摘要:

We describe the design of a type of millimeter wave antenna which is particularly suitable in plasma diagnostics applications. It is an all metal focussing hog‐horn antenna. Its main advantages are high spatial resolution, capability of working at short distance, little space taken, wide band, ruggedness. Moreover it does not produce vacuum or plasma bombardment problems.

ISSN:0034-6748    

DOI:10.1063/1.1136364

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A pulse‐counting mass spectrometer is described which is comprised of a new ion source of cylindrical geometry, with exceptional optical properties (the Baur source), a dual focal plane externally adjustable collector slits, and a 17‐stage Allen‐type electron multiplier, all housed in a metal 21 cm radius, 90° magnetic sector flight tube. Mass discrimination of the instrument is less than 1 per mil per mass unit; the optical transmission is more than 90%; the source sensitivity (Faraday collection) is 4 ma/torr at 250&mgr;m emission; and the abundance sensitivity is 3×104. A low blank extrction system is also described which routinely provides precedural blanks at 1600°C of approximately 10,000 atoms of132Xe. The corresponding blanks for84Kr,36Ar, and20Ne are 70,000, 4×106, and 5×107atoms respectively.

ISSN:0034-6748    

DOI:10.1063/1.1136365

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A film balance has been constructed that features a wide range (∼80 dynes/cm) and high sensitivity (∼10−3dyne/cm). The device is rugged, simple to operate and can be repeatedly assembled/disassembled in cycles (for cleanings) without affecting its mechanical parameters (nullpoint and sensitivity).

ISSN:0034-6748    

DOI:10.1063/1.1136366

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A method for the measurement of the dielectric constant parallel to a film surface is formulated. The distribution of electric charge and capacity were calculated as a function of the geometry of electrodes and the dielectric constant of the film. A concept of residual capacity was introduced to obtain the dielectric constant of the film from the observed capacity. Two sort of experiments was used to see if the method is sufficient in measurement of the dielectric constant parallel to film surface, and find the error in both cases was less than 10%. An example of the anisotropy of dielectric constant is shown in the case of a roll oriented nylon 12 film.

ISSN:0034-6748    

DOI:10.1063/1.1136367

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A simple method for the accurate determination of the quality factor,Q, of a reflection microwave cavity is described.

ISSN:0034-6748    

DOI:10.1063/1.1136368

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A low field magnet system is described which is suitable for optical and magnetic resonance experiments. It consists of three pairs of orthogonal Helmholtz coils, whose currents are controlled by a microcomputer to provide a magnetic field with a specific field and direction. Earth’s field compensation is programmed. The field magnitude is accurate to 0.1 G and direction to 0.3 deg for fields greater than 5 G. The maximum field is 50 G.

ISSN:0034-6748    

DOI:10.1063/1.1136369

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A parallel‐plate electrostatic aerosol size classifier has been constructed, analyzed, and tested. The instrument can produce sub‐micron aerosols with high output, good resolution in the size distribution, and of either single or mixed charge polarities. Performance tests were conducted on latex aerosols and on coal dust, and the instrument was used to calibrate a laser particle size analyzer on coal dust. Calculated and measured output sizes agree to about 7%. A size resolution of approximately 13% for monodisperse aerosols and 17% for a polydisperse coal dust aerosol was obtained.

ISSN:0034-6748    

DOI:10.1063/1.1136370

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

The presence of slowly varying signal drifts or low frequency (subharmonic) contributions can produce significant errors in the calculation of phase shifts using a correlation analysis. Under these conditions, the phase shift calculation becomes dependent on the reference signal phase angle. In this paper, we propose a modification to the correlation analysis to remove this dependency. We also present our analysis in discrete form to enable a digital implementation. Finally, we discuss the adverse effects that changes in the limits of integration can have on the phase shift calculation under the presence of linear signal drifts.

ISSN:0034-6748    

DOI:10.1063/1.1136371

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A technique is proposed which enables one to fabricate multi‐point field emission sources of bakeable structure. The technique is based on the cathodic growth of metallic needle crystal from metal crabonyl vapors and has so far been confirmed to provide emission sources of W, Mo, and Mo2C. The field emission sources prepared by this technique are highly resistive to thermal treatment and actually yield field ions possessing satisfactory intensities when used as the ion sources of a field ion mass spectrometer. It is believed that the application of these field emission sources is not restricted to mass spectrometry but can be extended to other ion and electron optical systems. The technique may thus open new areas in field emission technology.

ISSN:0034-6748    

DOI:10.1063/1.1136372

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

We describe a low voltage open loop control for high voltage capacitor charging circuits. The control is achieved by counting the number of halfcycles from the line supply that are allowed to excite the HV transformer primary. This number of half cycles determines the amount of charge stored in the capacitor, therby setting its voltage to the desired value. This open loop system avoids the use of HV sampling or switching. An implementation is presented for a RC charging circuit, together with graphs and formulas for design purposes. LC resonant charging is also discussed.

ISSN:0034-6748    

DOI:10.1063/1.1136382

出版商:AIP    

年代:1980

数据来源: AIP