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, Available online , doi: 10.11884/HPLPB202436.230316
Abstract:
The structural models of Si-doped glow discharge polymer (Si-GDP) were established using reactive force field molecular dynamics simulation (ReaxFF MD), and the effects of silicon content, hydrogen content, and density on its hybrid carbon bonding and mechanical properties were investigated. The results show that with the silicon content increasing, the molecules tend to form a silicon-containing macromolecule, and the types and number of small molecules decrease, the silicon content improves the mechanical properties by promoting the binding of carbon and silicon atoms and inhibiting the formation of end-group sp3CH3. Besides, species such as ·C2H3, ·C3H5 and ·Si(CH3)3 were found during the formation of Si-GDP, which were in good agreement with the thin film deposition experiment of glow discharge polymer. The hydrogen content is measured as the atomic ratio of hydrogen to carbon and silicon, as the ratio grows, the number of model molecules did not change significantly, the ratio of sp3C and sp3CH3 increased, and the hydrogen content decreased the mechanical properties mainly by promoting the formation of sp3CH3. With the density increasing, the number of molecular species in the model did not change much, and the proportion of sp2C in the model was significantly increased, while the proportion of sp3C was slightly increased, the mechanical properties of Si-doped hydrogenated amorphous carbon were mainly improved by increasing the proportion of sp2C. This study provides an example for constructing Si-GDP by ReaxFF MD, and may provide a new method and reference for evaluating the structure and mechanical properties of Si-GDP.
The structural models of Si-doped glow discharge polymer (Si-GDP) were established using reactive force field molecular dynamics simulation (ReaxFF MD), and the effects of silicon content, hydrogen content, and density on its hybrid carbon bonding and mechanical properties were investigated. The results show that with the silicon content increasing, the molecules tend to form a silicon-containing macromolecule, and the types and number of small molecules decrease, the silicon content improves the mechanical properties by promoting the binding of carbon and silicon atoms and inhibiting the formation of end-group sp3CH3. Besides, species such as ·C2H3, ·C3H5 and ·Si(CH3)3 were found during the formation of Si-GDP, which were in good agreement with the thin film deposition experiment of glow discharge polymer. The hydrogen content is measured as the atomic ratio of hydrogen to carbon and silicon, as the ratio grows, the number of model molecules did not change significantly, the ratio of sp3C and sp3CH3 increased, and the hydrogen content decreased the mechanical properties mainly by promoting the formation of sp3CH3. With the density increasing, the number of molecular species in the model did not change much, and the proportion of sp2C in the model was significantly increased, while the proportion of sp3C was slightly increased, the mechanical properties of Si-doped hydrogenated amorphous carbon were mainly improved by increasing the proportion of sp2C. This study provides an example for constructing Si-GDP by ReaxFF MD, and may provide a new method and reference for evaluating the structure and mechanical properties of Si-GDP.
, Available online , doi: 10.11884/HPLPB202436.240053
Abstract:
This review article aims at summarizing the basic principles of circuit methods used in compact pulsed-power generators. The concept of energy storage and voltage adding has been explained followed by the descriptions on switching unit design and control signal generation. Some examples of applications of these circuit methods are given that include Marx circuit using capacitor energy storage, Marx circuit using inductive energy storage, Marx circuit using hybrid energy storage, linear transformer driver (LTD) circuit using capacitive energy storage and LTD circuit using inductive energy storage.
This review article aims at summarizing the basic principles of circuit methods used in compact pulsed-power generators. The concept of energy storage and voltage adding has been explained followed by the descriptions on switching unit design and control signal generation. Some examples of applications of these circuit methods are given that include Marx circuit using capacitor energy storage, Marx circuit using inductive energy storage, Marx circuit using hybrid energy storage, linear transformer driver (LTD) circuit using capacitive energy storage and LTD circuit using inductive energy storage.
