Unit 9 Quiz Flashcards
At what temperature does an alloy of niobium and titanium become superconductive?
4 Kelvin
This is a percentage of time during the TR period that the gradient is permitted to be at maximum amplitude, or “work”, during an imaging sequence
Duty cycle
shielding accomplished by surrounding the magnet with steel plates
Passive shielding
substance with a small but positive magnetic susceptibility
Paramagnetism
uses metal discs/plates at installation to adjust for large changes in field homogeneity
Passive shimming
solenoid electromagnet that uses super-cooled coils of wire so that there is no inherent resistance in the system through which the current flows & therefore the magnetism is generated without a driving voltage
Superconductive electromagnets
magnets that retain their magnetism
Permanent magnets
supplies power to the gradient coils
Gradient amplifier
additional solenoid magnets to adjust field homogeneity
Active shimming
process whereby the evenness of the magnetic field is optimized
Shimming
Uses additional superconducting coils located at each end of the main magnet inside the cryostat to shield the system
Active shielding