17 results on '"Zhang, Beizhen"'
Search Results
2. An Axial Foilless Diode Guided by Composite Magnetic Field for the Production of Relativistic Electron Beams
- Author
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Li Fei, Xiao Jin, Li Chunxia, Gong Haitao, Falun Song, Zhang Beizhen, Gan Yanqing, and Wang Ganping
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Materials science ,Article Subject ,business.industry ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics ,Anode ,Magnetic field ,Optics ,Magnet ,Cathode ray ,Electrical and Electronic Engineering ,business ,Electrical impedance ,Microwave ,Voltage ,Diode - Abstract
Foilless diode are widely used in high-power microwave devices, but the traditional foilless diodes have large volume, heavy weight, and high power consumption, which are not conducive to the application of high-power microwave system on mobile platform. In order to reduce the size of the foilless diode, improve the transmission efficiency of electron beams, and reduce the weight and power consumption of the guiding magnetic field system, an axial foilless diode with a composite guiding magnetic field system is developed in this paper. By adjusting the structure size and magnetic field parameters of solenoid coil, permanent magnet, and soft magnet, the configuration of the composite magnetic field is optimized. The diameter of the anode tube is about 40% smaller than that of the original structure, and the weight and power consumption of the guiding magnetic system are about 40% lower than that of the original system when the same axial magnetic field intensity in the uniform region is generated. When the magnetic field strength of the permanent magnet is set as 1.4 T and that of the solenoid coil is in the range of 0.5 T∼1 T, the electron beam transmission efficiency is 100%, and the diode impedance is adjustable in the range of 100 Ω∼240 Ω. The experimental results verify the correctness of the simulation analysis. The experimental results show that when the magnetic field strength of the solenoid coil is 0.98 T (0.5 T) and that of the permanent magnet is 1.4 T, the transmission efficiency of the high-current annular electron beam with a peak voltage of 636 kV (590 kV) and a peak current of 3.3 kA (2.6 kA) is 100%, and the diode impedance is about 194 Ω (220 Ω).
- Published
- 2021
3. Electrode Erosion and Lifetime Performance of a Compact and Repetitively Triggered Field Distortion Spark Gap Switch
- Author
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Bucur M. Novac, Xiao Jin, Zhang Beizhen, Li Chunxia, Falun Song, Gong Haitao, Wang Ganping, Gan Yanqing, Li Fei, Ivor R. Smith, and Mingdong Zhu
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Nuclear and High Energy Physics ,Materials science ,business.industry ,Electrode erosion ,Insulator (electricity) ,Spark gap ,Condensed Matter Physics ,01 natural sciences ,010305 fluids & plasmas ,Sputtering ,0103 physical sciences ,Electrode ,Surface roughness ,Optoelectronics ,business ,Jitter ,Voltage - Abstract
The electrode erosion and lifetime performance of a compact and repetitively triggered field distortion spark gap switch were studied at a repetitive frequency rate of 30 Hz, a peak current of 8.5 kA, and a working voltage of ±35 kV when the switch was filled with a gas mixture of 30% SF6 and 70% N2 at a pressure of 0.3 MPa. The variations of the time-delay jitter and the self-breakdown voltage were both studied for the whole service lifetime of the spark gap switch. The morphology of both the electrodes and the plate insulator, before and after the service lifetime tests, is also analyzed. The results show that during these tests, the time-delay jitter is basically synchronized with the self-breakdown voltage jitter, and both undergo firstly a process of rapidly decreasing their values, then remaining stable, and finally and gradually increasing after 70 000 pulses. The change in the electrode surface roughness (i.e., surface profile) is caused by erosion and chemical deposits in the switch cavity, which are mainly the two factors that affect the time-delay jitter of the switch. Tip protrusions on the electrode surface, due to electrode erosion, contribute to reducing the time-delay jitter. However, due to chemical reactions, fluorides and sulfides are deposited on the switch components, as well as metal particles caused by electrode erosion sputtering. Slowly, after a large number of shots, all these phenomena affect the self-breakdown performance resulting in an increased self-breakdown voltage jitter, which also causes the time-delay jitter to increase. Although there are a number of reasons that contribute to the deterioration of the performance of the switch, it is fortunate that if a switch suffering a degraded performance is reassembled, with the electrodes mechanically polished and all the components cleaned, the optimal performance of the switch can be restored. If maintenance work is carried out regularly to preserve the condition of the switch’s inner components, the service lifetime of the switch can be prolonged.
