Design of a continuous duty cryopump (open access)

Design of a continuous duty cryopump

A continuous duty cryopump system was designed and developed that comprises a self-contained cryopump for installation into a vacuum chamber, and a microprocessor controller for automatic operation. This deuterium pump has two units in a single housing, arranged so that one is pumping while the other is being regenerated. Liquid helium-cooled, finned sections in each unit pump deuterium by condensation, and a third pump integral within the cryopump housing collects the regenerated gas. A microprocessor unit controls distribution of liquid and gaseous helium, used for conditioning the pumping units, and operates remote actuators for the regeneration. Software provides fully automatic, timed sequencing of the repetitive cryopump events which include: cooldown of the pumping units, opening of the louvers isolating the unit from the vacuum chamber, closing of the louvers, and warming up of the unit for regeneration. Default values in the software can be reprogrammed by the operator through the keyboard in response to prompts displayed on the computer. An override allows the operator to control the cryopump manually by activating switches on a control panel. Interlocks to prevent cryogen lockup are included in the software.
Date: May 1, 1985
Creator: Sedgley, D.W.
Object Type: Report
System: The UNT Digital Library
Evaluation of the gas production economics of the gas hydrate cyclic thermal injection model. [Cyclic thermal injection] (open access)

Evaluation of the gas production economics of the gas hydrate cyclic thermal injection model. [Cyclic thermal injection]

The objective of the work performed under this directive is to assess whether gas hydrates could potentially be technically and economically recoverable. The technical potential and economics of recovering gas from a representative hydrate reservoir will be established using the cyclic thermal injection model, HYDMOD, appropriately modified for this effort, integrated with economics model for gas production on the North Slope of Alaska, and in the deep offshore Atlantic. The results from this effort are presented in this document. In Section 1, the engineering cost and financial analysis model used in performing the economic analysis of gas production from hydrates -- the Hydrates Gas Economics Model (HGEM) -- is described. Section 2 contains a users guide for HGEM. In Section 3, a preliminary economic assessment of the gas production economics of the gas hydrate cyclic thermal injection model is presented. Section 4 contains a summary critique of existing hydrate gas recovery models. Finally, Section 5 summarizes the model modification made to HYDMOD, the cyclic thermal injection model for hydrate gas recovery, in order to perform this analysis.
Date: May 1, 1985
Creator: Kuuskraa, V.A.; Hammersheimb, E. & Sawyer, W.
Object Type: Report
System: The UNT Digital Library
Control of indoor radon and radon progeny concentrations (open access)

Control of indoor radon and radon progeny concentrations

There are three general categories of techniques for the control of radon and radon progeny concentrations in indoor air - restriction of radon entry, reduction of indoor radon concentrations by ventilation or air cleaning, and removal of airborne radon progeny. The predominant radon entry process in most residences appears to be pressure driven flow of soil gas through cracks or other openings in the basement, slab, or subfloor. Sealing these openings or ventilation of the subslab or subfloor space are methods of reducing radon entry rates. Indoor radon concentrations may be reduced by increased ventilation. The use of charcoal filters for removal of radon gas in the indoor air by adsorption has also been proposed. Concentrations of radon progeny, which are responsible for most of the health risks associated with radon exposures, can be controlled by use of electrostatic or mechanical filtration. Air circulation can also reduce radon progeny concentrations in certain cases. This paper reviews the application and limitations of each of these control measures and discusses recent experimental results.
Date: May 1, 1985
Creator: Sextro, R.G.
Object Type: Article
System: The UNT Digital Library
New rf power system for SuperHILAC (open access)

New rf power system for SuperHILAC

The upgraded rf system for the SuperHILAC is now operational using 9 new tetrode amplifiers. Each amplifier can produce in excess of 1MW of 70 Mhz pulsed rf power. Ferrite is used to decouple the screen grid circuit and to absorb parasitic oscillations. This results in a very stable amplifier with reasonable gain. This system uses a common 8 MW anode power supply and crowbar system. Overall system efficiency has been increased significantly. We project a 3 year payback on the equipment cost, realized from the power savings alone. 2 refs., 5 figs.
Date: May 1, 1985
Creator: Fugitt, J.; Lancaster, H. & Sorensen, R.
Object Type: Article
System: The UNT Digital Library
Application of a dc SQUID to rf Amplification: NQR (open access)

