Rotary Feedthrough Research Articles

Development of an accelerator-based neutron source to prototype Mo-99 production, Part II: A liquid LBE loop under a high vacuum

To provide US domestic supply of Mo-99 without using high-enriched uranium (HEU), a subcritical uranium target assembly (UTA) is irradiated by an accelerator-based neutron source to create Mo-99 through fission. Part I of this work discusses the design of a liquid lead–bismuth eutectic (LBE) windowless target for an accelerator-based neutron source development. Part II discusses how to couple this windowless target to an accelerator operating at an ultra-high vacuum and the subcritical UTA cooled by water at room temperature.Due to the windowless design of the target, the liquid LBE flow shares an ultra-high vacuum (<1.3 × 10−7 Pa or 10−9 Torr) space with the accelerator. As a result of this shared vacuum space, the LBE system must operate at a high vacuum (10−3 ∼ 10−6 Pa or 10−5 ∼ 10−8 Torr). A magnetic rotary motion feedthrough unit utilizes magnetic fluid to allow rotation of the pump while maintaining a high vacuum environment. Prior to testing the LBE system under vacuum, a pump curve measurement is performed to estimate flowrate in the system. This measurement also generates data on orifice loss coefficients, which are compared to correlations in literature. The second experiment investigates vacuum level in the LBE system during operation. High vacuum is maintained (10−3 ∼ 10−5 Pa or 10−5 ∼ 10−7 Torr) during system operation, and a residual gas analyzer (RGA) scan shows that partial pressures of residual gases in the LBE system lower over the duration of LBE system operations. The third experiment investigates the gravity driven liquid LBE flowing out of the target chamber in the return line, which is partially full. If the liquid LBE is not drained quickly enough, flooding in the target chamber could occur. The coefficient n in the Manning equation is found to be around 0.008 s/m1/3. The last experiment performed is a demonstration that a vacuum jacket could provide sufficient thermal insulation to allow coupling between 300 °C LBE loop and a water tank at room temperature. The results from these experiments have influenced the development of the neutron source for the future commercial scale Mo-99 production system.

Beamline commissioning for microscopic measurements with ultraviolet and soft X-ray beam at the upgraded beamline BL-13B of the Photon Factory.

Beamline 13 of the Photon Factory has been in operation since 2010 as a vacuum ultraviolet and soft X-ray undulator beamline for X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), and angle-resolved photoelectron spectroscopy (ARPES) experiments. The beamline and the end-station at branch B have been recently upgraded, enabling microscopic XPS, XAS, and ARPES measurements to be performed. In 2015, a planar undulator insertion device was replaced with an APPLE-II (advanced planar polarized light emitter II) undulator. This replacement allows use of linear, circular, and elliptical polarized light between 48 and 2000 eV with photon intensities of 109-1013 photons s-1. For microscopic measurements, a toroidal post-mirror was renewed to have more focused beam with profile sizes of 78 µm (horizontal) × 15 µm (vertical) and 84 µm × 11 µm at photon energies of 100 and 400 eV, respectively. A high-precision sample manipulator composed of an XYZ translator, a rotary feedthrough, and a newly developed goniometer, which is essential for microscopic measurements, has been used to control a sample specimen in six degrees of freedom, i.e. translation in the X, Y, and Z directions and rotation in the polar, azimuthal, and tilt directions. To demonstrate the performance of the focused beams, one- and two-dimensional XPS and XAS scan measurements of a copper grid have been performed. It was indicated from analysis of XPS and XAS intensity maps that the actual spatial resolution can be determined by the beam size.

Design and construction of a linear motion drive and sample transfer system

Our article focuses on a novel mechanism designed for a linear motion drive, suitable for 250 mm of travel length and compatible with ultrahigh vacuum. As a case study, this mechanism is employed for constructing a simple sample transfer system that allows to store and transfer the samples under high vacuum condition without active pumping system. In our design, we use a typical nut-and-bolt concept to transform the axial rotation motion of a rotary feedthrough attached at one end of the long M6 threaded rod (counterpart of bolt) into linear displacement of a greatly simplified disk (counterpart of nut) that carries samples. Our design is extremely simple, compact, highly versatile, cost effective, and can be readily implemented with an off-centered DN40−16CF reducer and standard DN40CF pipe fittings. Our linear motion drive design can be implemented for various applications such as a sample manipulator, sample storage rack, shielding shutter, or a pillar for pole-stick cleaver.

