Coil resonator

Fig. 13.1 Photonic sensors that are either based on MNF sensing ((a),(b), (d), (e), (f)) or use MNF for the input and output connection (c), (g) (j). (a) straight MNF sensor with surrounding evanescent field (b) straight MNF sensor coated with bio or chemical layer and surrounding evanescent field (c) generic structure of MNF based optical sensor with surrounding evanescent field (d) straight MNF sensor (e) MNF loop resonator (MLR) sensor (f) MNF coil resonator (MCR) sensor (g) MNF/microsphere sensor (h) MNF/microdisk sensor (i) MNF/micro cylinder sensor (j) MNF/microcapillary sensor (k) a sensor composed of an MNF coupled to a series of microcylinders (optical fibers)...

Sumetsky, M., Basic elements for microfiber photonics micro/nanofibers and microfiber coil resonators, IEEE J. Lightwave Technol. 2008, 26, 21 27... 

Fei, X. Brambilla, G., Manufacture of 3 D microfiber coil resonators, IEEE Photon. Technol. Lett., 2007, 19, 1481 1483... 

Xu, F. Brambilla, G., Embedding optical microfiber coil resonators in Teflon, Opt. Lett. 2007, 32, 2164 2166... 

Xu, F. Horak, P. Brambilla, G., Optical microfiber coil resonator refractometric sensor, Opt. Express 2007, 15, 7888 7893... 

The transmitter power needs to be adjusted to provide pulses short enough to obtain nonselective 180° pulses. In applications requiring large coils, resonators can be constructed which are fed with the sine and the cosine component of the rf signal [Hou2]. By using such circularly polarized excitation a factor of two is saved in the rf power in comparison to linearly polarized excitation [Glol]. 

Xu F, Brambilla G (2008) Demonstration of a refractometric sensor based on optical microfiber coil resonator. Appl Phys Lett 92 101126... 

The absolute measurement of areas is not usually usefiil, because tlie sensitivity of the spectrometer depends on factors such as temperature, pulse length, amplifier settings and the exact tuning of the coil used to detect resonance. Peak intensities are also less usefiil, because linewidths vary, and because the resonance from a given chemical type of atom will often be split into a pattern called a multiplet. However, the relative overall areas of the peaks or multiplets still obey the simple rule given above, if appropriate conditions are met. Most samples have several chemically distinct types of (for example) hydrogen atoms within the molecules under study, so that a simple inspection of the number of peaks/multiplets and of their relative areas can help to identify the molecules, even in cases where no usefid infonnation is available from shifts or couplings. 

The heart of an NMR spectrometer is the probe, which is essentially a tuned resonant circuit with the sample contained within the main inductance (the NMR coil) of that circuit. Usually a parallel tuned circuit is used with a resonant frequency of coq = The resonant frequency is obviously the most important probe... 

With appropriate caUbration the complex characteristic impedance at each resonance frequency can be calculated and related to the complex shear modulus, G, of the solution. Extrapolations to 2ero concentration yield the intrinsic storage and loss moduH [G ] and [G"], respectively, which are molecular properties. In the viscosity range of 0.5-50 mPa-s, the instmment provides valuable experimental data on dilute solutions of random coil (291), branched (292), and rod-like (293) polymers. The upper limit for shearing frequency for the MLR is 800 H2. High frequency (20 to 500 K H2) viscoelastic properties can be measured with another instmment, the high frequency torsional rod apparatus (HFTRA) (294). 

From this equaiion one can determine the required value of neutral circuit impedance for a particular level of ground fault current. The external impedance will be Z, less the ground impedance. In HT systems one c in also delermine the likely value of a ground inductor coil to achieve a near-resonance condition, to eliminate the arcing grounds, on the one hand, and facilitate a strike-free extinction of an arc hy the interrupting device, on the other. 

In grids with resonant grounding, in the event of a current failure the residual ground fault current or the coil current, or parts thereof, can flow for several hours through the resistance. The coil current can be up to 400 A, depending on the size of the grid. Failure currents and voltages on cathodically protected pipes are described in detail in Ref. 8. 

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