Table 1.
Technical specifications of the Impulse gradient coil
| Parameter | Value | ||
|---|---|---|---|
| Coil geometry | Three-step front design, from 600 to 440 mm inner diameter (weight 1,060 kg) | ||
| Performance | Gmax of 200 mT m−1; SR of 900 T m−1 s−1 (1,100 T m−1 s−1 maximum) | ||
| Gradient power amplifier | 1,200 A, 2,250 V | ||
| Peak acoustic noise (NEMA MS 4 MGAN) (dBa) | 120.6 (all axes combined) | ||
| Cooling | 31.7 °C at high duty cycle, 80 mT m−1 for 30 min | ||
| Active E-shims | First- and second-order harmonics | ||
| x | y | z | |
| Linearity in 20-cm-diameter sphere volume (%) | 5.73 | 6.32 | 5.64 |
| Sensitivity (mT m−1 A−1) | 0.16 | 0.16 | 0.16 |
| Maximum positional error (% of FOV) | 5.7 | 6.3 | 5.6 |
| Maximum pixel size error (% of nominal pixel) | 17.8 | 18.7 | 24.3 |
| Inductance (μH) | 315 | 383 | 315 |
| a.c. resistance (mΩ at 1 kHz) | 55 | 59 | 48 |
| Losses at 500 A (kW) | 13.7 | 14.7 | 12 |
| Field at cryostat at 1,200 A (root mean square) (mT) | 0.4 | 0.7 | 0.4 |
| Net force at 7 T at 1,200 A (N) | 143 | 155 | 8 |
| Net torque at 7 T at 1,200 A (Nm) | 28 | 150 | 0 |