SLAC National Accelerator Laboratory is studying an option of building a high brightness synchrot... more SLAC National Accelerator Laboratory is studying an option of building a high brightness synchrotron light source machine, PEP-X, in the existing PEP-II tunnel [1, 2]. By replacing 6 arcs of FODO cells of PEPII High Energy Ring (HER) with two arcs of DBA and four arcs of TME and installation of 89.3 m long damping wiggler an ultra low beam emittance of 0.14 nm-rad (including intra-beam scattering) at 4.5 GeV is achieved. In this paper we study the possibility to further reduce the beam emittance by releasing the constraint of the dispersion free in the DBA straight. The QBA (Quadruple Bend Achromat) cell is used to replace the DBA. The ratio of outer and inner bending angle is optimized. The dispersion function in the non-dispersion straight is controlled to compromise with lower emittance and beam size at the dispersion straight. An undulator of period length 23 mm, maximum magnetic field of 1.053 T, and total periods of 150 is used to put in the 30 straights to simulate the effect...
A lattice for the PEP-X ultimate storage ring light source, having 11 pm-rad natural emittance at... more A lattice for the PEP-X ultimate storage ring light source, having 11 pm-rad natural emittance at a beam energy of 4.5 GeV at zero current, using 90 m of damping wiggler and fitting into the existing 2.2-km PEP-II tunnel, has been recently designed. Such a low emittance lattice requires very strong sextupoles for chromaticity correction, which in turn introduce strong non-linear field effects that limit the beam dynamic aperture. In order to maximize the dynamic aperture we choose the cell phases to cancel the third and fourth order geometric resonances in each 8-cell arc. Four families of chromatic sextupoles and six families of geometric (or harmonic) sextupoles are added to correct the chromatic and amplitude-dependent tunes. To find the best settings of the ten sextupole families, we use a Multi-Objective Genetic Optimizer employing elegant to optimize the beam lifetime and dynamic aperture simultaneously. Then we evaluate dynamic aperture reduction caused by magnetic field mult...
The SPEAR3 accelerator upgrade opened up two 7.6m racetrack straights in the magnet lattice. In o... more The SPEAR3 accelerator upgrade opened up two 7.6m racetrack straights in the magnet lattice. In one of these straights, we recently added a magnetic chicane to separate two insertion device (ID) beam lines by 10mrad. A quadrupole triplet in the center creates a ''double focus'' optics with {beta}y = 1.6m at the middle of each ID, hence the term ''double-waist chicane''. The new optics also reduced {beta}y in the four matching straights adjacent to the racetrack straights to 2.5m. In this paper, we outline design features of the optics and physical implementation of the lattice.
SPEAR3 has a large cross-section copper vacuum chamber, mode-damped RF cavities and mostly low-im... more SPEAR3 has a large cross-section copper vacuum chamber, mode-damped RF cavities and mostly low-impedance insertion devices. As a result, the beam is nearly passivestable for 280-bunch beam currents up to 500 mA when the background gas pressure is low. In the future, more small-gap insertion devices will be installed and plans are underway to implement crabbing systems for short-pulse production. These requirements drive the need for a transverse bunch-by-bunch feedback system (BxB). In this paper we present plans for stripline kickers.
Since its 2003 construction, the SPEAR3 synchrotron light source at SLAC has continuously improve... more Since its 2003 construction, the SPEAR3 synchrotron light source at SLAC has continuously improved its performance by raising beam current, top-off injection, small alpha and smaller emittance. This makes SPEAR3 one of the most productive light sources in the world. Now to further enhance the operation of SPEAR3, we are looking into the possibility of converting SPEAR3 to a multi-bend achromat storage ring within its site constraint.
We describe the design of an FEL Amplifier Test Experiment (FATE) 1 to demonstrate the superradia... more We describe the design of an FEL Amplifier Test Experiment (FATE) 1 to demonstrate the superradiant short bunch regime of a Free Electron Laser in the 1-3 m wavelength range starting from noise. The relevance to the LCLS X-ray FEL [1] proposal is discussed and numerical simulations are shown. It is numerically demonstrated for the first time with the 2-D code GINGER, that clean-up of noise in the superradiant regime occurs even at low power levels.
