Dataset Information

Broadband terahertz-power extracting by using electron cyclotron maser.

ABSTRACT: Terahertz applications urgently require high performance and room temperature terahertz sources. The gyrotron based on the principle of electron cyclotron maser is able to generate watt-to-megawatt level terahertz radiation, and becomes an exceptional role in the frontiers of energy, security and biomedicine. However, in normal conditions, a terahertz gyrotron could generate terahertz radiation with high efficiency on a single frequency or with low efficiency in a relatively narrow tuning band. Here a frequency tuning scheme for the terahertz gyrotron utilizing sequentially switching among several whispering-gallery modes is proposed to reach high performance with broadband, coherence and high power simultaneously. Such mode-switching gyrotron has the potential of generating broadband radiation with 100-GHz-level bandwidth. Even wider bandwidth is limited by the frequency-dependent effective electrical length of the cavity. Preliminary investigation applies a pre-bunched circuit to the single-mode wide-band tuning. Then, more broadband sweeping is produced by mode switching in great-range magnetic tuning. The effect of mode competition, as well as critical engineering techniques on frequency tuning is discussed to confirm the feasibility for the case close to reality. This multi-mode-switching scheme could make gyrotron a promising device towards bridging the so-called terahertz gap.

SUBMITTER: Pan S

PROVIDER: S-EPMC5544717 | biostudies-literature | 2017 Aug

REPOSITORIES: biostudies-literature

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Broadband terahertz-power extracting by using electron cyclotron maser.

Pan Shi S Du Chao-Hai CH Qi Xiang-Bo XB Liu Pu-Kun PK

Scientific reports 20170804 1

Terahertz applications urgently require high performance and room temperature terahertz sources. The gyrotron based on the principle of electron cyclotron maser is able to generate watt-to-megawatt level terahertz radiation, and becomes an exceptional role in the frontiers of energy, security and biomedicine. However, in normal conditions, a terahertz gyrotron could generate terahertz radiation with high efficiency on a single frequency or with low efficiency in a relatively narrow tuning band. ...[more]

PMID: 28779113

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Project description:We report that terahertz (THz) irradiation of mouse mesenchymal stem cells with a pulsed broadband (centered at 10 THz) source, or a single-frequency, 2.52 THz, (SF) laser source, both with weak average power (<1mW/cm2), results in specific heterogenic changes in gene expression. The insignificant differential expression of heat shock and stress related genes as well as our temperature measurements imply a non-thermal response. The microarray survey and RT-PCR experiments demonstrate that at different irradiation conditions distinct groups of genes are activated. Stem cells irradiated for 12 hours with the broadband THz source exhibit an accelerated differentiation toward adipose phenotype, while the 2-hour (broadband or SF) irradiation affects genes transcriptionally active in pluripotent stem cells. Phenotypic and gene expression differences suggest that the THz effect depends on irradiation parameters such as duration and type of THz source, and on the level of stem cell differentiation. Computer simulations of the core promoters of two pluripotency markers reveal association between gene upregulation and propensity for DNA breathing. We propose that THz radiation has potential for non-contact control of cellular gene expression. Growing in petri dish mouse mesenchymal stem cell cultures are irradiated for 12 hours with pulsed ultrafast (35 fs) broadband (centered at ~10 THz) source. Three independent biological experiments were conducted. In each experiment, a control mMSC culture was placed adjacent to the irradiated sample, and the temperature was kept at 26-27M-BM-:C for both the control and the irradiated sample. Immediately after completing the irradiation, total RNA was extracted from the irradiated sample and the control, and microarrays were used to identify differential changes in gene expression between the irradiated sample and its respective control. In each experiment, the mMSC cultures were synchronized to be at the same differentiation time point immediately before the irradiation.

Dataset Information

Broadband terahertz-power extracting by using electron cyclotron maser.

Publications

Broadband terahertz-power extracting by using electron cyclotron maser.

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