AC Loss Measurement in NbSn Coil for a New Fast Switching-field MR Concept Magnet.

The ability to perform magnetic resonance (MR) imaging or spectroscopy at significantly different magnetic field strengths during scanning holds great potential for expanding the range of contrast parameter options and obtaining high "superthermal" spin polarization for increased signal-to-noise ratio (SNR) or measuring certain spins at what would otherwise be impractically high RF frequencies. Enabling measurements at multiple field strengths heretofore has required either rapidly altering the strength of a resistive magnet with pulsed currents or shuttling the specimen between two field regions. We propose a novel approach to switching-field MR that we expect to be practical for live animal and ultimately human imaging.

Self-Protection Characteristic Comparison between No-Insulation, Metal-as-Insulation, and Surface-Shunted-Metal-as-Insulation REBCO coils.

The metal tape co-winding or a metal-as-insulation (MI) winding method is an excellent way to improve the mechanical properties and reduce the average current density, thereby decreasing the stress in high-field REBCO magnet without completely losing the benefits of the no-insulation (NI) winding method. However, the MI winding increases the resistance between turns, which is known as characteristic resistance. The increased characteristic resistance can reduce the bypass current during abnormal transition situation, such as quench, which may not be desirable from a magnet protection point of view.

First-Cut Design of a Benchtop Cryogen-Free 23.5-T/25-mm Magnet for 1-GHz Microcoil NMR.

As a preliminary work, we have completed a 12.5-mm-cold-bore high-temperature superconducting (HTS) REBCO magnet prototype and successfully operated it up to 25 T at 10 K cooled by a cryocooler only, without liquid helium. In this paper we present the first-cut design of a cryogen-free all-REBCO 23.

Conceptual Design of a Portable, Solid-Nitrogen-Cooled 0.5-T/560-mm Point-of-Care MRI Magnet.

We describe the conceptual design of a portable, liquid-helium-free, all-REBCO, 0.5-T/560-mm point-of-care magnetic resonance imaging (MRI) magnet. It is free from an external power supply and a refrigeration system during operation.

Analysis techniques for blob properties from gas puff imaging data.

Filamentary structures, also known as blobs, are a prominent feature of turbulence and transport at the edge of magnetically confined plasmas. They cause cross-field particle and energy transport and are, therefore, of interest in tokamak physics and, more generally, nuclear fusion research. Several experimental techniques have been developed to study their properties.

Gas puff imaging on the TCV tokamak.

We present the design and operation of a suite of Gas Puff Imaging (GPI) diagnostic systems installed on the Tokamak à Configuration Variable (TCV) for the study of turbulence in the plasma edge and Scrape-Off-Layer (SOL). These systems provide the unique ability to simultaneously collect poloidal 2D images of plasma dynamics at the outboard midplane, around the X-point, in both the High-Field Side (HFS) and Low-Field Side (LFS) SOL, and in the divertor region. We describe and characterize an innovative control system for deuterium and helium gas injection, which is becoming the default standard for the other gas injections at TCV.

A Cryogen-Free 25-T REBCO Magnet with the Extreme-No-Insulation Winding Technique.

We present the operation result of a cryogen-free 23.5 T/φ12.5 mm-cold-bore magnet prototype composed of a stack of 12 no-insulation (NI) REBCO single pancake coils-ten middle coils of 6-mm wide and two end coils of 8-mm wide tape-forming 6 double pancake (DP) coils with inner joints.

Correction to: Study of the Effect of Reflections on High-Power, 110-GHz Pulsed Gyrotron Operation.

[This corrects the article PMC8291730.].

Study of the Effect of Reflections on High-Power, 110 GHz Pulsed Gyrotron Operation.

The effect of reflection is studied experimentally and theoretically on a high-power 110 GHz gyrotron operating in the TE mode in 3 s pulses at 96 kV, 40 A. The experimental setup allows variation of the reflected power from 0 to 33 % over a range of gyrotron operating conditions. The phase of the reflection is varied by translating the reflector along the axis.

Experimental and Numerical Studies on a Method to Mitigate Screening Current-Induced Field for No-Insulation REBCO Coils.

We present experimental and numerical studies on a method to mitigate screening current-induced field (SCF) for NI REBCO coil. The SCF is the major field error to incorporate a REBCO insert for a high field LTS/HTS magnet. The field-shaking technique is going to be used to mitigate the SCF of 800-MHz REBCO insert magnet (H800) for MIT 1.

HTS Shim Coils Energized by a Flux Pump for the MIT 1.3-GHz LTS/HTS NMR magnet: Design, Construction, and Results of a Proof-of-Concept Prototype.

In this paper we present design, construction, and preliminary results of a proof-of-concept prototype of high-temperature superconductor (HTS) shim coils operated at 77 K and energized, for the first time among all shim coils, by a flux pump, here called digital flux injector (DFI). Although the prototype shims were wound with 2-mm wide REBCO tape, and DFI with Bi2223 and REBCO tapes, the HTS Z1 and Z2 shims to be installed in the MIT 1.3-GHz LTS/HTS NMR magnet (1.

A Tabletop Persistent-Mode, Liquid-Helium-Free, 1.5-T/90-mm MgB "Finger" MRI Magnet for Osteoporosis Screening: Two Design Options.

In this paper we present two design options for a tabletop liquid-helium-free, persistent-mode 1.5-T/90-mm MgB "finger" MRI magnet for osteoporosis screening. Both designs, one with and the other without an iron yoke, satisfy the following criteria: 1) 1.

A High-Resolution 1.3-GHz/54-mm LTS/HTS NMR Magnet.

A high-resolution 1.3-GHz/54-mm low-temperature superconducting/high-temperature superconducting (HTS) nuclear magnetic resonance magnet (1.3 G) is currently in the final stage at the Massachusetts Institute of Technology Francis Bitter Magnet Laboratory.

A 1.5-T Magic-Angle Spinning NMR Magnet: 4.2-K Performance and Field Mapping Test Results.

We present results of full-current testing at 4.2 K of a -axis 0.866-T solenoid and an -axis 1.

Direct Machining of Low-Loss THz Waveguide Components With an RF Choke.

We present results for the successful fabrication of low-loss THz metallic waveguide components using direct machining with a CNC end mill. The approach uses a split-block machining process with the addition of an RF choke running parallel to the waveguide. The choke greatly reduces coupling to the parasitic mode of the parallel-plate waveguide produced by the split-block.