- Published
- 2020
4. Development and testing of a three-section pulse-forming network and its application to Marx circuit
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Xiao Jin, Wang Ganping, Li Fei, Li Chunxia, Gong Haitao, Gan Yanqing, Falun Song, and Zhang Beizhen
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Physics ,Pulse forming network ,business.industry ,Condensed Matter Physics ,Inductor ,Capacitance ,Atomic and Molecular Physics, and Optics ,Marx generator ,law.invention ,Capacitor ,Optics ,Fall time ,law ,Rise time ,Waveform ,Electrical and Electronic Engineering ,business - Abstract
A three-section pulse forming network (PFN) based on Guillemin type-C circuit was developed to meet the challenge of a compact design, high withstand voltage, and high-quality output waveform with fast rise time, flat-top duration, and 100-ns pulse width. A simplified pulse forming circuit was proposed and studied that includes only three LC-sections connected in parallel, with each section containing an inductor and a capacitor connected in series. The effect of the capacitance deviation on the output waveform was investigated. The simulation results show that when the capacitance deviation exceeds +3%, both the flat top and fall time of the output waveform of single PFN module deteriorate greatly. Fortunately, in a multi-stage PFN-Marx circuit, even if the capacitance deviation exceeds +10%, when the average capacitance of the same LC sections is close to the theoretical value, the output waveform maintains a good quality and is in good agreement with the theoretical prediction. The compact three-section PFN developed during this project has a size of only 360 mm × 342 mm × 65 mm, and a maximum withstand voltage of 120 kV. Sixteen PFN stages were assembled to form a Marx generator with design parameters to provide of an output peak power of 12 GW and a maximum peak current of 15 kA. The tested output waveform agrees well with the theoretical results, having a rise time of 31 ns, a flat-top of 104 ns, and a pulse with of 164 ns.
- Published
- 2019
5. Analysis of the Optimal Operation Frequency With Lowest Time-Delay Jitter for an Electrically Triggered Field-Distortion Spark Gap
- Author
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Wang Ganping, Mingdong Zhu, Ivor R. Smith, Li Chunxia, Bucur M. Novac, Gong Haitao, Li Fei, Zhang Beizhen, Falun Song, Xiao Jin, and Gan Yanqing
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Physics ,Nuclear and High Energy Physics ,Range (particle radiation) ,Work (thermodynamics) ,Field (physics) ,Distortion ,Acoustics ,0103 physical sciences ,Spark gap ,Condensed Matter Physics ,01 natural sciences ,010305 fluids & plasmas ,Jitter - Abstract
This work was stimulated by the assumption that for a gas-filled spark gap closing switch operating at a high repetition frequency, there is an optimal frequency range in which the time-delay jitter reaches a minimum value. The experiments to test this assumption use an electrically triggered, field-distortion spark gap filled with the SF6/N2 gas mixture. The results show that indeed, the time-delay jitter decreases for a range of frequencies for which the filling gas can substantially restore the interelectrode insulation before increasing at a higher operation frequency. The experimental results demonstrate the correctness of the abovepresented assumption: the time-delay jitter of the field-distortion spark gap has its minimum when the unit operates in the repetition frequency range between 20 and 30 Hz. Since the recovery time depends on the gas species and the gap distance, the optimum operation frequency range should also vary depending on the spark-gap distance and the filling gas properties.
