In this paper, a novel compact magnetic sector mass spectrometer has been developed and tested at the Lanzhou Institute of Physics. Its design is based on the mass separation of a 90° magnetic sector-field analyzer with a double trajectory, which has a magnetic induction of 0.7 T. The instrument can record mass range from 1 to 50 amu based on two special trajectories when the accelerating voltage of the ion source changes from 200 V to 2500 V. The dimensions of the device together with the electronic unit are approximately 220 × 165 × 165 mm3 (length × depth × height). The weight is 10.2 kg and the maximum power consumption was measured to be 20 W. The instrument successfully provided mass spectrum information on the vacuum test chamber, resolving power of about 58 at full width half maximum (FWHM), and demonstrated a sensitivity of 7.2 × 10−5 A Pa−1. The compact magnetic sector mass spectrometer is designed for space application and can be extended to other portable analytical fields on Earth.
We present particle-in-cell (PIC) simulations of laser plasma instabilities (LPIs) with a laser pulse duration of a few picoseconds. The simulation parameters are appropriate to the planar-target LPI experimental conditions on SG-II. In this regime, the plasmas are characterized by a long electron density scale length and a large electron density range. It is found that when the incident laser intensity is well above its backward stimulated Raman scattering (backward SRS, BSRS) threshold, the backscattered light via the primary BSRS is intense enough to excite secondary SRS (Re-SRS) in the region below one-ninth of the critical density of the incident laser. The daughter light wave via the secondary BSRS (Re-BSRS) is amplified as it propagates toward the higher-density region in the bath of broadband light generated through the primary BSRS process. A higher intensity of the incident laser not only increases the amplitude of the BSRS light but also increases the convective amplification lengths of the Re-BSRS modes by broadening the spectrum of the BSRS light. Convective amplification of Re-BSRS causes pump depletion of the primary BSRS light and may lead to an underestimate of the primary BSRS level in SP-LPI experiments. A significant fraction of the generation of energetic electrons is strongly correlated with the Re-BSRS modes and should be considered as a significant energy loss.
In recent years, high-resolution mass spectrometers have been applied and made tunable to various fields. In this study, a prototype magnetic sector mass spectrometer with high resolving power has been developed. Its design is based on employing a 90 • magnetic sector-field analyzer with double trajectory, a miniature Nier-type ion source and two channel-type electron multipliers for ion detection. The ion accelerating voltage is controllable from 200 to 2500 V and the mass range demonstrated herein is (1-73) amu. The resolution of the instrument for the lower mass channel helium and higher mass channel nitrogen is about 0.008 amu and 0.05 amu (full width at half maximum), respectively, or m/∆m ≈ 550 in the whole mass range of (1-40) amu. The present sensitivity is measured to be approximately 8.4 × 10 −5 A/Pa.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.