Ion temperature \(T_\mathrm{ion}\) is an essential parameter for evaluating ignition performance in inertial confinement fusion (ICF) experiments. For a thermal plasma, the energy spectrum width of primary deuterium–tritium (DT) neutrons is utilized to diagnose the information about \(T_\mathrm{ion}\). Time-of-flight (TOF) systems and magnetic recoil spectrometers have been applied successfully in measurements of time-integrated neutron energy spectra, providing a burn-averaged ion temperature \(\left\langle {{T_{{\rm{ion}}}}} \right\rangle\). As the fusion yield increases, understanding the temporal evolution of a burning plasma is of critical importance. TOF signals at different distances can constrain the measurement of the time-dependent ion temperature \({\rm{d}}{T_{{\rm{ion}}}}/{\rm{d}}t\). This method leverages tomographic reconstruction techniques and needs a priori knowledge of other physical quantities. Herein, we demonstrate the potential of a high-resolution magnetic proton recoil (MPR) spectrometer for time-resolved ion temperature \({T_{{\rm{ion}}}}(t)\) diagnoses. The energy resolution and time resolution of the spectrometer are 100 keV and 1.6 ns, respectively. GEANT4 is used to simulate the detection process of DT neutrons with a time-dependent energy spectrum at a distance of 10–20 m. The simulated results are a set of waveform signals. We perform a time shift on each signal according to the accurate energy selection of the MPR spectrometer, which deducts the TOF contribution and uncouples the relationship between time and energy. Therefore, we obtain a time-resolved energy spectrum that enables the diagnosis of \({T_{{\rm{ion}}}}(t)\). For \({T_{{\rm{ion}}}}(t)\) increasing linearly from 3 keV to 5 keV within several nanoseconds, the mean absolute error and root mean squared error are 0.25 keV and 0.27 keV, respectively. High energy resolution is the most important because the accurate energy selection is the basis of this method. Closer distances and higher time resolution are obviously beneficial for improving diagnostic accuracy. This method is based on the fact that the MPR spectrometer is accurately calibrated, and no prior knowledge is required in diagnoses. The simulated performance is attractive for future fusion experiments driven by Z pulsed-power facilities.

ICF diagnose,time-resolved,neutron spectrum,MPR spectrometer