- Published
- 2019
6. A Compact and Repetitively Triggered, Field-Distortion Low-Jitter Spark-Gap Switch
- Author
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Bucur M. Novac, Falun Song, Gong Haitao, Wang Ganping, Zhang Beizhen, Ivor R. Smith, Gan Yanqing, Xiao Jin, Li Fei, Mingdong Zhu, and Li Chunxia
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Nuclear and High Energy Physics ,Range (particle radiation) ,Materials science ,business.industry ,Spark gap ,Condensed Matter Physics ,01 natural sciences ,Stability (probability) ,010305 fluids & plasmas ,Inductance ,Distortion ,0103 physical sciences ,Electrode ,Optoelectronics ,business ,Jitter ,Voltage - Abstract
This paper describes the development of a small field-distortion spark gap switch. Comprehensive experimental studies made with the switch revealed its self-breakdown characteristics, voltage operating range, time delay and jitter, repetition frequency, and finally the electrode erosion processes and duration of its service lifetime. A series of design improvements were required to be implemented in the switch design. For example, to reduce the structural inductance of the switch and to improve its working characteristics, the main electrode was designed as a circular track structure. Similarly, to increase the operation stability and reduce the self-breakdown probability, the trigger electrode was designed as a disk-like structure. Moreover, to balance the gas pressure in the discharge region and increase the stability during closure, a circular hole was added at the center of the trigger electrode. The compact switch has a small size of only 150 mm $\times42$ mm, a weight of 1.5 kg, and can be successfully operated at a voltage over 110 kV, at a repetition rate between 1 and 50 Hz and having a jitter of less than 4 ns. It was experimentally demonstrated that during normal operation conditions, the switch lifetime exceeds 100 000 shots.
- Published
- 2019
7. Recent advances in compact repetitive high-power Marx generators
- Author
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Gong Haitao, Zhang Beizhen, Xiao Jin, Wang Ganping, Mingdong Zhu, Gan Yanqing, Falun Song, Li Chunxia, and Li Fei
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Computer science ,business.industry ,Pulse generator ,Electrical engineering ,Spark gap ,Pulsed power ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics ,Marx generator ,law.invention ,Generator (circuit theory) ,law ,Constant current ,Blumlein Pair ,Electrical and Electronic Engineering ,Resistor ,business - Abstract
This paper introduces recent activities on Marx-based compact repetitive pulsed power generators at the Institute of Applied Electronics (IAE), China Academy of Engineering Physics (CAEP), over the period 2010–2018. A characteristic feature of the generators described is the use of a simplified bipolar charged Marx circuit, in which the normal isolation resistors or inductors to ground are removed to make the circuit simpler. Several pulse-forming modules developed to generate a 100 ns square wave output are introduced, including thin-film dielectric lines of different structures, a pulse-forming line based on a Printed Circuit Board, and non-uniform pulse-forming networks. A compact repetitive three-electrode spark gap switch with low-jitter, high-voltage, and high-current was developed and is used in the generators. A positive and negative series resonant constant current power supply with high precision and high power is introduced. As an important part of the repetitive pulse power generator, a lower jitter pulse trigger source is introduced. Several typical high-power repetitive pulsed power generators developed at IAE are introduced including a 30 GW low-impedance Marx generator, a compact square-wave pulse generator based on Kapton-film dielectric Blumlein line, a 20 GW high pulse-energy repetitive PFN-Marx generator, and a coaxial Marx generator based on ceramic capacitors. The research of key technologies and their development status are discussed, which can provide a reference for the future development and application of miniaturization of compact and repetitive Marx generators.
