A New Linear Inductive Voltage Adder Driver for the Saturn Accelerator

Saturn is a dual-purpose accelerator. It can be operated as a large-area flash x-ray source for simulation testing or as a Z-pinch driver especially for K-line x-ray production. In the first mode, the accelerator is fitted with three concentric-ring 2-MV electron diodes, while in the Z-pinch mode the current of all the modules is combined via a post-hole convolute arrangement and driven through a cylindrical array of very fine wires. We present here a point design for a new Saturn class driver based on a number of linear inductive voltage adders connected in parallel. A technology recently implemented at the Institute of High Current Electronics in Tomsk (Russia) is being utilized[1]. In the present design we eliminate Marx generators and pulse-forming networks. Each inductive voltage adder cavity is directly fed by a number of fast 100-kV small-size capacitors arranged in a circular array around each accelerating gap. The number of capacitors connected in parallel to each cavity defines the total maximum current. By selecting low inductance switches, voltage pulses as short as 30-50-ns FWHM can be directly achieved.Comment: 3 pages, 4 figures. This paper is submitted for the 20th Linear Accelerator Conference LINAC2000, Monterey, C

New ground-based observational methods and instrumentation for asteroseismology

Space instrumentation like SOHO, MOST, CoRoT and Kepler has been and is being built to attain very high precision data to be used for asteroseismic analysis. Nonetheless, there is a very strong need for providing additional information, especially on mode identification. With this contribution I will review the efforts been put on new ground-based instrumentation and the methodology that can be used to achieve this aim.Comment: 6 pages. Review contribution to be published in Astrophysics and Space Science Proceedings series (ASSP), in the proceedings of "20th Stellar Pulsation Conference Series: Impact of new instrumentation and new insights in stellar pulsations", 5-9 September 2011, Granada, Spai

Real time Faraday spectrometer

This invention is comprised of a charged particle spectrometer that contains a detection system which embodies the benefits of both foil-light emissions and faraday cups, yet it does not interfere with the particle beam. 5 Figs. (GHH

Current enhancement update

Net current enhancement to levels in excess of the beam current has been observed in gases at pressures excess of 50 torr. We delineate the regimes where enhancement is observed. The experimental results fall into two very distinct classes; current enhancement at injection where the beam is only slightly displaced and current enhancement clearly associated with the high amplitude hose instability. A careful theoretical and experimental study of the diagnostics revealed no fundamental flaws although there are several complex and unlikely scenarios which could introduce fictitious current enhancement. Theoretical efforts indicate several mechanisms for generating enhancement but none of the theories can account for the detailed observations. 4 references, 4 figures

Orbital parameters, masses and distance to Beta Centauri determined with the Sydney University Stellar Interferometer and high resolution spectroscopy

The bright southern binary star beta Centauri (HR 5267) has been observed with the Sydney University Stellar Interferometer (SUSI) and spectroscopically with the ESO CAT and Swiss Euler telescopes at La Silla. The interferometric observations have confirmed the binary nature of the primary component and have enabled the determination of the orbital parameters of the system. At the observing wavelength of 442 nm the two components of the binary system have a magnitude difference of 0.15. The combination of interferometric and spectroscopic data gives the following results: orbital period 357 days, semi-major axis 25.30 mas, inclination 67.4 degrees, eccentricity 0.821, distance 102.3 pc, primary and secondary masses M1 = M2 = 9.1 solar masses and absolute visual magnitudes of the primary and secondary M1V = -3.85 and M2V = -3.70. The high accuracy of the results offers a fruitful starting point for future asteroseismic modelling of the pulsating binary components.Comment: 10 pages, 4 figures. Accepted for publication in MNRA

Fielding and calibration issues for diamond photoconducting detectors

Diamond photoconducting detectors are routinely fielded as soft x-ray diagnostics on Sandia`s Saturn facility. We have developed an improved detector mount that provides a 200-ps time response, is easily cleanable, and is very rugged. In addition, we have developed a new, fast insertion unit to apply bias voltage to the detectors. Absolute calibration of the PCDs is carried out either at the Brookhaven National Synchrotron Light Source or on Sandia`s laser calibration facility. We are now fielding diamond elements that have the dimensions 1x3x0.5 nun and 1x1xO.5 mm. We are neutron damaging some of the 1x1xO.5-mm detectors to reduce their sensitivity. We can tailor PCD sensitivity by adjusting element size and neutron damage level

Field Blue Stragglers and Related Mass Transfer Issues

This chapter contains my impressions and perspectives about the current state of knowledge about field blue stragglers (FBS) stars, drawn from an extensive literature that I searched. I conclude my review of issues that attend FBS and mass transfer, by a brief enumeration of a few mildly disquieting observational facts.Comment: Chapter 4, in Ecology of Blue Straggler Stars, H.M.J. Boffin, G. Carraro & G. Beccari (Eds), Astrophysics and Space Science Library, Springe

Status of beam transport with the ETA and ATA accelerators

Both the Experimental Test Accelerator (ETA) and the Advanced Test Accelerator (ATA) are 10 kA electron induction linacs. The ETA produces a 4.5 MeV, 30 ns pulse, and the ATA a 50 MeV, 70 ns pulse. The ETA has been operational since 1979, having produced over 6 million pulses. Both the beam breakup instability and lower frequency transverse motions of the beam have been suppressed by accelerator cavity damping and with a wire damping zone. These efforts will be summarized. The ATA has become operational within this last year. Full beam current operation has not yet been achieved because of low-frequency transverse motion and centroid drift of the beam. The beam breakup instability has also been observed but does not disrupt the beam. Efforts at finding the source of the drift and low frequency motion, as well as wire damping of these motions will be reported. 6 references, 6 figures

Beam dynamics in the ETA and ATA 10 kA linear induction accelerators: observations and issues

The 10 kA ETA and ATA linear induction accelerators are described. Beam instability is the major concern in these high current machines, and the current status of theoretical understanding, and experimental investigations with the 8 cavity ETA, are reviewed. Modifications to the induction cavities are described that have essentially eliminated the transverse resonant modes seen in the ETA