Application of a dc SQUID to rf Amplification: NQR

Superconducting QUantum Interference Devices (SQUIDs) have been used for more than a decade for the detection of magnetic resonance. Until recently, these devices had mostly been confined to operation in the audiofrequency range, so that experiments have been restricted to measurements of resonance at low frequencies, or of changes in the static susceptibility of a sample induced by rf irradiation at the resonant frequency. However, the recent extension of the operating range of low noise dc SQUIDs to radiofrequencies (rf) allows one to detect magnetic resonance directly at frequencies up to several hundred megahertz. In this paper, we begin by summarizing the properties of dc SQUIDs as tuned rf amplifers. We then describe first, the development of a SQUID system for the detection of pulsed nuclear quadrupole resonance (NQR) at about 30 MHz and second, a novel technique for observing magnetic resonances in the absence of any externally applied rf fields.
Date: May 1, 1985
Creator: Hilbert, C.; Clarke, J.; Sleator, T. & Hahn, E. L.
Object Type: Article
System: The UNT Digital Library
Analytical methods of electrode design for a relativistic electron gun (open access)

Analytical methods of electrode design for a relativistic electron gun

The standard paraxial ray equation method for the design of electrodes for an electrostatically focused gun is extended to include relativistic effects and the effects of the beam's azimuthal magnetic field. Solutions for parallel and converging beams are obtained and the predicted currents are compared against those measured on the High Brightness Test Stand. 4 refs., 2 figs.
Date: May 9, 1985
Creator: Caporaso, G.J.; Cole, A.G. & Boyd, J.K.
Object Type: Article
System: The UNT Digital Library
High-spin properties of some nuclei around A = 160 (open access)

High-spin properties of some nuclei around A = 160

Two new types of behavior have been observed in /sup 156/Er. The first is a terminating band ending on a 42+ fully aligned state. The second is a strong cross feeding among four negative parity bands, due most likely to a severe reduction or collapse of the neutron pairing. In /sup 158/Er we have found two sequences feeding the 38+ level; one slow and one fast. This suggests that some feeding goes through regions of oblate (or nearly so) shapes, and some does not. Lifetimes have been determined for levels around 30+ in /sup 166/Yb, which seem to be longer than is easily explained. 23 refs, 8 figs.
Date: May 1, 1985
Creator: Stephens, F.S.
Object Type: Article
System: The UNT Digital Library
Macroscopic quantum effects in the zero voltage state of the current biased Josephson junction (open access)

Macroscopic quantum effects in the zero voltage state of the current biased Josephson junction

When a weak microwave current is applied to a current-biased Josephson tunnel junction in the thermal limit the escape rate from the zero voltage state is enhanced when the microwave frequency is near the plasma frequency of the junction. The resonance curve is markedly asymmetric because of the anharmonic properties of the potential well: this behavior is well explained by a computer simulation using a resistively shunted junction model. This phenomenon of resonant activation enables one to make in situ measurements of the capacitance and resistance shunting the junction, including contributions from the complex impedance presented by the current leads. For the relatively large area junctions studied in these experiments, the external capacitive loading was relatively unimportant, but the damping was entirely dominated by the external resistance.
Date: May 1, 1985
Creator: Clarke, J.; Devoret, M. H.; Martinis, J. & Esteve, D.
Object Type: Article
System: The UNT Digital Library
CBEAM. 2-D: a two-dimensional beam field code (open access)

CBEAM. 2-D: a two-dimensional beam field code

CBEAM.2-D is a two-dimensional solution of Maxwell's equations for the case of an electron beam propagating through an air medium. Solutions are performed in the beam-retarded time frame. Conductivity is calculated self-consistently with field equations, allowing sophisticated dependence of plasma parameters to be handled. A unique feature of the code is that it is implemented on an IBM PC microcomputer in the BASIC language. Consequently, it should be available to a wide audience.
Date: May 1, 1985
Creator: Dreyer, K. A.
Object Type: Report
System: The UNT Digital Library
Experimental operation of a sodium heat pipe (open access)