- Published
- 2019
8. Electrode Erosion and Lifetime Performance of a Compact and Repetitively Triggered Field Distortion Spark Gap Switch
- Author
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Song, Falun, primary, Novac, Bucur M., additional, Smith, Ivor R., additional, Li, Fei, additional, Zhang, Beizhen, additional, Zhu, Mingdong, additional, Li, Chunxia, additional, Wang, Ganping, additional, Gong, Haitao, additional, Gan, Yanqing, additional, and Jin, Xiao, additional
- Published
- 2020
- Full Text
- View/download PDF
9. GV/cm scale laser-magnetic resonant acceleration in vacuum
- Author
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Zhang Beizhen, Yunjun Gu, Jinlong Jiao, Zhiyu Zhang, and Y. Zhang
- Subjects
Physics ,Scale (ratio) ,Magnitude (mathematics) ,Electron ,Condensed Matter Physics ,Laser ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Collimated light ,Square (algebra) ,010305 fluids & plasmas ,Magnetic field ,law.invention ,Acceleration ,law ,0103 physical sciences ,Electrical and Electronic Engineering ,Atomic physics ,010306 general physics - Abstract
Resonant acceleration of electrons by a laser in the background of an extra longitudinal magnetic field is investigated analytically and numerically. The resonant condition is independent of laser intensity, and when satisfied, the energy gain is proportional to $a_0^2 $ and the square of phase difference. This process is mainly limited by the magnitude and spatial size of the extra magnetic field. Under the laboratory conditions, simulation results show that a monoenergetic and collimated electron bunch can still be obtained in ~ GV/cm scale, which sheds a light on the vacuum table-top laser-driven electron accelerators.
- Published
- 2017
10. Generating high-yield positrons and relativistic collisionless shocks by 10 PW laser
- Author
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Yunjun Gu, Wei Hong, Jinqing Yu, Jinlong Jiao, Teng Jian, Deng Zhigang, Shukai He, Yan Yonghong, Zhang Beizhen, and Zhijun Zhang
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Physics ,Astrophysics::High Energy Astrophysical Phenomena ,Cosmic ray ,Plasma ,Condensed Matter Physics ,Laser ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Charged particle ,010305 fluids & plasmas ,Computational physics ,Pulse (physics) ,Shock (mechanics) ,law.invention ,Acceleration ,Positron ,Physics::Plasma Physics ,law ,0103 physical sciences ,Electrical and Electronic Engineering ,Atomic physics ,010306 general physics - Abstract
Relativistic collisionless shock charged particle acceleration is considered as a possible origin of high-energy cosmic rays. However, it is hard to explore the nature of relativistic collisionless shock due to its low occurring frequency and remote detecting distance. Recently, there are some works attempt to solve this problem by generating relativistic collisionless shock in laboratory conditions. In laboratory, the scheme of generation of relativistic collisionless shock is that two electron–positron pair plasmas knock each other. However, in laboratory, the appropriate pair plasmas have been not generated. The 10 PW laser pulse maybe generates the pair plasmas that satisfy the formation condition of relativistic collisionless shock due to its ultrahigh intensity and energy. In this paper, we study the positron production by ultraintense laser high Z target interaction using numerical simulations, which consider quantum electrodynamics effect. The simulation results show that the forward positron beam up to 1013/kJ can be generated by 10 PW laser pulse interacting with lead target. The estimation of relativistic collisionless shock formation shows that the positron yield satisfies formation condition and the positron divergence needs to be controlled. Our results indicate that the generation of relativistic collisionless shock by 10 PW laser facilities in laboratory is possible.