Adaptation technologies may require new hardware or different implementation approaches ('softwar... more Adaptation technologies may require new hardware or different implementation approaches ('software'). Five main areas of adaptation technology application are: regional and local climate modeling and early warning, coastal zone management, water resources, agriculture and public health. Table 2 provides an indicative list of adaptation technologies in these five areas. Technological progress can take place through: scientific innovation and invention, the adoption and adaptation of pre-existing but new-to-the-market technologies, and the diffusion of technologies. Enormous gaps remain, especially in the case of the least developed countries. Technology development and transfer can be either accelerated or slowed depending on market conditions, fiscal and regulatory policies, availability of finance, access to information, the legal and institutional framework, human resource capacities, and the condition of infrastructure. Each country needs to conduct its own assessment of the most important domestic barriers to clean technology development and transfer. In addition, there are also barriers relating to international trade and associated rules, for example, with respect to intellectual property rights. Financial constraints are most often cited as a barrier to adoption of environmentally sound technologies in those non-Annex I countries which have conducted technology needs assessments. Capital shortages and high capital costs are still commonplace in many developing countries. Underdeveloped financial sectors and inhospitable investment environments are key reasons. These constraints may be tightened by the current global financial crisis. Small domestic markets for low-carbon technologies are another oft-mentioned barrier to technology adoption. Limited information about the availability of technologies and technology suppliers was another frequently cited barrier to technology acquisition. However, the biggest obstacle is that existing technologies are too expensive, making the resulting services unaffordable for the bulk of the populations of non-Annex I countries. Government policies can support or hinder low-carbon energy technology development and transfer. Supportive legal and regulatory frameworks may include energy-efficiency codes for buildings, fuel efficiency standards for motor vehicles and mandates for renewable energy use. Given cost disadvantages still faced by many non-conventional energy sources, government subsidies, feed-in tariffs and other support can facilitate adoption, but these may require international support. Rapid adoption of alternative energy technologies is hindered by subsidized conventional energy prices. However, removal of the subsidies without an increase in income or the availability of other affordable energy services could be both inequitable and socially unacceptable. IGCC 1 commercialization Solid oxide fuel cells Cleaner coal plants Hydrogen (H 2) co-production from coal/biomass Hydrogen Integrated stationary fuel cell systems Demonstration H 2 production from renewable sources Low cost H 2 storage and delivery. H 2 from renewable sources. Renewable H 2powered fuel cell vehicles H 2 and electric economy Renewable energy Lower cost wind power Demonstration cellulosic ethanol Photovoltaic (PV) clad buildings. Cost-competitive solar PV First-generation bio-refinery Low-wind speed turbines Advanced bio-refineries Cellulosic biofuels Community-scale solar systems Water photolysis Energy storage options Widespread renewable energy utilisation Genetically engineered biomass Biologically inspired energy and fuels Nuclear fission & fusion Advanced reactor and fuel cycle technology Generation IV nuclear plants. Fusion plant demonstration Advanced concepts for waste reduction. Fusion power plants Reforestation Soil conservation Sequestration decision support tools. Bio-based and recycled products Biological sequestration Carbon and CO 2 based products and materials Marine sequestration Effective dilution of directly injected CO 2 Carbonate dissolution/alkaline addition Safe long-term marine storage EMISSION REDUCTION OF OTHER GHGs Methane from energy production and waste Bioreactor landfill technology New drilling techniques for recovery of coal-bed methane Advanced landfill gas utilization. Ventilation-air methane technologies Integrated waste management systems Methane and N 2 O from agriculture Anaerobic digesters for heat and electricity production Utilisation of soil microbial processes Zero-emission agriculture High global warming potential gases Advanced refrigeration technologies. Advanced aluminium smelting processes Alternative refrigeration fluids Solid-state refrigeration and air conditioning systems N 2 O from combustion Catalytic reduction of N 2 O in nitric oxide plants Catalysts that reduce N 2 O to elemental nitrogen in diesel engines Advanced vehicles and noncarbon based fuels Require a well-specified research objective xviii 1 I.
Over the past year, we have worked out a baseline design for PEP-X, as an ultra-low emittance sto... more Over the past year, we have worked out a baseline design for PEP-X, as an ultra-low emittance storage ring that could reside in the existing 2.2-km PEP-II tunnel. The design features a hybrid lattice with double bend achromat cells in two arcs and theoretical minimum emittance cells in the remaining four arcs. Damping wigglers reduce the horizontal emittance to 86 pm-rad at zero current for a 4.5 GeV electron beam. At a design current of 1.5 A, the horizontal emittance increases, due to intra-beam scattering, to 164 pm-rad when the vertical emittance is maintained at a diffraction limited 8 pm-rad. The baseline design will produce photon beams achieving a brightness of 10²² (ph/s/mm²/mrad²/0.1% BW) at 10 keV in a 3.5-m conventional planar undulator. Our study shows that an optimized lattice has adequate dynamic aperture, while accommodating a conventional off-axis injection system. In this paper, we will present the study of the lattice properties, nonlinear dynamics, intra-beam sca...