Experimental operation of a sodium heat pipe

This report documents the operation of a 28 in. long sodium heat pipe in the Heat Pipe Test Facility (HPTF) installed at Argonne National Laboratory. Experimental data were collected to simulate conditions prototypic of both a fluidized bed coal combustor application and a space environment application. Both sets of experiment data show good agreement with the heat pipe analytical model. The heat transfer performance of the heat pipe proved reliable over a substantial period of operation and over much thermal cycling. Additional testing of longer heat pipes under controlled laboratory conditions will be necessary to determine performance limitations and to complete the design code validation. 2 refs., 23 figs., 2 tabs.
Date: May 1, 1985
Creator: Holtz, R.E.; McLennan, G.A. & Koehl, E.R.
Object Type: Report
System: The UNT Digital Library
Numerical simulation of an accelerator injector (open access)

Numerical simulation of an accelerator injector

Accelerator injector designs have been evaluated using two computer codes. The first code self consistently follows relativistic particles in two dimensions. Fields are obtained in the Darwin model which includes inductive effects. This code is used to study cathode emission and acceleration to full injector voltage. The second code transports a fixed segment of a beam along the remainder of the beam line. Using these two codes the effects of electrode configuration on emittance, beam quality and beam transport have been studied.
Date: May 9, 1985
Creator: Boyd, J.K.; Caporaso, G.J. & Cole, A.G.
Object Type: Article
System: The UNT Digital Library
Initial measurements of beam breakup instability in the advanced test accelerator (open access)

Initial measurements of beam breakup instability in the advanced test accelerator

This paper reports the measurements of beam breakup (BBU) instability performed on the Advanced Test Accelerator (ATA) up to the end of February, 1984. The main objective was to produce a high current usable electron beam at the ATA output. A well-known instability is BBU which arises from the accelerator cavity modes interacting with the electron beam. The dominant mode is TM/sub 130/ at a frequency of approximately 785 MHz. It couples most strongly to the beam motion and has been observed to grow in the Experimental Test Accelerator (ETA) which has only eight accelerator cavities. ATA has one hundred and seventy cavities and, therefore, the growth of BBU is expected to be more severe. In this paper, BBU measurements are reported for ATA with beam currents of 4 to 7 kA. Analysis showed that the growth of the instability with propagation distance was as expected for the lower currents. However, the high-current data showed an apparent higher growth rate than expected. An explanation for this anomaly is given in terms of a ''corkscrew'' excitation. The injector BBU noise level for a field emission brush cathode was found to be an order of magnitude lower than for a cold plasma …
Date: May 13, 1985
Creator: Chong, Y.P.; Caporaso, G.J. & Struve, K.W.
Object Type: Article
System: The UNT Digital Library
Calculational tools for the evaluation of nuclear cross-section and spectra data (open access)

Calculational tools for the evaluation of nuclear cross-section and spectra data

A technique based on discrete energy levels rather than energy level densities is presented for nuclear reaction calculations. The validity of the technique is demonstrated via theoretical and experimental agreement for cross sections, isomer-ratios and gamma-ray strength functions. 50 refs., 7 figs. (WRF)
Date: May 7, 1985
Creator: Gardner, M.A.
Object Type: Article
System: The UNT Digital Library
Characterization of acoustic emission signals generated by water flow through intergranular stress corrosion cracks (open access)

Characterization of acoustic emission signals generated by water flow through intergranular stress corrosion cracks

A program is under way at Argonne National Laboratory (ANL) to develop an independent capability to assess the effectiveness of current and proposed techniques for acoustic leak detection (ALD) in reactor coolant systems. The program will establish whether meaningful quantitative data on flow rates and leak location can be obtained from acoustic signatures of leaks due to intergranular stress corrosion cracks (TGSCCs) and fatigue cracks, and whether these can be distinguished from other types of leaks. 5 refs., 3 figs.
Date: May 1, 1985
Creator: Claytor, T.N. & Kupperman, D.S.
Object Type: Article
System: The UNT Digital Library
Recent progress of the advanced test accelerator (open access)