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- 2017
11. Enhancement of the surface emission at the fundamental frequency and the transmitted high-order harmonics by pre-structured targets
- Author
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Zhang Beizhen, Sanwei Li, X. T. He, Chao Zheng, K. Q. Pan, Liangfu Guo, Z. C. Li, Dong Yang, and S. E. Jiang
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Physics ,Nuclear and High Energy Physics ,business.industry ,Plasma ,Electron ,Fundamental frequency ,Radiation ,Laser ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,law.invention ,Intensity (physics) ,010309 optics ,Optics ,Nuclear Energy and Engineering ,law ,Harmonics ,0103 physical sciences ,010306 general physics ,business ,Order of magnitude - Abstract
Laser interaction with an ultra-thin pre-structured target is investigated with the help of both two-dimensional and three-dimensional particle-in-cell simulations. With the existence of a periodic structure on the target surface, the laser seems to penetrate through the target at its fundamental frequency even if the plasma density of the target is much higher than the laser’s relativistically critical density. The particle-in-cell simulations show that the transmitted laser energy behind the pre-structured target is increased by about two orders of magnitude compared to that behind the flat target. Theoretical analyses show that the transmitted energy behind the pre-structured target is actually re-emitted by electron ‘islands’ formed by the surface plasma waves on the target surfaces. In other words, the radiation with the fundamental frequency is actually ‘surface emission’ on the target rear surface. Besides the intensity of the component with the fundamental frequency, the intensity of the high-order harmonics behind the pre-structured target is also much enhanced compared to that behind the flat target. The enhancement of the high-order harmonics is also related to the surface plasma waves generated on the target surfaces.
- Published
- 2019
12. Analysis of the Optimal Operation Frequency With Lowest Time-Delay Jitter for an Electrically Triggered Field-Distortion Spark Gap
- Author
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Song, Falun, primary, Li, Fei, additional, Zhang, Beizhen, additional, Zhu, Mingdong, additional, Li, Chunxia, additional, Wang, Ganping, additional, Gong, Haitao, additional, Gan, Yanqing, additional, Jin, Xiao, additional, Novac, Bucur M., additional, and Smith, Ivor R., additional
- Published
- 2019
- Full Text
- View/download PDF
13. A Compact and Repetitively Triggered, Field-Distortion Low-Jitter Spark-Gap Switch
- Author
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Song, Falun, primary, Li, Fei, additional, Zhang, Beizhen, additional, Zhu, Mingdong, additional, Li, Chunxia, additional, Wang, Ganping, additional, Gong, Haitao, additional, Gan, Yanqing, additional, Jin, Xiao, additional, Novac, Bucur M., additional, and Smith, Ivor R., additional
- Published
- 2019
- Full Text
- View/download PDF
14. Two-plasmon decay instability of the backscattered light of stimulated Raman scattering
- Author
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Chao Zheng, X. T. He, Zhang Beizhen, K. Q. Pan, Liang Guo, Qian Wang, Sanwei Li, Z. C. Li, Dong Yang, and S. E. Jiang
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Nuclear and High Energy Physics ,Materials science ,Electron ,Condensed Matter Physics ,01 natural sciences ,Instability ,010305 fluids & plasmas ,symbols.namesake ,Physics::Plasma Physics ,0103 physical sciences ,symbols ,Scattered light ,Atomic physics ,010306 general physics ,Saturation (magnetic) ,Excitation ,Plasmon ,Raman scattering - Abstract
The two-plasmon decay (TPD) instability of the backscattered light of the simulated Raman scattering (SRS) is first investigated with the help of one-dimensional (1D) and two-dimensional (2D) particle-in-cell (PIC) simulations. The 2D PIC simulation results show that the backscattered light of the SRS does excite TPD instability. Further, the comparison between 1D and 2D PIC simulation results shows that the backward SRS is suppressed by the excitation of TPD instability, which means the TPD instability of the scattered light could be a saturation scheme of SRS. It is also shown that, after the excitation of TPD, the electrons could experience a two-stage or even three-stage acceleration and their energy may reach to or even exceed 100 KeV, which means the TPD instability of the backscattered light could be a source of super-hot electrons.