Table-top soft x-ray polarimetry setup with rotatable linearly polarized light source

A table-top soft x-ray polarimetry setup has been developed at the Institute of Precision Optical Engineering for characterizing the polarization properties of mirrors designed for the lightweight asymmetry and magnetism probe project. Based on a Co/C multilayer polarizer mirror, linearly polarized soft x-rays were generated at a wavelength of 4.48 nm, which could be rotated around the beam-propagation direction by using a differentially pumped rotary feedthrough. The setup design and the alignment method are described in detail. The capabilities of this spectrometer were demonstrated through a polarization test on a twin Co/C multilayer polarizer sample, and the results agree well with the expected sine wave.

A high precision flat crystal spectrometer compatible for ultra-high vacuum light source.

We report on a flat crystal spectrometer (FCS) featuring a differently pumped rotary feedthrough and double detectors connected to a crystal chamber by extendable bellows built at the Shanghai EBIT Laboratory. It was designed to overcome defects such as oil contamination, little distance from the detector to the crystal and others of an early FCS equipped at the same laboratory, but still keeps a large detectable angle range of detectors and brings new features and functions such as the Bond method measurement and double-crystal measurement which are based on the two-detector and large bellow design. This new FCS could cover an energy range of measurable photons from 570 eV to 10 keV and reach a vacuum better than 6 × 10-10 Torr and thus is compatible for coupling directly to ultra-high vacuum light sources. Off-line tests of the FCS were undertaken where Kα x-rays from solid titanium were measured and analyzed. Measurements of transitions in He-like argon ions were performed when the spectrometer was directly connected to Shanghai EBIT, and the width of the x-ray source was monitored simultaneously using an x-ray slit imaging system. An observed spectral line broadening was 0.869 eV corresponding to a resolving power of 3600, including Doppler broadening of the x-ray source. Taking account of the measured source width, we made simulations using the SHADOW 3 code and got a nominal resolving power of 6500 for the spectrometer. This high nominal resolving power is due to a longer distance from the crystal to the detector, comparing with that in the early FCS.

Design of the ITER VUV edge imaging spectrometer and R&D for the rotary motional vacuum feed-through

The ITER vacuum ultraviolet (VUV) spectrometer is aimed at monitoring impurity ion species in plasmas, and it consists of three systems, core survey, edge imaging, and divertor spectrometers depending on positions. In the VUV edge imaging spectrometer, a field mirror and a collimation mirror are used for imaging of the light onto the entrance slit of the VUV imaging spectrometer. To optimize the design of the field mirror box in the ITER port plug, the mirror box mock-up was developed to test installation and alignment. Especially, the mirror alignment using a special tilt stage was tested, and the motional feed-through with a double bellows was developed for the shutter operation. The preliminary qualification test for this rotary motional vacuum feed-through was performed to meet the functional requirement of ITER mechanical feed-through. Leak-tightness for over 15,000 times (larger than operation times) of 360 rotation and backward motion was tested for 1N.m loading condition to the axis rod of the feed-through. In the test, the vacuum inside of the feed-through was monitored, and the feed-through showed good rotation function and leak-tightness during test.

Cantilever stress measurements for pulsed laser deposition of perovskite oxides at 1000 K in an oxygen partial pressure of 10(-4) millibars.

An in situ stress measurement setup using an optical 2-beam curvature technique is described which is compatible with the stringent growth conditions of pulsed laser deposition (PLD) of perovskite oxides, which involves high substrate temperatures of 1000 K and oxygen partial pressures of up to 1 × 10(-4) millibars. The stress measurements are complemented by medium energy electron diffraction (MEED), Auger electron spectroscopy, and additional growth rate monitoring by a quartz microbalance. A shielded filament is used to allow for simultaneous stress and MEED measurements at high substrate temperatures. A computer-controlled mirror scans an excimer laser beam over a stationary PLD target. This avoids mechanical noise originating from rotating PLD targets, and the setup does not suffer from limited lifetime issues of ultra high vacuum (UHV) rotary feedthroughs.