With the recent success in commissioning of MAX IV, the multi-bend achromat (MBA) lattice has beg... more With the recent success in commissioning of MAX IV, the multi-bend achromat (MBA) lattice has begun to deliver on its promise to usher in a new generation of higher-brightness synchrotron light sources. In this paper, we begin by reviewing the challenges, recent success, and lessons learned of the MAX-IV project. Drawing on these lessons, we then describe the physics challenges in even more ambitious rings and how these can be met. In addition, we touch on engineering issues and choices that are tightly linked with the physics design.
We completed a design of PEP-X [1] as a highbrightness light source that could reside in the exis... more We completed a design of PEP-X [1] as a highbrightness light source that could reside in the existing 2.2km PEP-II tunnel. The design features a hybrid lattice with double bend achromat (DBA) cells in two arcs and theoretical minimum emittance (TME)cells in the remaining four arcs. The baseline design will produce photon beams achieving a brightness of 10 22 (ph/s/mm 2 /mrad 2 /0.1% BW) at 10 keV in a 3.5-m conventional planar undulator. Our study shows that an optimized lattice has adequate dynamic aperture, while accommodating a conventional offaxis injection system. In the paper, we will summarize the results of the study, including the lattice properties, nonlinear dynamics, intra-beam scattering and Touschek lifetime, and collective instabilities. This future light source has a potential to reach high coherence in both transverse dimensions for multi-keV photons and to lase partially in a very long undulator at soft x-ray wavelengths. Achieving these features would make this st...
We have designed an “ultimate” storage ring for the PEP-X light source that achieves the diffract... more We have designed an “ultimate” storage ring for the PEP-X light source that achieves the diffraction limited emittances (at 1.5 ˚A) of 12 pm-rad in both horizontal and vertical planes with a 4.5-GeV beam. These emittances include the contribution of intrabeam scattering at a nominal current of 200 mA in 3300 bunches. This quality beam in conjunction with a conventional 4-m undulator in a straight section can generate synchrotron radiation having a spectral brightness above 10 22 [photons/s/mm 2 /mrad 2 /0.1% BW] at a 10 keV photon energy. The high coherence at the diffraction limit makes PEP-X competitive with 4th generation light sources based on an energy recovery linac. In addition, the beam lifetime is several hours and the dynamic aperture is large enough to allow off-axis injection. The alignment and stability tolerances, though challenging, are achievable. A ring with all
SLAC is developing a long-range plan to transfer the evolving scientific programs at SSRL from th... more SLAC is developing a long-range plan to transfer the evolving scientific programs at SSRL from the SPEAR3 light source to a much higher performing photon source. One of the possibilities is a new PEP-X 4.5 GeV storage ring that would be housed in the 2.2 km PEP-II tunnel [1, 2]. The PEP-X is designed to produce photon beams having brightness near 10 22 (ph/s/mm 2 /mrad 2 /0.1 % BW) at 10 keV with 3.5 m undulator at beam current of 1.5 A. This report presents an overview of the PEP-X baseline lattice design and describes the lattice optimization procedures in order to maximize the beam dynamic aperture [3]. The complete report of PEP-X baseline design is published in SLAC report [4]. Keywords: light source, accelerator, brightness, emittance
There are several preferred methods for analyzing chemical and biochemical reactions with an elec... more There are several preferred methods for analyzing chemical and biochemical reactions with an electrospray mass spectrometer. The hardware required for analyzing enzymes includes, an electrospray ionization inlet, mass spectrometer, at least two syringes, at least one pushing ram, a mixing device, and monitoring equipment. The pushing ram includes a platen for pushing the plunger of at least one syringe. The platen is preferably actuated by rotation of a stepper motor, or the like. The rotation of the stepper motor is preferably microprocessor controlled. The output of each syringe is connected to the mixing device which mixes the reactant in each syringe and starts a chemical reaction. The output of the mixing device is connected to the input orifice of the electrospray ionization inlet with a reaction tube having a specific volume. The mixed reaction solution is input through the input orifice of the electrospray ionization inlet. The volatile molecules of the solution are removed ...