- Published
- 2018
15. Linear transformer driven long pulse high power generator with higher repetition rate
- Author
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Jin Hui, Wang Gan-Ping, Luo Min, Xiang Fei, Zhang Yong-Hui, Kang Qiang, Cao Shao-Yun, Gong Shenggang, Tan Jie, Zhang Beizhen, Luo Guangyao, and Li Chun-Xia
- Subjects
Physics ,Long pulse ,Generator (computer programming) ,Repetition (rhetorical device) ,business.industry ,Electrical engineering ,General Physics and Astronomy ,business ,Power (physics) ,Transformer (machine learning model) - Abstract
The realization technique of modularization on the long pulse high power generator was expounded. The relation between the ferromagnetic dissipation of the linear transformer and the exciting magnetic current was analyzed. The main influential factors on the wave distortion from the primary pulse to the system output waveforms were discussed. Finally, through engineering experiments, a long pulse power electron beam of up to several gigawatt with repetition frequency of several dozen hertz and rise time of 40—50 ns was obtained. This paper gives a new idea for research on the modularization of the long pulse high power generator with higher repetition rate.
- Published
- 2010
16. Investigation on a long pulse relativistic extended interaction cavity oscillator
- Author
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Tan Jie, Jin Xiao, Luo Guangyao, Huang Hua, Luo Xiong, Zhang Beizhen, and Lei Lu-Rong
- Subjects
Physics ,Pulse repetition frequency ,Full width at half maximum ,Nuclear magnetic resonance ,Modulation ,General Physics and Astronomy ,Effective radiated power ,Atomic physics ,Pulse-width modulation ,Microwave ,Pulse (physics) ,Magnetic field - Abstract
The mechanism of modulation and rf extraction of an S-band on an injection locked, long pulse, relativistic extended interaction cavity oscillator (REICO) is studied in this paper by experiment, theory, and simulation. The origin of pulse shortening and mode competition of the REICO driven by the long pulse intense relativistic electron beams (IREBs) is explored. The modified structure of REICO with coupler is proposed for the first time, which suppresses the pulse shortening and mode competition remarkably. The pulse width of the modulated IREB is increased from 60 ns to 140 ns, and the magnitude of the modulated IREB is increased from 2 kA to 5 kA. The microwave radiation power and efficiency are promoted obviously after adjusting the parameters of the IREB and the leading magnetic field. Using a 580 kV, 48 kA, 210 ns electron beam with 11 T leading magnetic field, more than 400MW radiated power was extracted in 160 ns FWHM pulses at 289 GHz. The power efficiency is 27%, and the energy efficiency is 23%. The radiated power is 400 MW and the FWHM pulse is 184 ns when pulse repetition frequency of IREBs is 20 Hz. The experimental results are well consistent with the simulations. The injection locked REICO generates high power microwave of power 400 MW with pulse width 100 ns.
- Published
- 2010
17. Microsaccade direction reflects the economic value of potential saccade goals and predicts saccade choice.
- Author
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Yu G, Xu B, Zhao Y, Zhang B, Yang M, Kan JY, Milstein DM, Thevarajah D, and Dorris MC
- Subjects
- Adult, Animals, Female, Humans, Macaca mulatta, Male, Superior Colliculi physiology, Choice Behavior, Reward, Saccades
- Abstract
Microsaccades are small-amplitude (typically <1°), ballistic eye movements that occur when attempting to fixate gaze. Initially thought to be generated randomly, it has recently been established that microsaccades are influenced by sensory stimuli, attentional processes, and certain cognitive states. Whether decision processes influence microsaccades, however, is unknown. Here, we adapted two classic economic tasks to examine whether microsaccades reflect evolving saccade decisions. Volitional saccade choices of monkey and human subjects provided a measure of the subjective value of targets. Importantly, analyses occurred during a period of complete darkness to minimize the known influence of sensory and attentional processes on microsaccades. As the time of saccadic choice approached, microsaccade direction became the following: 1) biased toward targets as a function of their subjective value and 2) predictive of upcoming, voluntary choice. Our results indicate that microsaccade direction is influenced by and is a reliable tell of evolving saccade decisions. Our results are consistent with dynamic decision processes within the midbrain superior colliculus; that is, microsaccade direction is influenced by the transition of activity toward caudal saccade regions associated with high saccade value and/or future saccade choice., (Copyright © 2016 the American Physiological Society.)
- Published
- 2016
- Full Text
- View/download PDF
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