the final beam pulse from the reactor chamber wall to the target can be enhanced by using a plasma channel to guide the ion beam. Experiments at LBNL on ion sources, injector, the combiner and plasma channel focusing are discussed. One possible way to reduce the cost of a driver is to use an induction recirculator. Experiments at LLNL are exploring this concept by studying the transport and bending of space-charge-dominated ion beams. At the Univ. of Maryland the behavior of space-charge dominated beams is being simulated with low-energy electrons. They studied emittance growth, halo formation and beam pulse compression.
Full-scale measurements of SO2 gas phase concentrations and slurry compositions in a wet flue gas desulphurisation spray absorber
Abstract Two measurement campaigns were carried out at ENERGI E2's Asnaes Power plant, unit 5. The unit has a capacity of 620 MW e and is equipped with a wet flue gas desulphurisation (FGD) plant employing a counter-current spray absorber with five spray levels. In the first campaign, the power plant was firing Orimulsion ® with 2.85 wt% S resulting in a flue gas concentration of SO 2 exceeding 2000 ppmv. In the second campaign, the fuel applied was a low-S blended coal and the SO 2 concentration in the raw gas was around 400 ppmv. A novel probe for in situ sampling of gas phase concentrations in wet FGD spray absorbers was developed and applied for measuring axial profiles of the SO 2 gas phase concentrations in the absorber. The expected decrease in SO 2 concentrations along the height of the absorber was found in the spray section (from height 26.5 to 36.2 m) whereas the SO 2 concentration above the holding tank and below the gas inlet was quite low probably due to long local residence times in the region. Horizontal variations, due to somewhat different flow conditions near the column wall were investigated and the SO 2 concentrations were found to be higher near the wall. Measurements at different gross loads showed that the SO 2 gas phase concentration at a given position inside the absorber was roughly linearly related to the L/G ratio in the measuring interval. Turning off one of the lower spray levels, while burning coal with low S content, did not lower the overall removal efficiency of the absorber. However, the SO 2 gas phase concentration inside the lower part of the absorber was increased by a factor of 2–3. Measurements of slurry pH at different positions showed a decrease of approximately 0.5 units from the upper to the lower part of the absorber. The full-scale measurements provide a detailed set of experimental data for validation of mathematical models of a wet FGD spray absorber.