Ion spectrometer composed of time-of-flight and Thomson parabola spectrometers for simultaneous characterization of laser-driven ions

Abstract

An ion spectrometer, composed of a time-of-flight spectrometer (TOFS) and a Thomson parabola spectrometer (TPS), has been developed to measure energy spectra and to analyze species of laser-driven ions. Two spectrometers can be operated simultaneously, thereby facilitate to compare the independently measured data and to combine advantages of each spectrometer. Real-time and shot-to-shot characterizations have been possible with the TOFS, and species of ions can be analyzed with the TPS. The two spectrometers show very good agreement of maximum proton energy even for a single laser shot. The composite ion spectrometer can provide two complementary spectra measured by TOFS with a large solid angle and TPS with a small one for the same ion source, which are useful to estimate precise total ion number and to investigate fine structure of energy spectrum at high energy depending on the detection position and solid angle. Advantage and comparison to other online measurement system, such as the TPS equipped with microchannel plate, are discussed in terms of overlay of ion species, high-repetition rate operation, detection solid angle, and detector characteristics of imaging plate.

Accurate spectra for high energy ions by advanced time-of-flight diamond-detector schemes in experiments with high energy and intensity lasers

“…In the described experimental campaign, the advanced TOF method allowed to obtain calibrated spectra of protons up to ~ 2.5 MeV with very high accuracy, much better than that typically obtained with Thomson spectrometers 38,59 . It is worth to notice that the approaches here followed for estimating the range where the detected signal is assumed to be purely due to protons-based in one case on established theoretical considerations [2][3][4]41 and in the other case on the use of a suitable filter-results to be rather conservative, if compared with the energy spectra given in reference 60 . In that case data obtained by Thomson spectrometers, employed in experimental campaigns at very similar regimes to that described in the present paper, showed that the energy of carbon ions was significantly lower than the minimum proton energy considered in the present analysis 60 .…”

“…It is worth to notice that the approaches here followed for estimating the range where the detected signal is assumed to be purely due to protons-based in one case on established theoretical considerations [2][3][4]41 and in the other case on the use of a suitable filter-results to be rather conservative, if compared with the energy spectra given in reference 60 . In that case data obtained by Thomson spectrometers, employed in experimental campaigns at very similar regimes to that described in the present paper, showed that the energy of carbon ions was significantly lower than the minimum proton energy considered in the present analysis 60 . Hence, for future development of the technique discussed here, its simultaneous employment together with a Thomson spectrometer, placed at similar detection angle, will be fruitful for extending the effective energy range where a pure proton spectrum is retrievable.…”

Heavy-ion emission from short-pulse laser-plasma interactions with thin foils

“…In addition to being a platform for developing diagnostics for OMEGA-EP 22 and damage testing of optics, the MTW is being used for studies of LPI in the context of backlighter development and basic science. A Thomson parabola ion spectrometer (TPIS), [23][24][25][26][27] previously designed, constructed and implemented on the MTW, was used for measurements of charged particle energy spectra.…”

Calibration and Performance Tests of Detectors for Laser-Accelerated Protons

“…Even when such ultra-short pulses of protons are spread out over a flight path of 1-2 m due to different particle momenta, they will most likely produce an overlap signal inside a scintillator. Nevertheless, this type of detectors has been successfully applied for the measurement of energy spectra of laser-accelerated protons [10], [11]. Our design, as motivated in section II, tends to offer maximum flexibility to obtain the proton spectral distribution, especially at the high-energy limit, over a wide range of particle numbers.…”

“…The detection time after the laser pulse is directly related to the proton energy (time-offlight method, TOF) [11], [17]. In our case, the projected range of kinetic energies (0.5-15 MeV) corresponds to flight times between 153 and 30 ns at 1.5 m target distance, respectively.…”