A visible camera diagnostic has been developed to study the Helically Symmetric eXperiment (HSX) limiter plasma interaction. A straight line view from the camera location to the limiter was not possible due to the complex 3D stellarator geometry of HSX, so it was necessary to insert a mirror/lens system into the plasma edge. A custom support structure for this optical system tailored to the HSX geometry was designed and installed. This system holds the optics tube assembly at the required angle for the desired view to both minimize system stress and facilitate robust and repeatable camera positioning. The camera system has been absolutely calibrated and using Hα and C-III filters can provide hydrogen and carbon photon fluxes, which through an S/XB coefficient can be converted into particle fluxes. The resulting measurements have been used to obtain the characteristic penetration length of hydrogen and C-III species. The hydrogen λiz value shows reasonable agreement with the value predicted by a 1D penetration length calculation.

The University of Wisconsin-Madison is continuing design efforts for a vacuum ultraviolet/X-ray Free Electron Laser facility. The design incorporates seeding the FEL to provide fully coherent photon output at energies up to {approx}1 keV. The focus of the present work is to minimize the cost of the facility while preserving its performance. To achieve this we are exploring variations in the electron beam driver for the FEL, in undulator design, and in the seeding mechanism. Design optimizations and trade-offs between the various technologies and how they affect the FEL scientific program will be presented.

In the present article we briefly review some materials research aspects related to ceramic phosphors and discuss both typical characteristics as well as unique features of such optical converters. Devices with more efficiency and/or higher luminous flux that are based on converting the pump light crucially enable the use of LEDs in white and single color illumination schemes for many applications. Advantages of generating white light with ceramics versus powder-in-silicone are discussed. High performance of single color conversion LEDs in terms of efficacy and external quantum efficiency for the visible region boost the output in data or home cinema projection and automotive signaling but more applications are appearing. (C) 2012 The Electrochemical Society.

We report on continuing design efforts for a next generation FEL facility, building on the Wisconsin Free Electron Laser (WiFEL) study [1]. The principal goal is to optimize value by minimizing cost while maximizing scientific reach. The most attractive solution is a very high repetition rate cw FEL complex, implemented in phases. The first phase, for substantially less than one billion dollars, supports a strong initial science program and allows application of the experience gained and welltested innovations to later phases. The additional phases provide an increasingly diverse scientific research program with photon energies extending to hard X-rays.

Many LED-based applications would benefit from more efficient and/or high lumen output devices that enable usage in both white and single color illumination schemes. In the present article we briefly review the materials research history leading to optical ceramic converters and discuss their typical characteristics. Recently demonstrated high performance values in terms of efficacy and external quantum efficiency in orange (amber) spectral region are described.

The University of Wisconsin-Madison/Synchrotron Radiation Center is advancing its design for a seeded VUV/soft X-ray Free Electron Laser facility called WiFEL. To support this vision of an ultimate light source, we are pursuing a program of strategic R&D addressing several crucial elements. This includes development of a high repetition rate, VHF superconducting RF electron gun, R&D on photocathode materials by ARPES studies, and evaluation of FEL facility architectures (e.g., recirculation, compressor scenarios, CSR dechirping, undulator technologies) with the specific goal of cost containment. Studies of high harmonic generation for laser seeding are also planned.

SRC has recently commissioned a new Varied Line-Spacing Plane Grating Monochromator (VLS-PGM) utilizing as its source a 1 m long APPLE II insertion device in short-straight-section 9 of the Aladdin storage ring. The insertion device reliably delivers horizontal, vertical, and right and left circularly polarized light to the beamline. Measurements from an in situ polarimeter can be used for undulator corrections to compensate for depolarizing effects of the beamline. The beamline has only three optical elements and covers the energy range from 11.1 to 270 eV using two varied line-spacing gratings. A plane mirror rotates to illuminate the gratings at the correct angle to cancel the defocus term at all photon energies. An exit slit and elliptical-toroid refocusing mirror complete the beamline. Using a 50 mu m exit slit, the beamline provides moderate to high resolution, with measured flux in the mid 10(12) (photons/s/200 mA) range, and a spot size of 400 mu m horizontal by 30 mu m vertical. (C) 2010 Elsevier B.V. All rights reserved.

Following on the success of lower emittance operation at 800 MeV, SRC is pursuing a number of additional enhancements to the performance of the Aladdin storage ring. Work on Aladdin has included development of low emittance lattices at 1 GeV, which will maximize the capabilities of a recently installed spectromicroscopy beamline and a proposed high-resolution keV beamline. Installation of one-meter long insertion devices in the short straight sections within the quadrant arcs of the four sided storage ring is being pursued to increase the number of undulator beamlines from four to possibly eight. Studies have been made to determine what is the minimum insertion device gap that does not interfere with nominal ring operation (injection, ramping, and lifetime at full energy), and indicate that smaller-gapped devices for higher photon energy are reasonable. Lifetime increases or further emittance reductions appear possible with modest aperture increases at a small number of points on the ring. Finally, planning is under way for long term projects such as a new injector or a next generation VUV/soft-xray source for the Midwest. Details are presented.