SLAC expertise in designing and operating high current storage rings and the availability of the ... more SLAC expertise in designing and operating high current storage rings and the availability of the 2.2-km PEP-II tunnel present an opportunity for building a next generation light source - PEP-X - that would replace the SPEAR3 storage ring in the future. The PEP-X 'baseline' design, with 164 pm-rad emittance at 4.5 GeV beam energy and a current of 1.5 A, was completed in 2010. As a next step, a so-called 'ultimate' PEP-X lattice, reducing the emittance to 11 pm-rad at zero current, has been designed. This emittance approaches the diffraction limited photon emittance for multi-keV photons, providing near maximum photon brightness and high coherence. It is achieved by using 7-bend achromat cells in the ring arcs and a 90-m damping wiggler in one of the 6 long straight sections. Details of the lattice design, dynamic aperture, and calculations of the intra-beam scattering effect and Touschek lifetime at a nominal 0.2 A current are presented. Accelerator-based light source...
The SPEAR2 accelerator system originally had 3 RF stations (2 for storage ring, 1 Booster) operat... more The SPEAR2 accelerator system originally had 3 RF stations (2 for storage ring, 1 Booster) operating at 358.5 MHz. SPEAR3 now operates at 476.3 MHz with the PEPII type RF system, while the Booster RF frequency remains unchanged. For top-off operation, the Booster injects single 3.0 GeV electron bunches into SPEAR3 at 10 Hz every 5 minutes to replenish lost charge. Due to the frequency mismatch between SPEAR3 and the Booster, only one SPEAR3 bucket can injected per shot limiting injection rate and overall system flexibility. The aging high-power RF subsystems of the Booster pose a reliability issue as well. In order to remove these constraints, studies are underway to replace the Booster RF system using the PEP-II type RF system as a baseline. The new Booster RF system will be tuned to 475.036 MHz, and phase-locked to the SPEAR3 RF system. The project calls for ramping the Booster cavity gap voltage to 0.80 MV at 10 Hz, each with a 40 ms acceleration interval. With very low beam load...
A global orbit feedback system has been installed on SPEAR to help stabilize the position of the ... more A global orbit feedback system has been installed on SPEAR to help stabilize the position of the photon beams. The orbit control algorithms depend on either harmonic reconstruction of the orbit or eigenvector decomposition. The orbit motion is corrected by dipole corrector kicks determined from the inverse corrector-to-bpm response matrix. This paper outlines features of these control algorithms as applied to SPEAR.
We review the present developments in the design of ultra-low emittance storage ring light source... more We review the present developments in the design of ultra-low emittance storage ring light sources those having emittances approaching the diffraction limit for multi-keV X-ray production and the associated design challenges. An overview is presented of the design approaches for these 4 generation storage ring (4GSR) light sources now in construction or being studied for near-term implementation, together with concepts for future rings that would operate with emittances at or below the diffraction limit for 1-Å (12-keV).
34 Vol. 32, No. 2, 2019, Synchrotron radiation newS While the Advance Photon Source (APS) continu... more 34 Vol. 32, No. 2, 2019, Synchrotron radiation newS While the Advance Photon Source (APS) continues with outstanding accelerator performance and supporting a productive research program, the APS is looking to the future. To stay at the leading edge of hard X-ray synchrotron light sources, the APS is developing the designs for a low-emittance multibend achromat (MBA) storage ring to replace the existing storage ring, and for a number of state-of-the-art X-ray beamlines to exploit the high transverse photon coherence of the new source. In December 2018, the APS Upgrade Project (APS-U) received the good news that the U.S. Department of Energy’s Office of Science approved the project’s preliminary design and baseline scope, cost ($815M, including labor and contingency), and schedule. The replacement of the storage ring is slated to start in 2022 with a dark time plus accelerator commissioning period of approximately one year. The MBA, a so-called fourth-generation storage ring (4GSR), will provide from two to three orders of magnitude higher spectral brightness and transverse coherence than the existing storage ring lattice. The APS-U scope include:
This report summaries the workshop on accelerator R&D for ultimate storage ring, held in Huairou,... more This report summaries the workshop on accelerator R&D for ultimate storage ring, held in Huairou, Beijing, Oct. 30 to Nov. 1, 2012.
