摘要:

A technique using the focusing properties of a nonuniform axially symmetric magnetic field to study large angle (&thgr;>32°, lab) scattering of ions from atoms and molecules is described. The scattering cell is placed on the magnetic axis at the position of maximum field and ions in the momentum interval |&Dgr;p| at |p| scattered into a conical shell &Dgr;&thgr; at &thgr; are counted by a detector placed down along the axis in a region of low field. The solid angle is increased by a factor of several hundred over conventional scattering techniques of comparable angular resolution due to the azimuthal symmetry of the apparatus. The magnetic vector potential and the trajectory equation for a charged particle in this type of inhomogeneous, axially symmetric field are derived. As a preliminary test the known differential scattering cross section for He+on the He was measured from 40 to 52° (lab) at 300 eV. Results of measurements of the absolute differential scattering cross sections for Li+on He from 36 to 41.7° at 200 and 300 eV, corresponding to CM scattering angles of 90 to 160°, are presented.

ISSN:0034-6748    

DOI:10.1063/1.1683855

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

An optical method for the simultaneous determination of species concentration and temperature in a high pressure transient combustion and expansion process is described. The experimental system utilizes a mechanically chopped (2000 Hz) external radiation signal to perturb the self‐emission signal from the combustion gas of an internal combustion engine. Distinguishing between the emission and absorption signals simultaneously provides a capability for determination of species concentration by absorption and of optical temperature by an emission‐absorption technique.

ISSN:0034-6748    

DOI:10.1063/1.1683857

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

Spherical multipole (SM) magnetic fields are used for plasma containment. Such magnetic fields are produced by magnetic dipoles symmetrically placed on the sides and the edges of regular polyhedrons. In the paper, field configuration of the high order SM systems is considered and some basic problems regarding the design of SM electromagnets are discussed. Relations are given relating magnetic field, power input, current‐ and temperature‐ time characteristics. The construction and operation of the ``Kaktus'' magnet are also described.

ISSN:0034-6748    

DOI:10.1063/1.1683858

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

The operation of an assembly using a uniform resistive surface to provide deflection of an electron beam is discussed. Essentially, the assembly consists of electroded plates of doped lead glass fused together and fired in hydrogen to produce the continuous resistive surface. Results indicate that when this assembly is employed in an image dissector tube, a 30° deflection can be obtained on either side of the central axis. The assembly was also operated with a vidicon gun and a test pattern was reproduced with very little distortion.

ISSN:0034-6748    

DOI:10.1063/1.1683859

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

An ionization gauge is described which uses an ion gun designed for end extraction. An out‐of‐sight ion collector is used to extend the x‐ray limit normally present in simpler structures. The gauge head has a sensitivity of 60 Torr−1without a secondary suppressor electrode or 20 Torr−1with a secondary suppressor. The gauge head is not difficult to make, uses a simple power supply, and does not require any focusing adjustment. Ion trajectories, plotted by a digital computer, are used to give an insight into the efficient operation of the structure.

ISSN:0034-6748    

DOI:10.1063/1.1683860

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

A new type of gas fed hollow cathode (multichannel cathode) has been studied. Such cathodes operate with a lower voltage drop and higher maximum current density than conventional one‐channel cathodes and have a longer lifetime as well. Moreover, multichannel cathodes allow operation within a wide range of discharge currents and with extremely low gas flow rates. A theoretical analysis clarifies the principles of the operation of this type of cathode. The experimental results are explained and some general rules are presented for the cathode design.

ISSN:0034-6748    

DOI:10.1063/1.1683861

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

The temperature dependence of the thermal conductivity of silicone vacuum grease, Cry‐Con grease (a copper loaded electrically insulating grease), and Eccotherm TC‐4 (a specially formulated paste based on silicones and fillers) has been measured at liquid helium temperatures. It is concluded that the (thermal) greases examined have thermal conductivities in bulk corresponding approximately to those of thermal insulators. The successful use of thermal bonding greases to effect heat transfer at liquid helium temperatures and below requires very thin layers of the greases, in order to avoid the deleterious effect of their poor thermal conductivity in bulk.

ISSN:0034-6748    

DOI:10.1063/1.1683862

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

A mixture of 5% O2in He has been used in a rf discharge at pressures from 15 to 70 Torr to produce a free jet source of a high intensity energetic beam of atomic oxygen. Intensities of 1017atoms/sec/sr are predicted and energies of 0.33 eV have been measured. A time‐of‐flight analysis of the beam properties is presented and indicates that the source temperature is near 620 K.

ISSN:0034-6748    

DOI:10.1063/1.1683863

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

A laser interferometer for the study of earth strain is described. Changes in the length of an 800 m arm are measured by counting fringes in the interference pattern with a least count of 4×10−10. The output is linear and has a flat response from dc to 1 MHz and a dynamic range of 106. The laser wavelength is controlled by reference to a passive optic resonator contained in a stable environment. The wavelength stability is a few parts in 1010for periods up to a laser lifetime (∼3000 h).

ISSN:0034-6748    

DOI:10.1063/1.1683864

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

The ionization coefficient of a potassium atom impinging on a hot Pt‐8% W wire is independent of its energy below 3 eV (3850 m/sec) and dependent on it above 3 eV. This is due to the fact that a high energy atom can reflect from the wire without being ionized. By using a tungsten cylinder as an ionizer and a niobium wire in the middle of it as a collector, incident atoms which are not ionized can be prevented from leaving the cylinder without being detected because subsequent collisions with the wall will take place and result in ionization. By means of this type of standard detector, which has a multiplication factor of about 30, the reflection coefficient of a potassium atom incident on a Pt‐8% W wire is determined as a function of its velocity. For a potassium atom with an energy of 23.6 eV (10 800 m/sec) this reflection coefficient is about 16.5%.

ISSN:0034-6748    

DOI:10.1063/1.1683865

出版商:AIP    

年代:1969

数据来源: AIP