Recent progress of the advanced test accelerator

Attempts to further improve the beam brightness from field emission cathodes are currently centered on the issue of how beam optics and phase mixing within the injector transport tend to ''average down'' the beam brightness. Particle simulation work indicates that beam brightness can be significantly improved by simply reducing the injector transport magnetic field and losing peak transport current, i.e., only transporting that high brightness portion of the total current. The simulation results shown in Figure 8 suggest that beam brightness can be increased perhaps a factor of 5 or more simply by ''tuning for brightness'' rather than tuning for peak transported current. If this can indeed be experimentally realized and the resulting beam matched onto accelerator transport (magnetic and/or laser guided) without emittance degradation then simple field emission cathodes would, at least in the immediately near term, saisfy the needs for 10 micron FEL experiments. 8 refs., 8 figs.
Date: May 13, 1985
Creator: Prono, D.S.
Object Type: Article
System: The UNT Digital Library
TRU waste lead organization -- WIPP Project Office Interface Management semi-annual report (open access)

TRU waste lead organization -- WIPP Project Office Interface Management semi-annual report

The Charter establishing the Interface Control Board and the administrative organization to manage the interface of the TRU Waste Lead Organization and the WIPP Project Office also requires preparation of a summary report describing significant interface activities.'' This report includes a discussion of Interface Working Group (IWG) recommendations and resolutions considered and implemented'' over the reporting period October 1984 to March 1985.
Date: May 1, 1985
Creator: Guerrero, J.V. & Gorton, J.M. (Rockwell International Corp., Albuquerque, NM (United States). Joint Integration Office)
Object Type: Report
System: The UNT Digital Library
Investigation of Re-X glass ceramic for acceleration insulating columns (open access)

Investigation of Re-X glass ceramic for acceleration insulating columns

In an induction linac the accelerating voltage appears along a voltage-graded vacuum insulator column which is a performance limiting and major cost component. Re-X glass ceramic insulators have the long-sought properties of allowing cast-in gradient electrodes, good breakdown characteristics, and compatibility with high vacuum systems. Re-X is a glass ceramic developed by General Electric for use in the manufacture of electrical apparatus, such as vacuum arc interrupters. We have examined vacuum outgassing behavior and voltage breakdown in vacuum and find excellent performance. The housings are in the shape of tubes with type 430 stainless steel terminations. Due to a matched coefficient of thermal expansion between metal and insulator, no vacuum leaks have resulted from any welding operation. The components should be relatively inexpensive to manufacture in large sizes and appear to be a very attractive accelerator column. We are planning to use a standard GE housing in our MBE-4 induction linac.
Date: May 1, 1985
Creator: Faltens, A. & Rosenblum, S.
Object Type: Article
System: The UNT Digital Library
High current beam transport with multiple beam arrays (open access)

High current beam transport with multiple beam arrays

Highlights of recent experimental and theoretical research progress on the high current beam transport of single and multiple beams by the Heavy Ion Fusion Accelerator Research (HIFAR) group at the Lawrence Berkeley Laboratory (LBL) are presented. In the single beam transport experiment (SBTE), stability boundaries and the emittance growth of a space charge dominated beam in a long quadrupole transport channel were measured and compared with theory and computer simulations. Also, a multiple beam ion induction linac (MBE-4) is being constructed at LBL which will permit study of multiple beam transport arrays, and acceleration and bunch length compression of individually focused beamlets. Various design considerations of MBE-4 regarding scaling laws, nonlinear effects, misalignments, and transverse and longitudinal space charge effects are summarized. Some aspects of longitudinal beam dynamics including schemes to generate the accelerating voltage waveforms and to amplify beam current are also discussed.
Date: May 1, 1985
Creator: Kim, C.H.
Object Type: Article
System: The UNT Digital Library
Lattice and bypass design for a coherent xuv facility (open access)