SLAC National Accelerator Laboratory is studying an option of building a high brightness synchrot... more SLAC National Accelerator Laboratory is studying an option of building a high brightness synchrotron light source machine, PEP-X, in the existing PEP-II tunnel [1, 2]. By replacing 6 arcs of FODO cells of PEPII High Energy Ring (HER) with two arcs of DBA and four arcs of TME and installation of 89.3 m long damping wiggler an ultra low beam emittance of 0.14 nm-rad (including intra-beam scattering) at 4.5 GeV is achieved. In this paper we study the possibility to further reduce the beam emittance by releasing the constraint of the dispersion free in the DBA straight. The QBA (Quadruple Bend Achromat) cell is used to replace the DBA. The ratio of outer and inner bending angle is optimized. The dispersion function in the non-dispersion straight is controlled to compromise with lower emittance and beam size at the dispersion straight. An undulator of period length 23 mm, maximum magnetic field of 1.053 T, and total periods of 150 is used to put in the 30 straights to simulate the effect...
A lattice for the PEP-X ultimate storage ring light source, having 11 pm-rad natural emittance at... more A lattice for the PEP-X ultimate storage ring light source, having 11 pm-rad natural emittance at a beam energy of 4.5 GeV at zero current, using 90 m of damping wiggler and fitting into the existing 2.2-km PEP-II tunnel, has been recently designed. Such a low emittance lattice requires very strong sextupoles for chromaticity correction, which in turn introduce strong non-linear field effects that limit the beam dynamic aperture. In order to maximize the dynamic aperture we choose the cell phases to cancel the third and fourth order geometric resonances in each 8-cell arc. Four families of chromatic sextupoles and six families of geometric (or harmonic) sextupoles are added to correct the chromatic and amplitude-dependent tunes. To find the best settings of the ten sextupole families, we use a Multi-Objective Genetic Optimizer employing elegant to optimize the beam lifetime and dynamic aperture simultaneously. Then we evaluate dynamic aperture reduction caused by magnetic field mult...
The SPEAR3 accelerator upgrade opened up two 7.6m racetrack straights in the magnet lattice. In o... more The SPEAR3 accelerator upgrade opened up two 7.6m racetrack straights in the magnet lattice. In one of these straights, we recently added a magnetic chicane to separate two insertion device (ID) beam lines by 10mrad. A quadrupole triplet in the center creates a ''double focus'' optics with {beta}y = 1.6m at the middle of each ID, hence the term ''double-waist chicane''. The new optics also reduced {beta}y in the four matching straights adjacent to the racetrack straights to 2.5m. In this paper, we outline design features of the optics and physical implementation of the lattice.
SPEAR3 has a large cross-section copper vacuum chamber, mode-damped RF cavities and mostly low-im... more SPEAR3 has a large cross-section copper vacuum chamber, mode-damped RF cavities and mostly low-impedance insertion devices. As a result, the beam is nearly passivestable for 280-bunch beam currents up to 500 mA when the background gas pressure is low. In the future, more small-gap insertion devices will be installed and plans are underway to implement crabbing systems for short-pulse production. These requirements drive the need for a transverse bunch-by-bunch feedback system (BxB). In this paper we present plans for stripline kickers.
Since its 2003 construction, the SPEAR3 synchrotron light source at SLAC has continuously improve... more Since its 2003 construction, the SPEAR3 synchrotron light source at SLAC has continuously improved its performance by raising beam current, top-off injection, small alpha and smaller emittance. This makes SPEAR3 one of the most productive light sources in the world. Now to further enhance the operation of SPEAR3, we are looking into the possibility of converting SPEAR3 to a multi-bend achromat storage ring within its site constraint.
We describe the design of an FEL Amplifier Test Experiment (FATE) 1 to demonstrate the superradia... more We describe the design of an FEL Amplifier Test Experiment (FATE) 1 to demonstrate the superradiant short bunch regime of a Free Electron Laser in the 1-3 m wavelength range starting from noise. The relevance to the LCLS X-ray FEL [1] proposal is discussed and numerical simulations are shown. It is numerically demonstrated for the first time with the 2-D code GINGER, that clean-up of noise in the superradiant regime occurs even at low power levels.
