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Due to structural limitation, the currently proposed apparatus based on a single sheet tester (SST) cannot measure magnetic properties along arbitrary directions (so-called 2-D magnetic properties) of silicon steel at high flux densities. In this paper, significant improvements are carried out on magnetizing windings and auxiliary yokes of a double excitation type of SST. Furthermore, crosswise overlapped H-coils are introduced so that even an ordinary single-excitation type of SST can be applicable to the measurements of 2-D properties. It is demonstrated that 2-D magnetization property up to 1.9 T can be measured by using the newly developed SST's

A two module electron beam source operating over a wide range of output parameters has been designed and fabricated to be used in conjunction with a pair of electron beam sustained CO/sub 2/ lasers. Each module comprised a grid-controlled thermionic electron beam gun including a compact grid pulser for control of the electron beam, a 250 kV thyratron switched modulator for acceleration of the electron beam, 1 kHz filament heater and a complex computerized control system. Table 1 summarizes the overall system specifications.

Starting in 1984, studies have been made of 15-65 MV, 4 MJ, 9-16 ns ion drivers for the LIBRA ICF reactor. The Helia approach was adopted. Design options and general design considerations are discussed. A recent 30 MV design is described that consists of 16 modules, each of 28 1.3 MV Metglas induction cells, powered by thyratron-switched capacitor banks through magnetic pulse compressors.

The ZR refurbishment project [1] at Sandia National Laboratories (SNL) required a set of diverter switches to protect the Marx generators and intermediate storage (IS) capacitors from Marx pre-fire and/or laser triggered output switch (LTS) no-fire. Thirty-six such diverters, one for each Marx-IS set, will need to operate reliably over the full range of Marx charge voltages and LTS anticipated closure times. Operating voltage is up to 6 MV. A self-closing oil switch diverter was selected and design work began in late 2002. The first diverter (Phase I or just PI) was delivered in the summer of 2003 and tested on SNL's Z20 test-bed. Based on test results, operational experience and overall project budgetary concerns, it was decided to re-design the diverter, resulting a simpler, less costly switch. This new self- closing oil switch (Phase II or P2) was fielded at SNL on the Z20 test-bed in late 2004. Both designs include adjustable electrodes to control the closure time. Also incorporated is a mechanical clamp that minimizes or shorts the oil gap until Marx charge is complete. Both diverters feature liquid resistors sized to safely absorb the energy stored in the Marx or IS. This paper describes the design and test results from these diverters.

The injector for the second axis of the dual-axis radiographic hydrotest facility (DARHT II) is now undergoing commissioning tests at Los Alamos national laboratory. A Marx generator develops a 3.2 MV, 2 /spl mu/s pulse that is applied to the diode through a high voltage (or Marx) dome, current stalk and high voltage insulator column. The 2 kA electron beam source is a 165-mm-diameter thermionic dispenser cathode operating near 120 kV/cm. The extracted beam enters a series of eight pulsed power-driven injector induction cells that accelerate the beam to approximately 4.5 MeV. The beam then passes through a beamhead clean-up zone (BCUZ) to "scrape off" the off-energy portion of the beam (the beam leading edge and, to a lesser extent, the beam trailing edge). A crowbar switch fired at the end of 2 /spl mu/s produces a short fall time. This paper focuses on the electrical and mechanical design and testing of the Marx generator. The Marx consists of 88 stages, each half stage of which is a +/- 50 kV type EPFN. The Marx was tested for over 8000 shots before shipment to Los Alamos and demonstrated 6 ns jitter and good reliability with only 8 prefires out of 5000 shots. At the end of December 2002, nearly 800 shots have been fired in the process of commissioning the DARHT machine. The results of both series of these tests are given in this paper.

The prototypes for the nominally 300-kV pulsed power supply and acceleration cell were built and tested in order to determine critical design parameters needed for their final designs. The pulsed power supply produced a 73-ns-long trapezoidal pulse rising in 3 ns (10-90%) and having high frequency ripple of less than 2%. The power supply's throughput jitter was 1.5 ns (1a). The cell was driven by the power supply and had a resistor taking the place of the beam loading. The cell tests showed that the ferrite had a useful flux swing of 0.45 T (20.7 mV-s) before the magnetization current pulled the cell voltage down by more than a few percent. >

Summary form only given. Cygnus is a prototype of a radiographic X-ray source leveraging existing hardware and designs to drive a rod-pinch diode at 2.2 MV. This high-resolution X-ray source is being developed to support the Sub-Critical Experiments Program at the Nevada Test Site, and as such employs a modular technology that is scaleable to higher voltages and can be readily deployed underground. The diode is driven by three Induction Voltage Adder (IVA) cells from the Sandia SABRE accelerator; threaded by a positive polarity vacuum coax that extends 2 in to the diode and is designed to operate below electron emission on the anodized outer electrode. The /spl sim/40 ohm diode impedance requires a 40/(3*3)/spl sim/4.5 ohm source to drive the three IVA cavities in parallel, a convenient impedance for a single water coax. The water coax is further designed to serve as a long, passive water cable accommodating several bends to allow independent positioning of the pulse generator that drives the coax, the IVA, and diode X-ray source at the far end. This long water coax is driven by a water pulse-forming line originally developed for Sandia's Radiographic Integrated Test Stand (RITS). A low inductance commercial Marx charges the single PFL in times similar to the charge-times of parallel sets of PFLs driven by intermediate stores in larger IVA systems such as RITS, Hermes-III. The paper describes the Cygnus accelerator design and presents test results for some components.