The Synchrotron Radiation Center operates the Aladdin electron storage ring at energies of 800 meV or 1 GeV in support of a broad range of national and international research programs with a major focus on the study of valence electrons, spectromicroscopy, and nanolithography. Upgrades to the storage ring have improved the stability of the source, and experiments with low emittance lattice configurations show the feasibility of increased brightness for new or enhanced research. Three recently installed undulators, two pure permanent magnet devices and an electromagnetic device, and the associated instrumentation offer experimentalists high flux combined with high resolution. The status of the existing instrumentation, recent scientific results, and an overview of plans for new undulator-based instruments to cover the photon energy range from 7.8 to 400+ eV will be presented.

During the last years GaN-technology has proven to fulfill the requirements of solid state lighting. Lighting requirements are mainly driven by brightness, operation voltage and lifetime. Brigthness is determined by internal efficiency as well as extraction efficiency whereas the ohmic losses determining the operating voltage are dominated by series resistance and contact resistance. Both, brightness and voltage, strongly depend on the device structure as well as the chip design. SiC based [1, 2] as well as Sapphire based LEDs [3] have proven their capability for high brightness devices, still suffering from various compromises such as cost, ESD-stability, high series resistance etc.Recently OSRAM-OS has demonstrated its newly developed product line based on the so called ThinGaN(TM) technology, a true thinfilm approach that overcomes most of the compromises mentioned. The technology allows highest brightness levels at lowest operating voltage, is scalable and supports all wavelengths. The devices act as true surface en-titters with a lambertian emission pattern.

Solid state lighting has seen a rapid development over the last decade. They compete and even outperform ligth sources like incandescent bulbs and halogen lamps. LEDs are used in applications where brightness, power consumption, reliability and costs are key parameters as automotive, mobile and display applications. hi the future LEDs will also enter the market of general lighting. For all of these new applications highly efficient, scalable and cost efficient technologies are required.These targets can be matched by SiC based flip chip LEDs which enable the design of high current chips with efficiencies of up to 28 lm/W in white solderable packages. An alternative approach is the implementation of thinfilm technology for GaInN. The LED is fabricated by transferring the epilayers with laser lift off from sapphire to a GaAs host substrate. In combination with efficient surface roughening and highly reflective p-mirror metallisation an extraction efficiency of 70% and wall plug efficiency of 24% at 460nm have been shown. The chips showed 16mW @ 20mA with an Voltage of 3.2V. The technology is scalable from small size LEDs to high current Chips and is being transferred to mass production.

On the recent LED designs three different main paths can be observed. First, low cost, shrinked devices operating at low voltage are focus of mobilecom application, second, high brightness devices driven at 20mA are targeted for mass markets such as the automotive market and third, high optical power devices for high flux outdoor light sources and general lighting are in the technological focus. All of these devices focus on high quantum and high extraction efficiencies leading to overall efficiencies as high as 2530 lm/W and absolute light output as high as 30 lm of white light per single device. To reach such numbers new technologies on light generation and extraction have been developed. Another main path of research is focused on laser devices where applications as high optical data storage density, high resolution printing, spectroscopy & sensing, projection & display technology as well as general lighting are targeted. The laser research of today aims on especially long lifetime at elevated temperatures which is still the limiting factor to start mass market applications. Most likely these markets will develop in the next years, e.g. 2004 is addressed for "Blu-ray" DVD applications.

Data are presented for an GaInN based thinfilm LED. The LED is fabricated by transferring the epilavers with laser lift off from sapphire to a GaAs host substrate. In combination with efficient surface roughening and highly reflective p-mirror metallisation an extraction efficiency of 70% and wall plug efficiency of 24% at 460mn have been shown. The chips showed 12mW @ 20mA with an Voltage of 3.2V. The technology is scalable front small size LEDs to high current Chips and is being transferred to mass production.

We are in the process of upgrading the VME processors on the Aladdin electron-storage-ring control system. The last major redesign of the control system occurred in the mid 1980's. At that time we converted to VME microcomputers and VAX/VMS workstations communicating via Ethernet. This is the second upgrade since then of the VME processor. As upgrades of the Motorola 680x0 processor are no longer available we have decided to switch to the Intel Pentium III. This change allowed us to reconsider our use of the rather primitive muC/OS kernel and implement a commercial real-time OS. We decided to use QNX primarily as it was a good match to our existing software and was zero cost. In addition to upgrading the CPUs we have also added a new scripting language to our main control application. We used SWIG (Simplified Wrapper and Interface Generator) to create wrapper code for the scripting software. SWIG can create wrapper code for many scripting languages so our initial choice of a scripting language was not critical. We decided to start by using Python due to the many available add-on libraries and the apparent ability to support larger projects. We will discuss our evaluation process and the challenges we encountered.