Lattice and bypass design for a coherent xuv facility

The design of a magnet lattice and bypass for a coherent radiation facility is discussed. The lattice is the missing magnet FODO structure first proposed by Vignola for a 6 GeV light source. This has been adapted for a 750-1300 MeV electron storage ring for use with both conventional insertion devices and a high gain FEL optimized for output at 400 A. The latter device requires that the electron bunch be deflected into a small aperture bypass, then reinjected into the ring where the perturbing effects of the FEL are damped out. 8 refs., 7 figs.
Date: May 1, 1985
Creator: Jackson, A.; Garren, A.A. & Vignola, G.
Object Type: Article
System: The UNT Digital Library
Metal vapor vacuum arc (MEVVA) high current ion source (open access)

Metal vapor vacuum arc (MEVVA) high current ion source

An ion source is described in which a metal vapor vacuum arc is used to create the plasma from which the ions are extracted. Beams of a variety of ions have been produced, ranging from lithium up to uranium. At an extraction voltage of 25 kV we've measured an ion beam current of over 1 Ampere, with over 550 ema of the beam in an emittance of 0.07..pi.. cm. mradians (normalized). The ion charge state distribution varies with cathode material and with arc power; for uranium a typical distribution is peaked at U/sup 5 +/, with up to 40% of the beam current in this charge state. 27 refs., 10 figs.
Date: May 1, 1985
Creator: Brown, I.G.
Object Type: Article
System: The UNT Digital Library
Difficulties with inferring neutron cross sections from charged-particle reactions (open access)

Difficulties with inferring neutron cross sections from charged-particle reactions

We have investigated problems associated with inferring cross sections for neutron reactions on unstable nuclei in the mass-90 region from charged-particle reactions on nearby stable targets. We conclude that effects due to precompound evaporation, isospin, and multiple reaction paths severely limit the circumstances under which charged-particle studies may be directly and easily converted to neutron cross sections of useful accuracy. 4 refs., 2 figs.
Date: May 7, 1985
Creator: Gardner, D. G. & Gardner, M. A.
Object Type: Article
System: The UNT Digital Library
Compact heavy ion RFQ preaccelerator for use at the CERN Linac I (open access)

Compact heavy ion RFQ preaccelerator for use at the CERN Linac I

This paper describes the LBL contribution to a project designed to provide fully-stripped oxygen beams for acceleration in the CERN PS complex. A preaccelerator for Linac I, consisting of an ECR ion source, an RFQ linac, and rf matching cavities, is being assembled as part of a collaborative arrangement among LBL, GSI, and CERN. The RFQ, designed and built at LBL, will accept analyzed oxygen +6 beam from the ECR at 5.6 keV/amu, and accelerate it to 139.5 keV/amu, the injection energy required for 2 ..beta..lambda operation of Linac I. Stripping to +8 will be done with a foil stripper at 12.5 MeV/amu at the exit of Linac I. The RFQ operates at 202.56 MHz and is 0.86 meters in length. The structure is stabilized with vane coupling rings, and uses a single drive loop and a single tuning loop. 5 refs., 3 figs.
Date: May 1, 1985
Creator: Gough, R.A.; Staples, J.; Caylor, R.; Howard, D.; MacGill, R. & Tanabe, J.
Object Type: Article
System: The UNT Digital Library
LBL neutralized beam focusing experiment (open access)

LBL neutralized beam focusing experiment

An intense neutralized Cs/sup +1/ beam has been focused by an electrostatic polarization field induced by a solenoidal magnetic field of 10-25 gauss. This report describes the experiment and compares the results with the predictions of an analytic linearized fluid model and a particle-in-cell simulation which treats the motion of the warm electrons in detail.
Date: May 1, 1985
Creator: Krafft, G. A.; Kim, C. H. & Smith, L.
Object Type: Article
System: The UNT Digital Library
Search for new effects in e/sup +/e/sup -/ interactions (open access)

Search for new effects in e/sup +/e/sup -/ interactions

Recent measurements of R, the ratio of the total hadron cross section to the lowest order muon pair cross section, are discussed which have systematic overall scale errors on the absolute value of R of 7% or less. Experiments are reviewed that have sought exotic effects in e/sup +/e/sup -/ at the highest available energies. The search for narrow states in the radiative decays of the J/psi and UPSILON are also reviewed. 35 refs., 24 figs. (LEW)
Date: May 1, 1985
Creator: Bloom, E.D.
Object Type: Article
System: The UNT Digital Library