Development of a Contactless Pitch Angle Measurement System

In this article a pitch angle sensor is described that can be installed in a wind turbine as add-on sensor, e.g., for research purposes. One of the most important features of this sensor is that it does neither interfere with the sensory system nor with the control system of the wind turbine. Since it does not contain any electric or electronic components in the rotating hub, it does not use the rotary feedthrough of the wind turbine. The proposed system is based on distance measurement using a laser sensor. Hence, the pitch angle is measured remotely without contact taking place. The components of the system are described, and guidelines for dimensioning these components are given. Such a sensor is installed at a wind turbine; hence the performance is illustrated with measured time series. The conclusion is that the proposed sensor is simple in its design and that it works reliably.

Highly precise and compact ultrahigh vacuum rotary feedthrough

The precision and rigidity of compact ultrahigh vacuum (UHV) rotary feedthroughs were substantially improved by preparing and installing an optimal crossed roller bearing with mounting holes. Since there are mounting holes on both the outer and inner races, the bearing can be mounted directly to rotary and stationary stages without any fixing plates and housing. As a result, it is possible to increase the thickness of the bearing or the size of the rolling elements in the bearing without increasing the distance between the rotating and fixing International Conflat flanges of the UHV rotary feedthrough. Larger rolling elements enhance the rigidity of the UHV rotary feedthrough. Moreover, owing to the structure having integrated inner and outer races and mounting holes, the performance is almost entirely unaffected by the installation of the bearing, allowing for a precise optical encoder to be installed in the compact UHV rotary feedthrough. Using position feedback via a worm gear system driven by a stepper motor and a precise rotary encoder, the actual angle of the compact UHV rotary feedthrough can be controlled with extremely high precision.

Ultra-high vacuum compatible image furnace

We report the design of an optical floating-zone furnace for single-crystal growth under ultra-high vacuum (UHV) compatible conditions. The system is based on a commercial image furnace, which has been refurbished to be all-metal sealed. Major changes concern the use of UHV rotary feedthroughs and bespoke quartz-metal seals with metal-O-rings at the lamp stage. As a consequence, the procedure of assembling the furnace for crystal growth is changed completely. Bespoke heating jackets permit to bake the system. For compounds with elevated vapor pressures, the ultra-high vacuum serves as a precondition for the use of a high-purity argon atmosphere up to 10 bar. In the ferromagnetic Heusler compound Cu(2)MnAl, the improvements of purity result in an improved stability of the molten zone, grain selection, and, hence, single-crystal growth. Similar improvements are observed in traveling-solvent floating-zone growth of the antiferromagnetic Heusler compound Mn(3)Si. These improvements underscore the great potential of optical float-zoning for the growth of high-purity single crystals of intermetallic compounds.

Vacuum-compatible pulse selector for free-electron laser

We developed a vacuum-compatible pulse selector for a free-electron laser. A rotating cylinder with eight apertures in a vacuum is driven by a closed-loop stepping motor system through a magnetically coupled rotary feedthrough. A field programmable gate array is used to synchronize the cylinder rotation with a trigger signal of the accelerator at a maximum repetition rate of 60 Hz. We achieved to select specific pulses from a continuous pulse train of the SPring-8 Compact SASE Source.

A 1800 K furnace designed forin situsynchrotron microtomography

A radiation furnace that covers the temperature range from room temperature up to 1800 K has been designed and constructed for in situ synchrotron microtomography. The furnace operates under a vacuum or under any inert gas atmosphere. The two 1000 W halogen heating lamps are water- and air-cooled. The samples are located at the focus of these lamp reflectors on a rotary feedthrough that is connected to a driving rotation stage below the furnace. The X-ray beam penetrates the furnace through two X-ray-transparent vacuum-sealed windows. Further windows can be used for temperature control, sample changing and gas inflow and outflow.

An ultrahigh-vacuum apparatus for resonant diffraction experiments using soft x rays (hν=300–2000 eV)

We have developed an ultrahigh-vacuum instrument for resonant diffraction experiments using polarized soft x rays in the energy range of hnu=300-2000 eV at beamline BL17SU of SPring-8. The diffractometer consists of modified differentially pumped rotary feedthroughs for theta-2theta stages, a sample manipulator with motor-controlled x-y-z-, tilt (chi)-, and azimuth (phi)-axes, and a liquid helium flow-type cryostat for temperature dependent measurements between 30 and 300 K. Test results indicate that the diffractometer exhibits high reproducibility (better than 0.001 degrees ) for a Bragg reflection of alpha-quartz 100 at a photon energy of hnu=1950 eV. Typical off- and on-resonance Bragg reflections in the energy range of 530-1950 eV could be measured using the apparatus. The results show that x-ray diffraction experiments with energy-, azimuth-, and incident photon polarization-dependence can be reliably measured using soft x rays in the energy range of approximately 300-2000 eV. The facility can be used for resonant diffraction experiments across the L-edge of transition metals, M-edge of lanthanides, and up to the Si K-edge of materials.