, Available online , doi: 10.11884/HPLPB202436.230392
Abstract:
The breakdown characteristics of trigger gap for the pre-ionization switch in N2, the mixture of N2 and SF6 and SF6 atmosphere under positive and negative pulse were investigated for the higher voltage grade and bipolarity application. The relationships between the breakdown voltage and delay time of the pre-ionization gap and the pressure of different kinds of gases were obtained, and the breakdown characteristics were compared for the pre-ionization gap under positive and negative polarities. The results of the experiment demonstrate that the breakdown process of the gap in N2 was more stable, and the linearity of breakdown voltage varying with pressure in N2 was the best among the three kinds of gases. The breakdown voltage was saturated only in SF6 with the increase of gas pressure. The breakdown voltage of the gap under negative polarity was higher than that under the positive at some certain values of the pressure, and this phenomenon might suggest that there was a polarity effect upon the breakdown process of pre-ionization gap. Compared with the mixture and N2, the absolute differences between negative and positive polarity for both breakdown voltage and delay time in SF6 were relatively higher. N2 should be preferred as the insulating medium for the pre-ionization gap to reduce the synchronization delay difference of the bipolar self-triggered switches. The polarity effect of the pre-ionization gap and the distinctions among the different kinds of insulated gas medium should be paid more attention in engineering applications for the pre-ionization gap.
The breakdown characteristics of trigger gap for the pre-ionization switch in N2, the mixture of N2 and SF6 and SF6 atmosphere under positive and negative pulse were investigated for the higher voltage grade and bipolarity application. The relationships between the breakdown voltage and delay time of the pre-ionization gap and the pressure of different kinds of gases were obtained, and the breakdown characteristics were compared for the pre-ionization gap under positive and negative polarities. The results of the experiment demonstrate that the breakdown process of the gap in N2 was more stable, and the linearity of breakdown voltage varying with pressure in N2 was the best among the three kinds of gases. The breakdown voltage was saturated only in SF6 with the increase of gas pressure. The breakdown voltage of the gap under negative polarity was higher than that under the positive at some certain values of the pressure, and this phenomenon might suggest that there was a polarity effect upon the breakdown process of pre-ionization gap. Compared with the mixture and N2, the absolute differences between negative and positive polarity for both breakdown voltage and delay time in SF6 were relatively higher. N2 should be preferred as the insulating medium for the pre-ionization gap to reduce the synchronization delay difference of the bipolar self-triggered switches. The polarity effect of the pre-ionization gap and the distinctions among the different kinds of insulated gas medium should be paid more attention in engineering applications for the pre-ionization gap.
, Available online , doi: 10.11884/HPLPB202436.230347
Abstract:
To meet the requirements of multi-channel precise synchronous trigger switch, photo conductive semiconductor switch (PCSS) is combined with V/N gas switch, which takes advantage of the photoelectric isolation, low trigger threshold, low delay time jitter and photoelectric isolation of PCSS, as well as the advantages of high operating voltage and strong load capacity of V/N gas switch. The core of the combination of the two switches is that the structural parameters of the V/N gas switch match the parameters of the PCSS trigger loop. The structural capacitance, trigger loop oscillation parameters and switching electric field distribution of the V/N gas switch are analyzed and calculated. The relationship between the structural capacitance of the V/N gas switch and the oscillation loop composed of PCSS and series inductors is studied. The self-breakdown voltage curve, on-delay time and delay time jitter of the switch under different under voltage ratios are obtained. The performance of the V/N gas switch for PCSS triggering is preliminarily verified.
To meet the requirements of multi-channel precise synchronous trigger switch, photo conductive semiconductor switch (PCSS) is combined with V/N gas switch, which takes advantage of the photoelectric isolation, low trigger threshold, low delay time jitter and photoelectric isolation of PCSS, as well as the advantages of high operating voltage and strong load capacity of V/N gas switch. The core of the combination of the two switches is that the structural parameters of the V/N gas switch match the parameters of the PCSS trigger loop. The structural capacitance, trigger loop oscillation parameters and switching electric field distribution of the V/N gas switch are analyzed and calculated. The relationship between the structural capacitance of the V/N gas switch and the oscillation loop composed of PCSS and series inductors is studied. The self-breakdown voltage curve, on-delay time and delay time jitter of the switch under different under voltage ratios are obtained. The performance of the V/N gas switch for PCSS triggering is preliminarily verified.
, Available online , doi: 10.11884/HPLPB202436.230410
Abstract:
The study of vacuum surface flashover along the insulator ring was carried out. An experimental platform for vacuum insulator stack was built. The influence of flashover among insulator ring on the voltage of the vacuum insulator stack was evaluated by equivalent circuit model. Vacuum surface flashover along the three kinds of material insulator stacks were carried out, which verify the availability and reliability of the experimental platform. This work provides a reference for the engineering research of the vacuum insulator stack of pulse power device, and also provides an experimental platform for research of new insulation materials.
