摘要:

A pulsed marginal oscillator has been developed for use in pulsed ion cyclotron resonance experiments. The circuit performs quite well as a means of detecting gaseous ions in a magnetic field when the cyclotron frequency of the ions is equal to the resonant frequency of the oscillator. A pulsed marginal oscillator is different from previous marginal oscillator designs in that a gated amplifier is incorporated in the feedback loop for pulsing the oscillator on and off. This feature is important for delayed detection of ions which are formed as a result of chemical reactions in the gas phase. Oscillation levels from 2 to 500 mV (p‐p) are obtained over a frequency range fram 50 kHz to 2 MHz.

ISSN:0034-6748    

DOI:10.1063/1.1686304

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

A pulsed NMR system for platinum nuclear spin thermometry and for measurements of the nuclear spin‐lattice relaxation time &tgr;1has been developed. The nuclear free precession signal is detected with a fast linear detector and anRCintegrator. The &tgr;1measurements were performed by the transient recovery method with the aid of automated circuitry multiplexing of the linear detector output into four separate integrators. The thermometer was tested between 10 mK and 2 K using a powdered platinum sample. Within the experimental accuracy of about 2% the amplitude of the nuclear free precession signal was found to be proportional to 1/T. The thermometer could be calibrated with the aid of the Korringa relation &tgr;1T=&kgr;, with &kgr;=29.6 msec K. Thermal equilibrium problems of the &tgr;1measurements are discussed in detail.

ISSN:0034-6748    

DOI:10.1063/1.1686305

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Birefringence studies on conducting solutions are not easily performed for several experimental reasons; these difficulties are discussed. An apparatus which allows Kerr effect experiments on high ionic strength solutions is described. It is built around a fast high‐power switching device, which generates the electric pulse. Rectangular pulses of 30 kV can be applied to weakly conducting solutions (<10−2MNaCl). For a 0.1MNaCl solution, the amplitude still reaches 15 kV. In any case, the 10%–90% rise and decay time is about 50 nsec. The pulse amplitude and duration are adjustable in large limits. This pulse generator can also be used to apply reversing pulses or sinusoi¨dal wave bursts. It is possible with this apparatus to measure the electric birefringence of urea, for instance, in high ionic strength solvents (NaCl 0.1M).

ISSN:0034-6748    

DOI:10.1063/1.1686306

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

A field theory of bimodal cavity spin inductors for ERP spectrometry is developed. All the leakage effects are taken into account in order to attain results which are useful for an optimum design of such devices. Furthermore, perturbations of the cavity shape are considered in order to study the behavior of external decoupling devices. A general equivalent network is derived and formulas are given to evaluate all its parameters for any particular case. All the requirements to be fulfilled in order to minimize leakage and its frequency dependence are discussed. The general results obtained can be useful for the designer, who will be able to quantitatively evaluate the characteristic of a particular resonator, to compare different solutions, and to optimize all the parameters involved in a particular design.

ISSN:0034-6748    

DOI:10.1063/1.1686307

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

A computer program has been developed for accurately and rapidly determining the Miller indices for any number of Laue diffraction spots for a crystal of any symmetry and with arbitrary orientation relative to the x‐ray beam. Using thexycoordinates of each Laue spot the program goes directly to the assignment and verification of the Miller indices without the necessity of using nets and measuring angles.

ISSN:0034-6748    

DOI:10.1063/1.1686308

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

An improved FEM for probe hole measurements and a convenient method for the evaluation of probe hole data have been developed during studies of coadsorption of oxygen on tungsten and oxygen and/or cesium on molybdenum. The entire emission pattern is accessible thereby for the investigation of adsorption parameters. An arbitrary plane can be chosen for examination by means of a manipulator. The changes in the field emission current during adsorption processes are recorded as a function of time. From these plots the corresponding changes in work function are derived by a special evaluation method. Time required for measuring and evaluating FEM data is considerably reduced and an improvement in accuracy is achieved as compared to the conventional method of drawing FN plots. The FEM, the method of evaluation, and some characteristic data obtained by this technique are presented.

ISSN:0034-6748    

DOI:10.1063/1.1686309

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Following a recent communication, deflection mapping studies have been made on a heated wire grid, the wake of a reacting drop, and a bat's wing flame. The compensator fringes have been used either as virtual inclined slits or for tracing back the deflected rays. The sensitiveness of the device has been discussed in either case and the corresponding utilities have been pointed out.

ISSN:0034-6748    

DOI:10.1063/1.1686310

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

An improved microwave power source for electrodeless discharge lamps is described. Stabilization of the integrated visible light output is achieved, rather than mere regulation of the magnetron current. A new controllable modulator system is given, which allows all modes from cw to variable level pulse modulation to be applied to the microwave power fed to the discharge lamp. Some observations on the characteristics of certain electrodeless lamps are discussed briefly.

ISSN:0034-6748    

DOI:10.1063/1.1686311

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

An experimental arrangement able to support crystal specimens for longitudinal electro‐optic measurements at temperatures up to 180°C is described. It allows for rapid and accurate alignment of crystallographic axes with respect to a polarized light beam, while also providing for some adjustment of the crystal at experimental temperature.

ISSN:0034-6748    

DOI:10.1063/1.1686312

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Descriptions are given of two circuits which generate scaler gating pulses and beam modulating pulses as required for crossed atomic beam experiments. For the case when only one of the crossed beams is modulated, a circuit is described in which a sinusoidal‐type signal is filtered by a tuned amplifier whose gain is 2000 and Q value is 260, and then passes through a level crossing detector, a frequency doubler, and several variable delays to produce two complementary square wave pulses. When both atomic beams are modulated, a second circuit produces a scaler gating pulse from each of the quadrants of the modulating period. Several combinations of variable delays permit variable phase differences between each of the four gating pulses. Circuit stability is better than 0.01%.

ISSN:0034-6748    

DOI:10.1063/1.1686313

出版商:AIP    

年代:1973

数据来源: AIP