摘要:

Synthetic cesium aluminosilicates in the form of &bgr;‐eucryptite (Cs2O⋅Al2O3⋅2SiO2) and spodumene (Cs2O⋅Al2O3⋅4SiO2) were used to construct thermionic emitters of Cs+ions. Total ion emission current and purity of ion emission of Cs+ions for these two forms of aluminosilicates were studied and compared at four different material surface temperatures over 50 h of continuous heating. In addition, the ion emission characteristics were investigated for three other compositions of cesium aluminosilicates. It was revealed that as a Cs+ion source, &bgr;‐eucryptite gives the optimum ion emission at the temperature of 1100 °C. ©1994 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1144498

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

Thrust vector stability for an electrostatic ion engine can be measured with improved sensitivity and time resolution by the method described here. Four double‐wire Langmuir probes, aligned in the form of a cross, are placed in the exhaust plume and are translated by a motorized positioning system to balance the currents collected along two orthogonal axes. The thrust vector position is thereby measured with an angular resolution of <0.01° and a response time of <5 s. ©1994 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1144499

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

Energy spread and extracted current measurements are presented for five different types of ion sources: hot cathode, cold cathode, magnetron, microwave, and electron cyclotron resonance (ECR). The measurements were performed with a 45° parallel‐plate energy analyzer with a resolution of better than 0.5 eV at 500 eV incident energy. Energy spreads ranged from 0.5 to 4 eV, while total extracted beam currents ranged from 2 to 30 &mgr;A. Beam currents due specifically to protons,3He++ions, and H+2ions are also presented. The ECR and magnetron sources gave the best overall performance. These, along with the energy analyzer, are currently being used in experiments to study ion‐atom collision physics. ©1994 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1144500

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

The design of a novel‐type of atomic beam source which provides for long term, stable operation at high emission rates is reported. The heart of the design is the ‘‘candlestick’’ where liquid source material is transported by capillary action to a localized hot emission region. A surrounding cavity kept at the melting point for the source material shields the vacuum chamber walls from this region. The atomic beam escaping from the source is collimated, and uncollimated atoms are transported back to the liquid reservoir at the bottom of the ‘‘candlestick’’ by capillary action. This design has advantages over traditional oven designs: localized heating provides for large emission rates under high vacuum conditions, collimation is combined with recycling and conservation of source material, and the use of capillarity allows any orientation of the beam source. The source has been tested with sodium, and we believe that the design is useful for a broad range of applications including thin‐film evaporation, molecular beam epitaxy, and semiconductor surface doping. With the low thermal mass of the emission section, the source could be optimized for pulsed mode operation. Furthermore, it is anticipated that the design ideas presented here could form the basis for a supersonic source with very high Mach numbers. ©1994 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1145246

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

An electron cyclotron resonance plasma source is built by arranging SmCo magnets to form a multicusp magnetic field with axial magnetic plugging. The source is tested in H2, N2, and Ar by the microwave of 2.45 GHz in the range from 10−2to 10−3Pa. The discharge sustaining power is measured as a function of pressure. The plasma density, the average electron energy, and the electron energy distribution are measured by using a Langmuir probe. Plasma is obtained at pressures as low as 10−3Pa in Ar. The average electron energy and the ion density increase with the feed microwave power. The electron energy distribution shows depletion at the low‐energy part. Ion spectra obtained in Ar show a multicharged state up to Ar8+. ©1994 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1144501

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

This article describes a Crossatron‐based modulator for driving 10–1000 &mgr;s duration plasma discharges. The modulator has demonstrated burst mode operation at pulse repetition rates of 50 kHz. Insulated gate bipolar transistors (IGBTs) are used to trigger the Crossatron. The pulse width of each individual pulse in a burst can be varied over a large range. A Jorway 221 timing and sequencing module command triggers the modulator, and a Labview‐based program is used to control the timing module via a GPIB bus. The modulator can output 25 kV pulses at 100 A. It can also operate at 10% duty cycle with peak currents of 10–20 A. ©1994 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1144502

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

A compact Bragg spectrometer for monochromatic imaging in the soft x‐ray region was designed and examined. With this spectrometer, a pinhole image is simultaneously recorded with a monochromatic image. This makes it possible to easily identify the wavelength when the location of the soft x‐ray source fluctuates from shot to shot, such as in the plasma focus andZ‐pinch plasma. An rubidium acid phtalate (RAP) flat crystal was examined and monochromatic images of the argonKlines around 4 A˚ were successfully obtained and displayed. The resolution power and dispersion obtained in situ were compared with the calculated values. ©1994 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1144503

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

A new optical data storage technology based on the surface‐enhanced Raman scattering (SERS) effect has been developed for high‐density optical memory and three‐dimensional data storage. With the surface‐enhanced Raman optical data storage (SERODS) technology, the molecular interactions between the optical layer molecules and the substrate are modified by the writing laser, changing their SERS properties, so that they are encoded to store information as bits. Since the SERS properties are extremely sensitive to molecular microenvironments, very small ‘‘spectrochemical holes’’ approaching the diffraction limit can be produced for the writing process. The SERODS device uses a reading laser to induce the SERS emission of molecules on the disk and a photometric detector tuned to the frequency of the Raman spectrum to retrieve the stored information. The results illustrate that SERODS is capable of three‐dimensional data storage. ©1994 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1144504

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

We analyze the experimental conditions required for the action of thermal, seismic, and excess noises on the test mass in the advanced LIGO experiment to be smaller than the uncertainty of the coordinate corresponding to the standard quantum limit. It is shown that the contribution of thermal noise can be made small enough if existing low‐dissipation materials are used for the suspension. On the other hand, the contribution of excess noise can be large and has to be examined thoroughly. ©1994 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1144505

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

A pendulum using four suspension wires in an X formation is described which can provide an arbitrarily long period in one dimension. Design equations are derived, and tested experimentally. A number of applications are outlined, including a low‐frequency vibration isolation system for a laser‐interferometric gravity wave observatory. ©1994 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1144506

出版商:AIP    

年代:1994

数据来源: AIP