SELF-SHIELDED GRADIENT COIL ARRANGEMENTS WITH MINIMISED RISK OF PARTIAL DISCHARGE

摘要

Apparatus ( 10 ) for use in MRIS includes a coil arrangement having drive coils ( 20 ), shield coils ( 30 ) and a power supply unit (PSU) ( 40 ). The drive coils ( 20 ) and the shield coils ( 30 ) are connected in series to the PSU ( 40 ) to form a circuit. The shield coils ( 30 ) are connected between a first and second length of the drive coils ( 20 ) so as to straddle a virtual earth of the circuit. This is advantageous in minimising potential differences within the shield coil ( 30 ) assembly and thereby in minimising partial discharge therewithin. Partial discharge between adjacent parts of the drive coils ( 20 ) is minimised by spatially arranging those coils ( 20 ) such that parts thereof that are at a high electrical potential are spatially adjacent parts thereof that are simultaneously at a potential of the same polarity of at a low electrical potential of either polarity.