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Cable Design for Fast Ramped Superconducting Magnets (Cos-θ Design). (open access)

Cable Design for Fast Ramped Superconducting Magnets (Cos-θ Design).

The new heavy ion synchrotron facility proposed by GSI will have two superconducting magnet rings in the same tunnel, with rigidities of 300 T-m and 100 T-m. Fast ramp times are needed, which can cause significant problems for the magnets, particularly in the areas of ac loss and magnetic field distortion. The development of the low loss Rutherford cable that can be used is described, together with a novel insulation scheme designed to promote efficient cooling. Measurements of contact resistance in the cable are presented and the results of these measurements are used to predict the ac losses, in the magnets during fast ramp operation. For the high energy ring, a lm model dipole magnet was built, based on the RHIC dipole design. This magnet was tested under boiling liquid helium in a vertical cryostat. The quench current showed very little dependence on ramp rate. The ac losses, measured by an electrical method, were fitted to straight line plots of loss/cycle versus ramp rate, thereby separating the eddy current and hysteresis components. These results were compared with calculated values, using parameters which had previously been measured on short samples of cable. Reasonably good agreement between theory and experiment was found, …
Date: March 22, 2004
Creator: Ghosh, A.
System: The UNT Digital Library
Design of the Bnl Super Neutrino Beam Facility (open access)

Design of the Bnl Super Neutrino Beam Facility

A very long base line super neutrino beam facility is need to determine the neutrino mixing amplitudes and phase accurately, as well as the CP violation parameters. This is possible due to the long distance and wideband nature of the neutrino beam for the observation of several oscillations from one species of the neutrino to the other. BNL plans to upgrade the AGS proton beam from the current 0.14 MW to higher than 1.0 MW and beyond for such a neutrino facility which consists of three major subsystems. First is a 1.2 GeV superconducting linac to replace the booster as injector for the AGS, second is the performance upgrade for the AGS itself for the higher intensity and repetition rate, and finally is target and horn system for the neutrino production. The major contribution for the higher power is from the increase of the repetition rate of the AGS form 0.3 Hz to 2.5 Hz, with moderate increase from the intensity. The design consideration to achieve high intensity and low losses for the linac and the AGS will be reviewed. The target horn design for high power operation and easy maintenance will also be presented.
Date: March 22, 2004
Creator: Weng, W. T.; Alessi, J. & Beavis, D. Et Al.
System: The UNT Digital Library
Effect of Colorspace Transformation, the Illuminance Component, and Color Modeling on Skin Detection (open access)

Effect of Colorspace Transformation, the Illuminance Component, and Color Modeling on Skin Detection

Skin detection is an important preliminary process in human motion analysis. It is commonly performed in three steps: transforming the pixel color to a non-RGB colorspace, dropping the illumination component of skin color, and classifying by modeling the skin color distribution. In this paper, we evaluate the effect of these three steps on the skin detection performance. The importance of this study is a new comprehensive colorspace and color modeling testing methodology that would allow for making the best choices for skin detection. Combinations of nine colorspaces, the presence of the absence of the illuminance component, and the two color modeling approaches are compared. The performance is measured by using a receiver operating characteristic (ROC) curve on a large dataset of 805 images with manual ground truth. The results reveal that (1) the absence of the illuminance component decreases performance, (2) skin color modeling has a greater impact than colorspace transformation, and (3) colorspace transformations can improve performance in certain instances. We found that the best performance was obtained by transforming the pixel color to the SCT, HSI, or CIELAB colorspaces, keeping the illuminance component, and modeling the color with the histogram approach.
Date: March 22, 2004
Creator: Jayaram, S; Schmugge, S; Shin, M C & Tsap, L V
System: The UNT Digital Library
Precision short-pulse damage test station utilizing optical parametric chirped-pulse amplification (open access)

Precision short-pulse damage test station utilizing optical parametric chirped-pulse amplification

The next generation of high-energy petawatt (HEPW)-class lasers will utilize multilayer dielectric diffraction gratings for pulse compression, due to their high efficiency and high damage threshold for picosecond pulses. The peak power of HEPW lasers will be determined by the aperture and damage threshold of the final dielectric grating in the pulse compressor and final focusing optics. We have developed a short-pulse damage test station for accurate determination of the damage threshold of the optics used on future HEPW lasers. Our damage test station is based on a highly stable, high-beam-quality optical parametric chirped-pulse amplifier (OPCPA) operating at 1053 nm at a repetition rate of 10 Hz. We present the design of our OPCPA system pumped by a commercial Q-switched pump laser and the results of the full system characterization. Initial short-pulse damage experiments in the far field using our system have been performed.
Date: March 22, 2004
Creator: Jovanovic, I; Brown, C; Wattellier, B; Nielsen, N; Molander, W; Stuart, B et al.
System: The UNT Digital Library
Recent Development in Hydrogen Peroxide Pumped Propulsion (open access)

Recent Development in Hydrogen Peroxide Pumped Propulsion

This paper describes the development of a lightweight high performance pump-fed divert and attitude control system (DACS). Increased kinetic Kill Vehicles (KV) capabilities (higher .v and acceleration capability) will especially be needed for boost phase engagements where a lower mass KV DACS enables smaller overall interceptors. To increase KV performance while reducing the total DACS dry mass (<10 kg), requires a design approach that more closely emulates those found in large launch vehicles, where pump-fed propulsion enables high propellant-mass-fraction systems. Miniaturized reciprocating pumps, on a scale compatible with KV applications, offer the potential of a lightweight DACS with both high {Delta}v and acceleration capability, while still enabling the rapid pulsing of the divert thrusters needed in the end-game fly-in. Pumped propulsion uses lightweight low-pressure propellant tanks, as the main vehicle structure and eliminates the need for high-pressure gas bottles, reducing mass and increasing the relative propellant load. Prior work used hydrazine and demonstrated a propellant mass fraction >0.8 and a vehicle propulsion dry mass of {approx}3 kg. Our current approach uses the non-toxic propellants 90% hydrogen peroxide and kerosene. This approach enables faster development at lower costs due to the ease of handling. In operational systems these non-toxic propellants can …
Date: March 22, 2004
Creator: Ledebuhr, A. G.; Antelman, D. R.; Dobie, D. W.; Gorman, T. S.; Jones, M. S.; Kordas, J. F. et al.
System: The UNT Digital Library
Stability of a Finite-Length Screw Pinch Revisited (open access)

Stability of a Finite-Length Screw Pinch Revisited

None
Date: March 22, 2004
Creator: Ryutov, D. D.; Cohen, R. H. & Pearlstein, L. D.
System: The UNT Digital Library