A gyrotron is a vacuum tube that converts the kinetic energy of the gyro motion of electrons into microwave energy. The University of Tokyo has developed the UT-94 gyrotron with a power of 600 kW, a frequency of 94 GHz, and a pulse length of 100 microseconds for the purpose of thrust generation experiments of Microwave Rockets. In order to suppress arcing in the vacuum tube, which has been an obstacle to the power increase and multi-pulse oscillation, the vacuum has been improved by introducing an ion pump and by reducing outgassing with the low-voltage ageing operation. As a result, an oscillation with estimated output of 100 kW and a 1 kHz multi-pulse oscillation were achieved.

  In the pattern measurement of the SPS demonstration satellite in low earth orbit, a two-dimensional pattern is measured using the movement of the satellite by placing multiple receiving stations in a straight line on the ground. The measured patterns are reconstructed using the two-dimensional least-squares method in order to exclude errors in the receiving stations. In order to measure the two-dimensional pattern up to the first sidelobe of the array antenna, we attempted to consider an approximation function, which provides a better least-squares approximation of the pattern of the circular antenna. Also, since the shape of the 2D pattern of the antenna varies with the antenna's external shape, we compared the circular and square array antennas, derived a function suitable for reconstructing the pattern including the sidelobes, showed the dependence of the approximation function and the receiving station configuration, and obtained guidelines for more accurate pattern measurement.

  Currently, a Space Solar Power System (SSPS) is being considered. In preparation, a small test satellite is planned to be launched. This satellite serves as a demonstration satellite for the verification of precise control of the transmit antenna beams required for SPS. Therefore, to reproduce the shape of the beam, we are considering installing multiple receiving stations on the ground for measurement. In this paper, we developed a receiver corresponding to the test satellite, estimated the one-dimensional antenna pattern, and measured the level difference between the two receivers. We show that this method is useful and consider its application to test satellites.

  Solar Power Satellite (SPS) requires the construction of large-scale structures, such as antennas and solar array paddles in space. This paper describes a comparison of the two deployment methods. One is the deployment and rendezvous docking method. Rendezvous docking will be performed after the synchronous deployment of many panels in orbit. The other is the platform method. This method builds a platform with robots in orbit. The robots unfold the panels and connect them on the platform. In addition, the results of mechanical analysis to confirm the behavior of the platform when supplying and deploying the panel to the platform is explained.

  In Tethered solar power satellite on GEO, changes in the angle of the sunlight cause changes in the amount of power generated by solar cells. These variations result in changes in the DC-RF conversion efficiency of RF power amplifiers. This variation of the DC-RF conversion efficiency has been estimated in a previous study by using prototypes of the RF amplifiers. This estimated variation of the DC-RF conversion efficiency must be suppressed. This paper reports a new method to maintain high power efficiency during the variation of the power supply by applying the pulse modulation for RF amplifier.

  At the SSPS workshop, we examined the feasibility of various SSPS systems that have been proposed so far. Since May 2021, the workshop has been held online almost every month and is the second year. From the main contents of the discussion, points to note about array antennas, a test satellite launched by the California Institute of Technology, examination of Japanese test satellites, problems with the sandwich method, pilot signals, and three invited lectures will be introduced.