Three-dimensional images of the near-surface atom arrangement were calculated from two-dimensional photoelectron diffraction data by several imaging algorithms: (i) a basic method with a Fourier transformation at one kinetic energy over k space, considering the phase factor due to the path-length difference; (ii) energy summation of the above results; (iii) Fourier transformation within small k-space windows; and (iv) their combinations. Atomic images produced by these methods from the experimental Si 2p photoelectron diffraction patterns of an Si(001) surface are compared with the crystal geometry. The results show that the energy-summed small-window method, called SWEEP, gives the best images.

An acousto-optic (AO) tunable filter will be a key component in future wavelength division multiplexing (WDM) systems, because of its wide tuning range with high speed (a few microseconds) and relatively narrow pass bandwidths (~1 nm). For practical WDM systems, polarization independent tunable optical wavelength filters are indispensable. Previously, these devices, using polarization beam splitters (PBS) controlled by applied voltage, had been demonstrated [1][2]. However, it is advisable not to use many high voltage sources for the device operation. The authors present the polarization independent AO filter (Fig. 1), integrating newly developed passive PBS in LiNb03, for the first time.

A new high-performance 1.3-μm InGaAsP semiconductor laser is described, in which effective current confinement into the active region has been realized. A p-n-p-n current blocking structure is made by liquid-phase epitaxy (LPE) on both sides of the active-stripe mesa which is defined by a pair of channels in the double-heterostructure wafer. The double-channel-planar-buried-heterostructure laser diodes (DC-PBH LD's) exhibit high-laser performances, such as a high differential quantum efficiency of 78-percent maximum, which results in high electrical to optical power conversion efficiency 43 percent, and high light output power of over 50 mW, as a result of the improvement in the current blocking structure. The threshold current temperature sensitivity is found experimentally to be reduced remarkably by increasing the doping concentration in the p-cladding layer. Characteristic temperature as high as 100 K has been obtained. CW operation is possible up to 130°C.

It is very desirable to improve the high-temperature performance characteristics of the 1.5–1.6-μm InGaAsP/InP laser diodes (LDs), which have so far been inferior to those of the 1.3-μm LDs.1 We report improvement in the temperature dependence of 1.52-μm InGaAsP/lnP double-channel planar-buried-heterostructure (DCPBH) LDs,2 which has been achieved by using two-step vapor phase epitaxy (VPE) and liquid phase epitaxy (LPE) crystal growth. We discuss the reason for the temperature-dependence improvement.

lnGaAsP/lnP high-power laser diodes are particularly attractive for a variety of applications as light sources for long-span optical fiber communication systems as well as !or fault-locating measurements, remote sensing, and so on. The stable fundamental transverse mode operation has been established in developing buried heterostructure-type laser diodes. However, the cw operable power has been limited to ~70 mW (Refs. 1 and 2) due to the fairly large temperature dependence of threshold current and current leakage flowing through the blocking layer at the high-injection-current level. In this paper we report 140-mW cw operation at 1.3 µm in lnGaAsP DC-PBH LD. We believe this is the first report on exceeding 100-mW cw operation in lnGaAsP laser diodes.

The effects of refractive index dependence on the active region carrier density in semiconductor laser injection locking have been examined experimentally. Strong asymmetry has been observed in the relation between locked longitudinal mode intensity and the difference between an original longitudinal mode wavelength and the injecting light wavelength.

Continuous-wave operation up to 115°C has been achieved in 1.52 μm InGaAsP double-channel planar-buried-heterostructure laser diodes using two-step VPE and LPE. The high-temperature operation has been found attributable to the reduction in the leakage current bypassing the active region.

The fluctuation of longitudinal modes of a high-bit-rate modulated 1.5 μm InGaAsP/InP laser is greatly improved by injection-locking technology. A 106 km transmission at 300 Mbit/s and 450 Mbit/s was achieved with tolerable transmission losses of 37.2 dB and 36.2 dB, respectively, which implies a potential transmission distance of over 145 km.

The reliability of 1.5 μm InGaAsP/InP DC-PBH lasers prepared by two-step hydride VPE and LPE was estimated at the 70°C, 5 mW constant-power mode. The low degradation rate (8×10−5/h) indicated high reliability of the two-step VPE-LPE-grown LDs with the VPE-grown active layer.

The fabrication and lasing characteristics for planar surface buried-heterostructure InGaAsP/InP lasers with highly resistive current-blocking layers are reported. Embedding growth was successfully performed by Fe-doping hydride VPE. Single transverse mode operation has been realised in lasers with a narrow active region, without any nonradiative recombination increase, due to an Fe-associated deep level. High-frequency response up to 10GHz was also demonstrated.

Practical 4-port and 8-port kaleidoscope micro-optic star couplers for optical-fibre data links have been developed, with the advantages of low insertion losses well balanced among the ports, high reliability, easy fabrication and small size. This coupler utilises image formation by multireflection at the side planes of a cross-sectionally wedge-shaped small rod lens, and is therefore called a kaleidoscope micro-optic star coupler.