Adaptation technologies may require new hardware or different implementation approaches ('softwar... more Adaptation technologies may require new hardware or different implementation approaches ('software'). Five main areas of adaptation technology application are: regional and local climate modeling and early warning, coastal zone management, water resources, agriculture and public health. Table 2 provides an indicative list of adaptation technologies in these five areas. Technological progress can take place through: scientific innovation and invention, the adoption and adaptation of pre-existing but new-to-the-market technologies, and the diffusion of technologies. Enormous gaps remain, especially in the case of the least developed countries. Technology development and transfer can be either accelerated or slowed depending on market conditions, fiscal and regulatory policies, availability of finance, access to information, the legal and institutional framework, human resource capacities, and the condition of infrastructure. Each country needs to conduct its own assessment of the most important domestic barriers to clean technology development and transfer. In addition, there are also barriers relating to international trade and associated rules, for example, with respect to intellectual property rights. Financial constraints are most often cited as a barrier to adoption of environmentally sound technologies in those non-Annex I countries which have conducted technology needs assessments. Capital shortages and high capital costs are still commonplace in many developing countries. Underdeveloped financial sectors and inhospitable investment environments are key reasons. These constraints may be tightened by the current global financial crisis. Small domestic markets for low-carbon technologies are another oft-mentioned barrier to technology adoption. Limited information about the availability of technologies and technology suppliers was another frequently cited barrier to technology acquisition. However, the biggest obstacle is that existing technologies are too expensive, making the resulting services unaffordable for the bulk of the populations of non-Annex I countries. Government policies can support or hinder low-carbon energy technology development and transfer. Supportive legal and regulatory frameworks may include energy-efficiency codes for buildings, fuel efficiency standards for motor vehicles and mandates for renewable energy use. Given cost disadvantages still faced by many non-conventional energy sources, government subsidies, feed-in tariffs and other support can facilitate adoption, but these may require international support. Rapid adoption of alternative energy technologies is hindered by subsidized conventional energy prices. However, removal of the subsidies without an increase in income or the availability of other affordable energy services could be both inequitable and socially unacceptable. IGCC 1 commercialization Solid oxide fuel cells Cleaner coal plants Hydrogen (H 2) co-production from coal/biomass Hydrogen Integrated stationary fuel cell systems Demonstration H 2 production from renewable sources Low cost H 2 storage and delivery. H 2 from renewable sources. Renewable H 2powered fuel cell vehicles H 2 and electric economy Renewable energy Lower cost wind power Demonstration cellulosic ethanol Photovoltaic (PV) clad buildings. Cost-competitive solar PV First-generation bio-refinery Low-wind speed turbines Advanced bio-refineries Cellulosic biofuels Community-scale solar systems Water photolysis Energy storage options Widespread renewable energy utilisation Genetically engineered biomass Biologically inspired energy and fuels Nuclear fission & fusion Advanced reactor and fuel cycle technology Generation IV nuclear plants. Fusion plant demonstration Advanced concepts for waste reduction. Fusion power plants Reforestation Soil conservation Sequestration decision support tools. Bio-based and recycled products Biological sequestration Carbon and CO 2 based products and materials Marine sequestration Effective dilution of directly injected CO 2 Carbonate dissolution/alkaline addition Safe long-term marine storage EMISSION REDUCTION OF OTHER GHGs Methane from energy production and waste Bioreactor landfill technology New drilling techniques for recovery of coal-bed methane Advanced landfill gas utilization. Ventilation-air methane technologies Integrated waste management systems Methane and N 2 O from agriculture Anaerobic digesters for heat and electricity production Utilisation of soil microbial processes Zero-emission agriculture High global warming potential gases Advanced refrigeration technologies. Advanced aluminium smelting processes Alternative refrigeration fluids Solid-state refrigeration and air conditioning systems N 2 O from combustion Catalytic reduction of N 2 O in nitric oxide plants Catalysts that reduce N 2 O to elemental nitrogen in diesel engines Advanced vehicles and noncarbon based fuels Require a well-specified research objective xviii 1 I.
Over the past year, we have worked out a baseline design for PEP-X, as an ultra-low emittance sto... more Over the past year, we have worked out a baseline design for PEP-X, as an ultra-low emittance storage ring that could reside in the existing 2.2-km PEP-II tunnel. The design features a hybrid lattice with double bend achromat cells in two arcs and theoretical minimum emittance cells in the remaining four arcs. Damping wigglers reduce the horizontal emittance to 86 pm-rad at zero current for a 4.5 GeV electron beam. At a design current of 1.5 A, the horizontal emittance increases, due to intra-beam scattering, to 164 pm-rad when the vertical emittance is maintained at a diffraction limited 8 pm-rad. The baseline design will produce photon beams achieving a brightness of 10²² (ph/s/mm²/mrad²/0.1% BW) at 10 keV in a 3.5-m conventional planar undulator. Our study shows that an optimized lattice has adequate dynamic aperture, while accommodating a conventional off-axis injection system. In this paper, we will present the study of the lattice properties, nonlinear dynamics, intra-beam sca...