Rotary reactor for atomic layer deposition on large quantities of nanoparticles

Challenges are encountered during atomic layer deposition (ALD) on large quantities of nanoparticles. The particles must be agitated or fluidized to perform the ALD surface reactions in reasonable times and to prevent the particles from being agglomerated by the ALD film. The high surface area of nanoparticles also demands efficient reactant usage because large quantities of reactant are required for the surface reactions to reach completion. The residence time of the reactant in a fluidized particle bed reactor may be too short for high efficiency if the ALD surface reactions have low reactive sticking coefficients. To address these challenges, a novel rotary reactor was developed to achieve constant particle agitation during static ALD reactant exposures. In the design of this new reactor, a cylindrical drum with porous metal walls was positioned inside a vacuum chamber. The porous cylindrical drum was rotated by a magnetically coupled rotary feedthrough. By rotating the cylindrical drum to obtain a centrifugal force of less than one gravitational force, the particles were agitated by a continuous “avalanche” of particles. In addition, an inert N2 gas pulse helped to dislodge the particles from the porous walls and provided an efficient method to purge reactants and products from the particle bed. The effectiveness of this rotary reactor was demonstrated by Al2O3 ALD on ZrO2 particles. A number of techniques including transmission electron microscopy, Fourier transform infrared spectroscopy, and x-ray photoelectron spectroscopy confirmed that the Al2O3 ALD film conformally coats the ZrO2 particles. Combining static reactant exposures with a very high surface area sample in the rotary reactor also provides unique opportunities for studying the surface chemistry during ALD.

Ferrofluids improve performance, thermal stability

US-based Ferrotec has announced significant improvements to the standard ferrofluid magnetic liquids which provide the sealing function in ferrofluidic vacuum rotary feedthroughs.

Stable five axes cryogenic photoemission manipulator without a differentially pumped rotary feedthrough

We report on the design and construction of an ultrahigh vacuum compatible cryogenic manipulator for angle resolved photoemission spectroscopy. Unlike designs that have been used so far, our design allows five motions (three translational and two angular) without a differentially pumped rotary feedthrough. The design greatly reduces the sample motion upon rotation, which is crucial in automatic data acquisition over a large area in the momentum space. The constructed manipulator shows smooth motions in vacuum and the lowest temperature it could reach is about 8K at the sample position. Angular reproducibilities are found to be about 0.02° for both of the angular motions. The wobbling motion from the rotation around the vertical rotation axis is found to be virtually nonexistent (less than 0.1mm).

Ultra-high Vacuum compatible rotary feedthrough utilizing ultrasonic motor

Ultra-high Vacuum compatible rotary feedthrough utilizing ultrasonic motor

Low-cost alternative to motorized linear and rotary motion feedthroughs

A simple adapter converts a manual motion feedthrough device into its motorized equivalent.

Vacuum

Megatech has introduced the Superseal range of magnetic sealed rotary feedthroughs into the UK. The low-cost rotary motion feedthroughs, manufactured by US-based Rigaku, use no O-rings or magnets within the vacuum environment. Both 3/8 inch and 1/4 inch solid-shaft versions are available, and could be used as an alternative to lip seals in vacuum deposition systems, ion implanters and epitaxial reactors.

A helium beam path for an imaging-plate detector system

A helium beam path for the marresearch imaging plate detector system (X-ray Research GmbH, Norderstedt, Germany) is described. The helium beam path is designed to minimize unwanted air scattering of the primary beam and to reduce absorption of the diffracted beam. The standard marresearch detector system, consisting of the imaging plate detector (online scanner) and the detector base with integrated collimation system, remains unchanged. The beam path consists of a polyethylene bag with the open end fixed to a metal ring. The ring is pressed against the entry window of the imaging plate detector. In this way a sealed volume is created. The primary beam enters into the helium bag through an additional collimating system which is sealed with a thin polyimide window. The crystal and the goniometer head are located inside the helium bag and are connected to the outside spindle axis via a linear and rotary motion feedthrough.