In this paper we present two design options for a tabletop liquid-helium-free, persistent-mode 1.5-T/70-mm MgB2 “finger” MRI for osteoporosis screening. Both designs, one with and the other without an iron yoke, satisfy the following criteria: 1) 1.5-T center field with a 70-mm room-temperature bore for a finger to be placed at the magnet center; 2) spatial field homogeneity of <5 ppm over a...
The final commissioning of the 11.7 T Iseult magnet is going to start in the mid of 2017 at NEUROSPIN laboratory. Before that, the dedicated cryoplant, electrical equipment, control-process and instrumentation have already been installed and tested in order to validate all the operation parameters and the component capabilities. Cryogenic tests have been performed to confirm heat loads and...
Hyper Tech will report on progress that has been made on designing helium-free MgB2 magnets for 1.5 and 3.0 T full body MRI systems, including mechanical, thermal and quench protection analysis, conductor development, jointing, and prototype test coil characterization and measurements. As an addendum, the development of low AC loss MgB2 conductors for motors and generator will be presented.
As the global helium crisis continues, the need for liquid-helium-free superconducting magnets continuously increases in the commercial sector of magnetic resonance imaging (MRI) systems. However, the conventional low temperature superconductor (LTS) magnets frequently experience unpredictable premature quenches, resulting in the extra usage of liquid helium before an MRI machine is delivered...
Ultra-high field magnets are becoming fundamental in brain research in order to satisfy the higher requirements in tissue contrast, spectral resolution and signal to noise ratio. ASG is putting a lot of effort to be competitive in this sector. After a 7 T conceptual design (1) , now ASG is working on an 11.74 T MRI magnet for the Gachon University GIL Hospital.In this project, ASG has the...
The variation of the magnetic flux density due to shielding current attenuation causes negative influence on temporally stable magnetic flux density required at the center of high-resolution MRI magnets. We have already clarified the relationship between the maximum current in an overshooting process and the shielding magnetic flux density attenuation and established the estimation method of...
This work describes magnetic, mechanical, and thermal Finite Element Modeling (FEM) studies in support of a whole body 3 T MRI magnet based on conduction cooling. As a strand, both 1G and 2G MgB2 conductors were considered. An optimization code to design the main coil segment layout and winding size was used. Thermal FEM modeling was used to estimate the temperature gradient on the coils in...
A superconducting magnet commonly used in current MRI systems should be operated in the persistent current mode (PCM) to yield a high-resolution level that requires a magnetic field drift of less than 0.01 ppm/h. To acquire the required field homogeneity as a function of time, the availability and even reproducibility of a superconducting joint technique enabling the PCM of the magnet should...
There are two major problems for introducing HTS-MRI magnets. One is a long-lasting attenuation of screening current induced on the superconducting tapes at the initial excitation. The screening current affects the MRI field stability both temporally and spatially. Another is that it is by now difficult to realize a superconducting junction of REBCO tapes and a superconducting switch for the...
A 1.5 T cryogen free superconducting magnet for a dedicated orthopedic MRI of human extremities was developed and tested. The magnet has a compact cryostat cooled by a pulse tube coldhead with cooling power of 1 W at 4.2 K. The warm bore of a cryostat is 325 mm in diameter, 600 mm in length. Cost effective NbTi wire was used for making superconducting coils. The magnet is actively shielded....
The CERN’s projects, HL-LHC and FCC, will create a big push in the state of the art of High-Field Superconducting magnets . The performance of superconducting materials such as Nb3Sn and HTS will be developed to yield higher performance at lower costs and the construction materials and techniques will be advanced. In the context of Energy’s savings, Industry is experiencing a renewed interest...
The joint-less coil is wound by ‘‘wind-and-flip’ technique. Due to the absence of resistive joint, the coil enable the current to flow in an absolutely superconducting closed loop, therefore it can load a DC current persistently without power supply. Therefore, the coil shows a great potential on MRI/NMR, permanent magnet and rotor magnet of HTS machines. This paper is to study the trapped...
MRI is widely used for diagnosis and characterization of many diseases and injuries. It has immense potential for early diagnosis of cancer through well-patient screening, but that potential is largely unrealized because the cost of dye-contrast MRI is $thousands and it is not affordable to screen well patients. We have employed a new methodology of magnetic design to project a domain of...