With the recent success in commissioning of MAX IV, the multi-bend achromat (MBA) lattice has beg... more With the recent success in commissioning of MAX IV, the multi-bend achromat (MBA) lattice has begun to deliver on its promise to usher in a new generation of higher-brightness synchrotron light sources. In this paper, we begin by reviewing the challenges, recent success, and lessons learned of the MAX-IV project. Drawing on these lessons, we then describe the physics challenges in even more ambitious rings and how these can be met. In addition, we touch on engineering issues and choices that are tightly linked with the physics design.
We completed a design of PEP-X [1] as a highbrightness light source that could reside in the exis... more We completed a design of PEP-X [1] as a highbrightness light source that could reside in the existing 2.2km PEP-II tunnel. The design features a hybrid lattice with double bend achromat (DBA) cells in two arcs and theoretical minimum emittance (TME)cells in the remaining four arcs. The baseline design will produce photon beams achieving a brightness of 10 22 (ph/s/mm 2 /mrad 2 /0.1% BW) at 10 keV in a 3.5-m conventional planar undulator. Our study shows that an optimized lattice has adequate dynamic aperture, while accommodating a conventional offaxis injection system. In the paper, we will summarize the results of the study, including the lattice properties, nonlinear dynamics, intra-beam scattering and Touschek lifetime, and collective instabilities. This future light source has a potential to reach high coherence in both transverse dimensions for multi-keV photons and to lase partially in a very long undulator at soft x-ray wavelengths. Achieving these features would make this st...
We have designed an “ultimate” storage ring for the PEP-X light source that achieves the diffract... more We have designed an “ultimate” storage ring for the PEP-X light source that achieves the diffraction limited emittances (at 1.5 ˚A) of 12 pm-rad in both horizontal and vertical planes with a 4.5-GeV beam. These emittances include the contribution of intrabeam scattering at a nominal current of 200 mA in 3300 bunches. This quality beam in conjunction with a conventional 4-m undulator in a straight section can generate synchrotron radiation having a spectral brightness above 10 22 [photons/s/mm 2 /mrad 2 /0.1% BW] at a 10 keV photon energy. The high coherence at the diffraction limit makes PEP-X competitive with 4th generation light sources based on an energy recovery linac. In addition, the beam lifetime is several hours and the dynamic aperture is large enough to allow off-axis injection. The alignment and stability tolerances, though challenging, are achievable. A ring with all
SLAC is developing a long-range plan to transfer the evolving scientific programs at SSRL from th... more SLAC is developing a long-range plan to transfer the evolving scientific programs at SSRL from the SPEAR3 light source to a much higher performing photon source. One of the possibilities is a new PEP-X 4.5 GeV storage ring that would be housed in the 2.2 km PEP-II tunnel [1, 2]. The PEP-X is designed to produce photon beams having brightness near 10 22 (ph/s/mm 2 /mrad 2 /0.1 % BW) at 10 keV with 3.5 m undulator at beam current of 1.5 A. This report presents an overview of the PEP-X baseline lattice design and describes the lattice optimization procedures in order to maximize the beam dynamic aperture [3]. The complete report of PEP-X baseline design is published in SLAC report [4]. Keywords: light source, accelerator, brightness, emittance
There are several preferred methods for analyzing chemical and biochemical reactions with an elec... more There are several preferred methods for analyzing chemical and biochemical reactions with an electrospray mass spectrometer. The hardware required for analyzing enzymes includes, an electrospray ionization inlet, mass spectrometer, at least two syringes, at least one pushing ram, a mixing device, and monitoring equipment. The pushing ram includes a platen for pushing the plunger of at least one syringe. The platen is preferably actuated by rotation of a stepper motor, or the like. The rotation of the stepper motor is preferably microprocessor controlled. The output of each syringe is connected to the mixing device which mixes the reactant in each syringe and starts a chemical reaction. The output of the mixing device is connected to the input orifice of the electrospray ionization inlet with a reaction tube having a specific volume. The mixed reaction solution is input through the input orifice of the electrospray ionization inlet. The volatile molecules of the solution are removed ...
