Selective RF Gaussian Pulse Power Planning
A selective RF 90 degree pulse is used when a system needs rotation near a chosen resonance band. A Gaussian envelope is common because it starts smoothly, reaches a defined peak, and ends smoothly. This shape reduces abrupt transitions that may broaden excitation or stress hardware.
This calculator estimates the peak RF field required to create a target flip angle. It also converts that field into power using a practical coil calibration. The calibration says how much B1 is produced by a known power level. The tool then scales power with the square of the field ratio.
The duration and sigma values define the pulse shape. A longer pulse gives more time for rotation, so the peak field can fall. A wider sigma gives a fuller Gaussian area, but it can also change the bandwidth estimate. The truncation correction keeps the calculation tied to the entered duration, not to an infinite Gaussian.
The result includes peak B1, RMS B1, peak power, pulse average power, energy per pulse, train energy, estimated bandwidth, and optional slice thickness. RF chain loss and safety margin are included because real cables, switches, and matching networks waste power. The amplifier percentage helps compare the demand against a chosen limit.
Use the calculator as a planning aid, not as a safety certificate. Actual MRI, NMR, spectroscopy, or communications hardware may require vendor calibration, probe tuning, duty cycle limits, and SAR review. The estimate is most useful when the calibration was measured with the same coil, load, frequency, and pulse setup.
Good inputs improve the answer. Measure the reference B1 and reference power carefully. Use a realistic pulse length. Enter sigma based on the shape file or pulse design notes. Add losses in decibels when the reference point is not at the coil. Add margin when tuning may drift.
The CSV and PDF options make it easier to document setup choices. Keep records with sample, coil, frequency, and operator notes. This supports repeatable pulse planning and safer reviews.
Before use, compare the result with a low power test and a measured nutation curve. Small calibration errors can grow quickly because power follows a square law. Document temperature, loading, and frequency shifts when results are critical for later checks.