摘要:

This paper reports the results of the operation, under active computer control, of a high‐voltage (400 kV) injector. The automation system uses a microcomputer placed on the high‐voltage deck of the ion source, which takes over some of the process control decisions, and a master IBM‐PC at ground potential. Various ion beams (p, H+2, H+3,d, He+, He2+) have been produced, proving the reliability of the system. A maximum value of 460 kV accelerating potential has been reached during the tests. The beam fulfills the requirements for the operation of a room‐temperature IH linac. By using a modular expandable computer system the acceleration voltage is continuously adjusted keeping its standard error within 0.1%. A future enlargement of the injector has been taken into account and the upgrading of the control system for an electron cyclotron resonance ion source would be very simple. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146564

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

A spin flipper of reliable and robust long‐term operation was developed and has been used successfully at the Indiana University Cooler Storage Ring. To reverse the polarization of the stored beam, the frequency of a rf solenoid is swept adiabatically across a depolarizing resonance frequency. Depolarizing sidebands to the resonance are eliminated by shorting out the ring’s bunching rf cavity prior to the frequency sweep. With the spin flipper it is no longer necessary to dump the stored beam and to refill the ring with protons of opposite spin state. Rather, beam accumulation continues without reversing the spin at injection, and instead the polarization of the stored beam is flipped periodically. Thus the luminosity is significantly increased when the flipper is used. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146565

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We have designed a multipulse laser system to measure nanosecond time scale, plasma‐density gradients by moire´ deflectometry. The complete system consists of four, transverse‐excited, atmospheric pressure (TEA) N2laser oscillators and two low‐pressure N2laser amplifiers; two oscillator pulses are injected into a single amplifier. The amplified pulses are less than 1 ns in duration, with a variable, interpulse time of 4–10 ns. As described here, two TEA oscillators and a single amplifier were used to image air‐density gradients in an expanding, air‐shock wave produced by a spark discharge. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146566

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

For the lifetime evaluation of plasma facing materials in fusion experimental machines, it is essential to investigate their surface behavior and their temperature responses during an off‐normal event such as the plasma disruptions. An infrared thermometer with a sampling speed as fast as 1×10−6s/data, namely, the high‐speed infrared thermometer (HSIR), has been developed by the National Research Laboratory of Metrology in Japan. To evaluate an applicability of the newly developed HSIR on the surface temperature measurement of plasma facing materials, high heat flux beam irradiation experiments have been performed with three different materials under the surface heat fluxes up to 170 MW/m2for 0.04 s in a hydrogen ion beam test facility at the Japan Atomic Energy Research Institute. As for the results, HSIR can be applicable for measuring the surface temperature responses of the armor tile materials with a little modification. It is also confirmed that surface temperatures measured with the HSIR thermometer show good agreement with the analytical results for stainless steel and carbon based materials at a temperature range of up to 2500 °C. However, for aluminum the HSIR could measure the temperature of the high dense vapor cloud which was produced during the heating due to lower melting temperature. Based on the result, a multichannel arrayed HSIR thermometer has been designed and fabricated. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146567

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

An easy to assemble and inexpensive plasma diagnostic system is presented. An electrical single probe and its vacuum and electrical isolation arrangement, integrated to an automatic positioner device, has been constructed and tested in plasma environments. This system provides a more precise estimation of the probe electrode position than others previously proposed in the literature. To control the probe electrode position an electronic circuit based in a microcontroller device is used. This automatic positioner avoids the troubles related to a manual operation. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146568

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We have developed a ray‐tracing program to calculate the imaging properties of ellipsoidal and toroidal mirrors in glancing angle configurations. It has been proposed that such mirrors be used in small angle neutron scattering instruments, in order to achieve increased count rates without sacrificing angular resolution. We describe the method of calculation, including effects due to gravity, and we present a number of instructive examples of calculations for both types of mirrors. We also illustrate a practical method of reducing image degradation associated with gravitational effects. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146569

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We have designed a gas gun capable of delivering a projectile on target within a time window of 60 &mgr;s, and up to velocities of 182 m/s. The gun uses a prepressurized brass projectile held in place with a glass rod in compression. The glass rod is fractured at a precise time using an explosive detonator. Performance calculations were conducted using a simplified model, and the predictions compare favorably with experimental data. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146570

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

A system for measurement of less than 1 ppt (parts per trillion) of helium contained in a solid within the range of mass between 100 mg and 1 g has been developed for the primary purpose of measuring neutron‐induced helium production cross sections. The system consists of an apparatus based on ultrahigh vacuum techniques, computer codes to estimate suitable parameters for the given experimental conditions and to control data acquisition parts, and an appropriate routine of operation of the system. The system apparatus consists of a gas releaser, a mass spectrometer, and a standard helium supply. A sample containing helium is evaporated in the gas releaser and the gas is analyzed with the mass spectrometer after purifying it for helium to decrease background gases. The background of helium for a dummy sample of silicon is measured to be 0.04 ppt. The total uncertainty of the apparatus is 4.4% in the range of (0.5–5.0)×1010He measurement. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146571

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The construction of the baffle system for the GAS instrument (neutral hydrogen analyzer) prepared for the RELICT‐2 space mission is presented. The method and the equipment used for the direct measurements of the baffle’s suppression factor of the ultraviolet photons flux (Ly‐&agr; spectral line) are described and the main physical parameters of the device are given. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146572

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Multiple‐stage seismic vibration isolation stacks, which consist of alternating layers of stiff masses and compliant springs, can provide significant passive filtering of ground vibration for experiments and equipment that are sensitive to mechanical noise. We describe the design, modeling and testing of a prototype of a stack suitable for use in the Laser Interferometer Gravitational‐wave Observatory (LIGO). This is a four‐stage elastomer (spring) and stainless steel (mass) stack, consisting of a table resting on three separate legs of three layers each. The viscoelastic properties of elastomer springs are exploited to damp the stack’s normal modes while providing rapid roll‐off of stack transmission above these modal frequencies. The stack’s transmission of base motion to top motion was measured in vacuum and compared with three‐dimensional finite‐element models. In one tested configuration, at 100 Hz, horizontal transmission was 10−7, vertical transmission was 3×10−6, and the cross‐coupling terms were between these values. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146573

出版商:AIP    

年代:1996

数据来源: AIP