The Aladdin storage ring is now routinely run in a low emittance configuration at 800 MeV. Vertical beam sizes and lifetime are comparable to the original lattice, while the horizontal beam size is reduced by a factor of three. Tools used to commission the new lattice include model based correction to obtain the design machine functions, and model independent correction to set the desired transverse coupling. Newly installed optical profile and position monitors, shunts to trim individual magnets, as well as implementation of a new control system scripting language, were important in achieving the desired results. Special attention was given to operation of the fourth harmonic bunch lengthening cavity used to improve the beam lifetime, and noise reduction in the RF system to improve photon beam quality on the infrared beamlines. In addition, compensation of undulators allows their strengths to be varied with minimum perturbation to the beam outside the regions of the undulators. Details of bringing the low emittance lattice to operational readiness are presented.

LED chip for flip-chip mounting on a lotbedeckten carrier, with - a conductive substrate (12), - is connected to a semiconductor body (14) comprising a photon-emitting active zone, and with a bottom with the substrate (12), and - arranged one on an upper surface of the semiconductor body (14) contact (18) for producing an electrically conductive connection with the carrier (30) in the flip chip of the chip, - an insulation means (40, 42, 44, 46, 48) for electrical insulation of free surfaces of the semiconductor body (14) and the substrate (12) of the solder (32) in the flip-chip mounting of the chip, wherein said isolation means a the free surfaces of the semiconductor body (14) covering electrical passivation layer (40), characterized in that the insulating means further comprises a thin, insulating molecule film (46) which covers the entire free surface of the substrate (12) and the molecules having two functional groups, one of which to the substrate (12) adheres to ...

In December of 2000 the University of Wisconsin Synchrotron Radiation Center (SRC) installed a new, state-of-the-art undulator in long straight section 2 of the Aladdin storage ring. This undulator replaced the first Aladdin undulator, which was on loan from the Stanford Synchrotron Radiation Laboratory and had been in use since 1986 [K. Halbach et al., IEEE Trans. Nucl. Sci. NS-28, 3136 (1981); H. Winick et al., Nucl. Instrum. Methods Phys. Res. A 208, 127 (1983); M. A. Green et al., Nucl. Instrum. Methods Phys. Res. A 266, 91 (1988)]. The new undulator was designed, constructed, and tested by Danfysik (Danfysik A/S, Moellchaves 31A, DK-4040 Jyllinge, Denmark). The undulator uses NdFeB permanent magnets for the magnetic structure and is 3.52 m long with 50 periods, each of 68.3 mm. The new undulator is intended to provide high flux from 7.8 to 500 eV. To cover this wide energy range we use the first through ninth odd harmonics. The magnetic structure has been phase-corrected to better than 2° rms and should provide fidelity better than 90% through the ninth harmonic. The resulting undulator flux will support an extreme ultraviolet nano-lithography beamline, a low energy Wadsworth beam line, and a high energy VLS-PGM beam line. Some coherence experiments are also anticipated. The undulator radiation has been analyzed using an existing HTM [M. C. Hettrick, Nucl. Instrum. Methods Phys. Res. A 266, 404 (1988)] monochromator, a durable filter-pinhole detector, and computer controlled, cooled, scanning apertures. We present measurements of the undulator harmonic content, energy and spatial structure of the undulator beam, and undulator beam position stability.

We investigate the influence of chip size, substrate shaping and mounting techniques on the light extraction efficiency of large area InGaN-LED chips grown on 6H-SiC substrates. New techniques to achieve good light extraction for large chip areas are demonstrated and discussed. Applying these techniques to InGaN on SiC chips with 1 mm(2) size, we generate 150 mW of blue light and 33 lm of white light at a forward current of 350 mA. For efficient light extraction from the chip and for good thermal coupling the chip is soldered up-side down into a newly developed SMT package with a thermal resistance below 10 K/W.

We present brightness improvements of blue InGaN chips on SiC substrates. Chip shape, performance of the contacts, high structural quality of the InGaN quantum well layers are essential for an optical output as high as 9.5 mW at 470 nm and 20 mA. The external quantum efficiency is 18%. The light extraction out of the chip is increased to 55% as calculated by a ray trace simulation. This is the highest value ever reported on InGaN chips, which are conventionally mounted with epitaxial layers upside. The optimized chip side walls have vertical angles of 60degrees. The reflectivity at the p-contact is increased to 90% for flat angles of 0 to 20degrees. An internal quantum efficiency of 32% is estimated from the values of light extraction and external quantum efficiency. The epitaxial layers are improved by optimizing the growth parameters of the quantum wells interfaces. Electrical losses are reduced by better interface quality of epitaxial layers and by an improved p-contact resistance of 10(-4) Omega cm(2), respectively.