Radiofrequency generators

Q. Explain the difference between a free-running and a crystal-controlled radiofrequency generator 4.4.3 Sample Introduction... 

A schematic diagram of an ICP-MS instrument is shown in Fig. 5.1. The TCP part bears an almost exact resemblance to the ICP used for atomic emission spectrometry, with the obvious exception that it is turned on one side. Indeed, sample introduction systems, radiofrequency generators and the nature of ICP itself are often the same for ICP-MS and ICP-AES systems, with the usual variations between individual manufacturers. 

A flow of argon in which ionisation has been initiated by a tesla discharge passes through an open quartz tube. A water-cooled copper tube is coiled around the quartz tube (Fig. 15.1). The copper tubing is connected to a radiofrequency generator (typically at 27 MHz) with a power of 1 to 2 kilowatts. The variable magnetic field that is created confines the ions and electrons to an annular path (with the appearance of an eddy current). As this environment becomes more and... 

The excitation source comprising the plasma torch, the induction coil connected to a radiofrequency generator and a nebuliser or system for sample introduction... 

Monomers were purchased from Polysciences, Inc. The liquid monomers (methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, methyl acrylate, n-butyl acrylate, methacrylic acid, acrylic acid, styrene and a-methylstyrene) were purified by vacuum distillation under nitrogen, poured into thin-walled ampules, degassed at 10 - 10 torr and subsequently frozen in liquid nitrogen. The partially filled ampules were then inserted between a pair of parallel plate electrodes connected to an International Plasma Corporation Model 3001 Radiofrequency Generator, which operates at 13.56 MHz and delivers up to 150 watts of power. In most of these experiments discussed in this work, the power input was limited to 40 - 80 watts. The ampules were allowed to warm up until droplets of liquids appeared. A glow discharge was then in-Current address Department of Chemistry, Ibaraki, University, Mito 310 Japan... 

To initiate the plasma, a flow of argon, weakly ionized by sparks (Tesla discharge), passes through an open quartz tube situated on the axis of several turns of a water-cooled copper tubing (Figure 14.3). This conductive coil is connected to a radiofrequency generator (typically 40.68 MHz and with a power of 1-2 kW). 

The main elements of an NMR spectrometer are depicted in Fig. 9.20. There are four basic components the magnet, the probe, the system of radiofrequency generation and detection, and the recording and computing system. 

The essential elements of an NMR spectrometer are a powerful magnet, a radiofrequency generator, a radio-frequency detector, and a sample tube (Figure 13.4). 

Radiofrequency generator (Tasanm Ltd. Co.-Turkey, frequency 13.6 MHz and power range 0-100 W) was used to form the plasma in the reactor. Power losses were kept to a minimum by a matching network. 

The radiofrequency generator is then activated at a power output of A80 W. This value was obtained by measuring the voltage across the coil and the current between the blocking and tank capacitors. 

Oshiro T, Sinha U, Lu D, et al (2002) Reduction of electronic noise from radiofrequency generator during radiofrequency ablation in interventional MRI. J Comput Assist Tomogr 26 308-316... 

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