SLAC expertise in designing and operating high current storage rings and the availability of the ... more SLAC expertise in designing and operating high current storage rings and the availability of the 2.2-km PEP-II tunnel present an opportunity for building a next generation light source - PEP-X - that would replace the SPEAR3 storage ring in the future. The PEP-X 'baseline' design, with 164 pm-rad emittance at 4.5 GeV beam energy and a current of 1.5 A, was completed in 2010. As a next step, a so-called 'ultimate' PEP-X lattice, reducing the emittance to 11 pm-rad at zero current, has been designed. This emittance approaches the diffraction limited photon emittance for multi-keV photons, providing near maximum photon brightness and high coherence. It is achieved by using 7-bend achromat cells in the ring arcs and a 90-m damping wiggler in one of the 6 long straight sections. Details of the lattice design, dynamic aperture, and calculations of the intra-beam scattering effect and Touschek lifetime at a nominal 0.2 A current are presented. Accelerator-based light source...
The SPEAR2 accelerator system originally had 3 RF stations (2 for storage ring, 1 Booster) operat... more The SPEAR2 accelerator system originally had 3 RF stations (2 for storage ring, 1 Booster) operating at 358.5 MHz. SPEAR3 now operates at 476.3 MHz with the PEPII type RF system, while the Booster RF frequency remains unchanged. For top-off operation, the Booster injects single 3.0 GeV electron bunches into SPEAR3 at 10 Hz every 5 minutes to replenish lost charge. Due to the frequency mismatch between SPEAR3 and the Booster, only one SPEAR3 bucket can injected per shot limiting injection rate and overall system flexibility. The aging high-power RF subsystems of the Booster pose a reliability issue as well. In order to remove these constraints, studies are underway to replace the Booster RF system using the PEP-II type RF system as a baseline. The new Booster RF system will be tuned to 475.036 MHz, and phase-locked to the SPEAR3 RF system. The project calls for ramping the Booster cavity gap voltage to 0.80 MV at 10 Hz, each with a 40 ms acceleration interval. With very low beam load...
A global orbit feedback system has been installed on SPEAR to help stabilize the position of the ... more A global orbit feedback system has been installed on SPEAR to help stabilize the position of the photon beams. The orbit control algorithms depend on either harmonic reconstruction of the orbit or eigenvector decomposition. The orbit motion is corrected by dipole corrector kicks determined from the inverse corrector-to-bpm response matrix. This paper outlines features of these control algorithms as applied to SPEAR.
We review the present developments in the design of ultra-low emittance storage ring light source... more We review the present developments in the design of ultra-low emittance storage ring light sources those having emittances approaching the diffraction limit for multi-keV X-ray production and the associated design challenges. An overview is presented of the design approaches for these 4 generation storage ring (4GSR) light sources now in construction or being studied for near-term implementation, together with concepts for future rings that would operate with emittances at or below the diffraction limit for 1-Å (12-keV).
34 Vol. 32, No. 2, 2019, Synchrotron radiation newS While the Advance Photon Source (APS) continu... more 34 Vol. 32, No. 2, 2019, Synchrotron radiation newS While the Advance Photon Source (APS) continues with outstanding accelerator performance and supporting a productive research program, the APS is looking to the future. To stay at the leading edge of hard X-ray synchrotron light sources, the APS is developing the designs for a low-emittance multibend achromat (MBA) storage ring to replace the existing storage ring, and for a number of state-of-the-art X-ray beamlines to exploit the high transverse photon coherence of the new source. In December 2018, the APS Upgrade Project (APS-U) received the good news that the U.S. Department of Energy’s Office of Science approved the project’s preliminary design and baseline scope, cost ($815M, including labor and contingency), and schedule. The replacement of the storage ring is slated to start in 2022 with a dark time plus accelerator commissioning period of approximately one year. The MBA, a so-called fourth-generation storage ring (4GSR), will provide from two to three orders of magnitude higher spectral brightness and transverse coherence than the existing storage ring lattice. The APS-U scope include:
This report summaries the workshop on accelerator R&D for ultimate storage ring, held in Huairou,... more This report summaries the workshop on accelerator R&D for ultimate storage ring, held in Huairou, Beijing, Oct. 30 to Nov. 1, 2012.
Uploads
Papers by Robert Hettel