The study of vacuum surface flashover along the insulator ring was carried out. An experimental platform for vacuum insulator stack was built. The influence of flashover among insulator ring on the voltage of the vacuum insulator stack was evaluated by equivalent circuit model. Vacuum surface flashover along the three kinds of material insulator stacks were carried out, which verify the availability and reliability of the experimental platform. This work provides a reference for the engineering research of the vacuum insulator stack of pulse power device, and also provides an experimental platform for research of new insulation materials.
, Available online , doi: 10.11884/HPLPB202436.230337
Abstract:
Based on the requirement of high current multi-pulse accelerator, the surface flashover characteristics of cross-linked polystyrene (XLPS) material under burst multi-pulse in vacuum were studied experimentally. Vacuum surface flashover experiments were carried out with XLPS samples placed in flat electrodes under single pulse and three pulses with interval of 500 ns. Special phenomena such as continuous decrease of equivalent impedance of vacuum surface before flashover and continuous maintenance of flashover channel after pulse end were observed, and statistical data of vacuum surface flashover of XLPS materials under corresponding conditions were obtained. On the basis of experiments, the flashover characteristics of XLPS in vacuum under high repetition rate multi-pulse loading are analyzed, which provides experimental basis for insulation design of high repetition rate multi-pulse accelerator.
Based on the requirement of high current multi-pulse accelerator, the surface flashover characteristics of cross-linked polystyrene (XLPS) material under burst multi-pulse in vacuum were studied experimentally. Vacuum surface flashover experiments were carried out with XLPS samples placed in flat electrodes under single pulse and three pulses with interval of 500 ns. Special phenomena such as continuous decrease of equivalent impedance of vacuum surface before flashover and continuous maintenance of flashover channel after pulse end were observed, and statistical data of vacuum surface flashover of XLPS materials under corresponding conditions were obtained. On the basis of experiments, the flashover characteristics of XLPS in vacuum under high repetition rate multi-pulse loading are analyzed, which provides experimental basis for insulation design of high repetition rate multi-pulse accelerator.
, Available online , doi: 10.11884/HPLPB202436.240004
Abstract:
The RbTiOPO4 crystal Raman emission at high-order Stokes with 271 cm−1 shift driven by an end-pumped passively Q-switched laser was demonstrated. The Nd:YAG and Cr4+:YAG bonding design was used to reduce the intracavity loss and make the laser system compact, so as to raise the intracavity photon density, which proved helpful for the conversion of Raman shift to high-order Stokes light. The first-Stokes laser with different Raman shifts is designed to oscillate in different cavities, and the first-Stokes laser with 687 cm−1 shift is suppressed by using the difference in cavity mode matching with the fundamental laser, and the fifth-order Stokes laser with 271 cm−1 shift is obtained. Under the pump power of 8.1 W, a 1 244 nm wavelength laser with an average output power of 230 mW was obtained, and the corresponding pulse width and pulse frequency repetition were 2.9 ns and 11.7 kHz, respectively. The 1 244 nm laser wavelength perfectly matched the OH−1 absorption peak in water, which could have significant applications in fields such as surface vegetation and planetary water detection.
The RbTiOPO4 crystal Raman emission at high-order Stokes with 271 cm−1 shift driven by an end-pumped passively Q-switched laser was demonstrated. The Nd:YAG and Cr4+:YAG bonding design was used to reduce the intracavity loss and make the laser system compact, so as to raise the intracavity photon density, which proved helpful for the conversion of Raman shift to high-order Stokes light. The first-Stokes laser with different Raman shifts is designed to oscillate in different cavities, and the first-Stokes laser with 687 cm−1 shift is suppressed by using the difference in cavity mode matching with the fundamental laser, and the fifth-order Stokes laser with 271 cm−1 shift is obtained. Under the pump power of 8.1 W, a 1 244 nm wavelength laser with an average output power of 230 mW was obtained, and the corresponding pulse width and pulse frequency repetition were 2.9 ns and 11.7 kHz, respectively. The 1 244 nm laser wavelength perfectly matched the OH−1 absorption peak in water, which could have significant applications in fields such as surface vegetation and planetary water detection.