Fusion plasmas promise clean energy. For its eventual realization, it is essential to visualize turbulent structures accurately and timely. Microwave reflectometry is a radar technique used to infer the electron density characteristics by probing the density-dependent cutoff layer in plasmas. Microwave Imaging Reflectometry (MIR), which was conceived by Dr. Mazzucato of the Princeton Plasma Physics Laboratory, is a technique in which large-aperture optics at the plasma edge are used to collect as much of the scattered wavefront as possible and optically focus an image of the cutoff layer onto an array of detectors, thus restoring the integrity of the phase measurement. For more details regarding MIR, please visit Prof. Neville Luhmann’s and Prof. Ernesto Mazzucato’s lab websites.
We are leveraging CMOS based IC approaches to develop miniaturized MIR systems. As the first step, we are developing the MIR CMOS transmitter, as shown in the Figure below. To allow simultaneous detection of multiple fluctuations, simultaneous multiple frequency tones are launched with each frequency reflecting from a different density-dependent cutoff layer. A wide frequency range of 55 GHz to 75 GHz is required. The challenge of multiple frequency generation from one transmitter is the large peak to noise ratio (PAR) limiting the output power of each tone to Pout/N^2 for linear operation. To overcome this issue, the transmitter allocates 2 frequency tones per channel and generates 8 tones simultaneously with 4 parallel channels. This offers the advantages of reducing system complexity by removing quadrature LO generation, high efficiency power combining by using diplexer based combiner structure.
- Y. Wang, B. Tobias, Y.-T. Chang, J.-H. Yu, M. Li, F. Hu, M. Chen, M. Mamidanna, T. Phan, A.-V. Pham, J. Gu, X. Liu, Y. Zhu, C.W. Domier, L. Shi, E. Valeo, G.J. Kramer, D. Kuwahara, Y. Nagayama, A. Mase, and N.C. Luhmann Jr, “Millimeter-wave imaging of magnetic fusion plasmas: technology innovations advancing physics understanding,” vol. 57, Nuclear Fusion, March 2017
- Y.-T. Chang, Y. Ye, H. Xu, Q. J. Gu, C. Domier, and N. C, Luhmann, Jr., “A Ultra-Wideband CMOS PA with Dummy Filling for Reliability,” Elsevier Solid State Electronics, pp.125-133, March 2017
- Y.-T. Chang, Y. Ye, Q. J. Gu, C. Domier, and N.C. Luhamnn, Jr “The V-Band CMOS Multi-Frequency Transmitter for Plasma Imaging Radar Reflectometric Diagnostic,” IEEE International Microwave Symposium 2016
- Y.-T. Chang, Y. Ye, C. Domier, and Q. J. Gu, “A Ultra-Wideband CMOS PA with Dummy Filling for Reliability,” 2015 IEEE International Wireless Symposium