The SNS Cryogenic Control System: Experiences in Collaboration

The cryogenic system for the Spallation Neutron Source (SNS) is designed by Jefferson Laboratory (JLab) personnel and is based on the existing JLab facility. Our task is to use the JLab control system design [2] as much as practical while remaining consistent with SNS control system standards. Some aspects of the systems are very similar, including equipment to be controlled, the need for PID loops and automatic sequences, and the use of EPICS. There are differences in device naming, system hardware, and software tools. The cryogenic system is the first SNS system to be developed using SNS standards. This paper reports on our experiences in integrating the new and the old.Comment: 3 page

Towards distributed architecture for collaborative cloud services in community networks

Internet and communication technologies have lowered the costs for communities to collaborate, leading to new services like user-generated content and social computing, and through collaboration, collectively built infrastructures like community networks have also emerged. Community networks get formed when individuals and local organisations from a geographic area team up to create and run a community-owned IP network to satisfy the community’s demand for ICT, such as facilitating Internet access and providing services of local interest. The consolidation of today’s cloud technologies offers now the possibility of collectively built community clouds, building upon user-generated content and user-provided networks towards an ecosystem of cloud services. To address the limitation and enhance utility of community networks, we propose a collaborative distributed architecture for building a community cloud system that employs resources contributed by the members of the community network for provisioning infrastructure and software services. Such architecture needs to be tailored to the specific social, economic and technical characteristics of the community networks for community clouds to be successful and sustainable. By real deployments of clouds in community networks and evaluation of application performance, we show that community clouds are feasible. Our result may encourage collaborative innovative cloud-based services made possible with the resources of a community.Peer ReviewedPostprint (author’s final draft

Control system integration

This lecture begins with a definition of an accelerator control system, and then reviews the control system architectures that have been deployed at the larger accelerator facilities. This discussion naturally leads to identification of the major subsystems and their interfaces. We shall explore general strategies for integrating intelligent devices and signal processing subsystems based on gate arrays and programmable DSPs. The following topics will also be covered: physical packaging; timing and synchronization; local and global communication technologies; interfacing to machine protection systems; remote debugging; configuration management and source code control; and integration of commercial software tools. Several practical realizations will be presented

Synchronous LoRa mesh network to monitor processes in underground infrastructure

Collecting precise real-time information on urban drainage system performance is essential to identify, predict, and manage critical loading situations, such as urban flash floods and sewer overflows. Although emerging low-power wireless communication techniques allow efficient data transfers with great above-ground performance, for underground or indoor applications in a large coverage range are difficult to achieve due to physical and topological limitations, particularly in dense urban areas. In this paper, we first discuss the range limitations of the LoRaWAN standard based on a systematic evaluation of a long-term operation of a sensor network monitoring in-sewer process dynamics. Analyses reveal an-on average-five-fold higher data packet loss for sub-surface nodes, which steadily grows with increasing distance to the gateway. Second, we present a novel LPWAN concept based on the LoRa technology that enhances transmission reliability, efficiency, and flexibility in range-critical situations through meshed multi-hop routing and ensures a precise time-synchronization through optional GPS or DCF77 long-wave time signaling. Third, we illustrate the usefulness of the newly developed concept by evaluating the radio transmission performance for two independent full-scale field tests. Test results show that the synchronous LoRa mesh network approach clearly outperforms the standard LoRaWAN technique with regard to the reliability of packet delivery when transmitting from range-critical locations. Hence, the approach is expected to generally ease data collection from difficult-to-access locations such as underground areas

Design and Development of EPICS Based RF Conditioning System for the High Power RF Components of Charged Particle Accelerators

Charged particle accelerators use various vacuum windows on their accelerating RF cavities to pass very high RF power through for the acceleration of particles. The accelerating cavities and the windows should be cleaned, baked and fully RF conditioned to eliminate poor vacuum caused by outgassing and other contamination. The linear accelerator (Linac) in the Spallation Neutron Source (SNS) contains various accelerating cavity structures and RF conditioning of their high power vacuum windows is necessary for present work as well as future upgrade and development. An example is the coaxial fundamental power coupler (FPC) with an annular alumina ceramic window for each of the 81 superconducting RF cavities in the SNS Linac. The FPC’s need to be tested up to 650 kW peak in traveling wave and 2.6 MW in standing wave in 1.3 microsecond 60 pulses per second RF. 805 MHz, 550-kW klystrons (700 kW maximum) are the main power source of the superconducting Linac and the conditioning power source of the FPC’s. The conditioning process has to be controlled very carefully not to damage the window; with the high power RF the initial vacuum is unpredictable and any unsafe vacuum level can damage the high quality ceramic windows. In this thesis, an Experimental Physics and Industrial Control System (EPICS) controlled RF conditioning system for the SNS RF Test Facility (RFTF) has been presented. Various RF and control instruments are integrated through the EPICS system on Linux platform to measure and to control the vacuum and the RF power while monitoring electron emission and unwanted arcing during the conditioning. Monitoring arcing at the window and flow and temperature of cooling water in high power RF load and ceramic window is necessary to interlock the RF not to have any kind of undesirable operation condition. The interlock system has been designed by using the Programmable Logic Controller (PLC) and an RF switch with microseconds response time. Usually the whole conditioning process takes several days, so it is necessary to get the flexibility to control, monitor, and archive the system operation remotely along with good upgradeability. To get these advantages in EPICS, VXI/VME based Input and Output Controller (IOC)s are used for controlling and monitoring the RF conditioning system. This thesis summarizes all the hardware and software design strategies, provides the results obtained so far at room temperature and describes the future research scope