PubMed · 8147320
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D Rylaarsdam, R Arzbaecher. 1994-03-15. Error in published article.. https://doi.org/10.1016/0002-9149(94)90354-9
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Three cell geometries, closed cubic, closed elongated, and open elongated, are evaluated for optimum remeasurement performance in the Fourier transform ion cyclotron resonance mass spectrometry (FTICR) experiment. The advantages and disadvantages of each cell during normal FTICR operation are discussed. Unit remeasurement efficiency is obtained for the closed elongated cell at approximately 71% of the cell radius, whereas the open elongated cell achieves unit remeasurement at only approximately 18% of the cell radius. The closed cubic cell does not achieve unit remeasurement efficiency at a detectable signal level. A correlation between remeasurement efficiency and the characteristic radial electric field of each trapped ion cell is established. Radial dispersion of the ion cloud is considered the dominant signal loss mechanism in the remeasurement experiment, and cell geometries are examined for optimized sensitivity and unit remeasurement efficiency.
We evaluated the electrical events and the resulting shock waves of the spark discharge for electrohydraulic lithotripsy at the tip of a 3.3F probe. Spark generation was achieved by variable combinations of voltage and capacity. The effective electrical output was determined by means of a high-voltage probe, a current coil, and a digital oscilloscope. Peak pressures, rise times, and pulse width of the pressure profiles were recorded using a polyvinylidene difluoride needle hydrophone in 0.9% NaCl solution at a distance of 10 mm. The peak pressure and the slope of the shock front depend solely on the voltage, while the pulse width was correlated with the capacity. Pulses of less than 1-microsecond duration can be obtained when low capacity is applied and the inductivity of the cables and plugs is kept at a low level. Using chalk as a stone model it was proven that short pulses of high peak pressure provided by a low capacity and a high voltage have a greater impact on fragmentation than the corresponding broader shock waves of lower peak pressure carrying the same energy.