Jerzy Nogiec

A new facility to test superconducting accelerator magnets

Future high energy accelerators such as the Large Hadron Collider require accelerator magnets with the highest possible fields. For NbTi conductor magnets, this means operating at superfluid helium temperatures in the range of 1.8-1.9 K. As part of Fermilabs superconducting magnet R&D program, we have built a facility to test magnets in a vertical dewar of superfluid liquid helium. The dewar is designed for magnets up to 4 m length and 620 mm diameter, with a temperature range of 1.8 K to 4.4 K and 1 atmosphere helium. The power system consists of 10 kA and 8.8 kA power supplies operating in parallel, with a bus work and an extraction circuit that can accommodate up a 18 kA excitation current. A description of the facility as well as operational experience from the first magnet tests are presented.

A Configurable Component-Based Software System for Magnetic Field Measurements

A new software system to test accelerator magnets has been developed at Fermilab. The magnetic measurement technique involved employs a single stretched wire to measure alignment parameters and magnetic field strength. The software for the system is built on top of a flexible component-based framework, which allows for easy reconfiguration and runtime modification. Various user interface, data acquisition, analysis, and data persistence components can be configured to form different measurement systems that are tailored to specific requirements (e.g., involving magnet type or test stand). The system can also be configured with various measurement sequences or tests, each of them controlled by a dedicated script. It is capable of working interactively as well as executing a pre-selected sequence of tests. Each test can be parameterized to fit the specific magnet type or test stand requirements. The system has been designed with portability in mind and is capable of working on various platforms, such as Linux, Solaris, and Windows. It can be configured to use a local data acquisition subsystem or a remote data acquisition computer, such as a VME processor running VxWorks. All hardware-oriented components have been developed with a simulation option that allows for running and testing measurements in the absence of data acquisition hardware

Mu2e Transport Solenoid Prototype Tests Results

The Fermilab Mu2e experiment has been developed to search for evidence of charged lepton flavor violation through the direct conversion of muons into electrons. The transport solenoid is an s-shaped magnet that guides the muons from the source to the stopping target. It consists of 52 superconducting coils arranged in 27 coil modules. A full-size prototype coil module, with all the features of a typical module of the full assembly, was successfully manufactured by a collaboration between INFN-Genoa and Fermilab. The prototype contains two coils that can be powered independently. To validate the design, the magnet went through an extensive test campaign. Warm tests included magnetic measurements with a vibrating stretched wire and electrical and dimensional checks. The cold performance was evaluated by a series of power tests and temperature dependence and minimum quench energy studies.

Field quality measurements of the LQXB inner triplet quadrupoles for LHC

As a part of the USLHC program, Fermilab is building half of the inner triplet quadrupole magnets for the LHC. Two identical quadrupoles (MQXB) with a dipole corrector between them in a single cryogenic unit (LQXB) comprise the Q2 optical element of the final focus triplets in the interaction regions. The 5.5 m long MQXB have a 70 mm aperture and operate in superfluid helium at 1.9 K with a peak field gradient of 215 T/m. Manufacturing of the 18 magnets is in an advanced stage. A program of magnetic field quality measurements of the magnets is performed at room temperature during magnet fabrication as well as at superfluid helium temperature during the cold qualification of each magnet. Results of the measurements are summarized in this paper.

A quench management system for testing superconducting magnets

A quench management system has been developed for the Fermilab Magnet Test Facility as part of the overall data acquisition and control system for testing superconducting accelerator magnets. The quench management system accepts a standard set of quench input signals such as magnet voltages and current, safety interlocks, and power supply status, which are multiplexed from several independent test stands. It also issues a standard set of output control signals that are used to activate the dump, the quench protection heater power supplies, and to control the magnet ramp down in the event of a quench. Triggers generated by the quench management system are used to save the logged quench data from both the fast and slow data acquisition instrumentation. The hardware architecture of the quench management system will be discussed along with analog quench detection, digital quench detection, quench logic, and the user interface for configuring and controlling this system.

EMS: A framework for data acquisition and analysis

The Extensible Measurement System (EMS) is a universal Java framework for building data analysis and test systems. The objective of the EMS project is to replace a multitude of different existing systems with a single expandable system, capable of accommodating various test and analysis scenarios and varying algorithms. The EMS framework is based on component technology, graphical assembly of systems, introspection and flexibility to accommodate various data processing and data acquisition components. Core system components, common to many application domains, have been identified and designed together with the domain-specific components for the measurement of accelerator magnets. The EMS employs several modern technologies and the result is a highly portable, configurable, and potentially distributed system, with the capability of parallel signal data processing, parameterized test scripting, and run-time reconfiguration.

Maximize System Reliability for Long Lasting and Continuous Applications

In this paper, we use software rejuvenation as a preventive and proactive fault-tolerance technique to maximize the level of reliability for continuous and safety critical systems. We take both transient faults caused by software aging effects and network transmission faults into consideration and mathematically analyze the optimal software rejuvenation period that maximizes system’s reliability. The theoretical result is verified through empirical studies.

Electrical and Quench Performance of the First MICE Coupling Coil

The first MICE Coupling Coil has been tested in a conduction-cooled environment in the new Solenoid Test Facility at Fermilab. We present an overview of the power and quench protection scheme, and report on the electrical and quench performance results obtained during cold power tests of the magnet.

Prototype Conduction Cooled Capture Solenoid Test Design and Plans

Large aperture superconducting solenoid magnets are needed for the production and capture of pions, which decay to create intense muon beams in future experiments to search for direct muon to electron conversion. The COMET experiment in Japan and the Mu2e experiment in the U.S. are jointly conducting research into the design of capture solenoid coils made from aluminum-stabilized NbTi superconductor that is cooled by conduction to a supply of liquid helium. A prototype coil of 1.3-m inner diameter, having four layers of eight turns each, has been wound with pure aluminum interlayer fins for the conduction cooling. The test coil includes two types of welded splices, two film heaters for quench studies, and extensive instrumentation to evaluate strain, temperature profiles, and coil voltages. Details of the cryogenic conduction cooling scheme, test systems design, and test program plans will be discussed.

Magnetic and Thermal Performance of a Conduction-Cooled Splittable Quadrupole

A superconducting quadrupole magnet with splittable yoke has been designed for use in ILC Main Linac (ML) cryomodules. The splittable yoke allows assembly around the beam pipe, to avoid potential contamination of the superconducting RF cavities. The magnet is cooled by conduction and covers the full range of required ML field gradients. A critical requirement is stability of the magnetic center, at the level of 5 μm, for a 20% variation of the operating field. We report here the results of thermal, quench, and magnetic performance tests of a prototype splittable quadrupole, that were made up to the maximum design operating gradient in a conduction-cooled test cryostat.