Abstract. Chamber clocks are weight-driven wall clocks and the first type of domestic clocks to be widely used in the home. During the 16th and 17th centuries, although horologists in Europe made various types of chamber clocks in large numbers, many of the clocks have since been either replaced or discarded. In this study, we used the method of mechanical evolution and variation, analyzed and compared clock movements based on historical data and existing clocks, and synthesized all possible movement configurations of early-day chamber clocks. A total of 4 going-train configurations and 10 striking-train configurations were identified, making a total of 40 feasible movement configurations. In addition, 14 existing representative chamber clocks were selected as examples to illustrate the above configurations and their variations, which enabled the creation of a comprehensive atlas of the movement designs. The results of the study can not only help to systematically carry out the reconstruction design of various chamber clocks, but also provide new information for scholars of history of science to further historical research and develop new materials for creativity as well as science and technology education.

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Harmonic multiplying gyrotron traveling-wave amplifiers (gyro-TWAs) permit for magnetic field reduction and frequency multiplication. A high-order-mode harmonic multiplying gyro-TWA with large circuit dimensions and low ohmic loss can achieve a high average power. By amplifying a fundamental harmonic TE01 drive wave, the second harmonic component of the beam current initiates a TE02 wave to be amplified. Wall losses can suppress some competing modes because they act as an effective sink of the energy of the modes. However, such wall losses do not suppress all competing modes as the fields are contracted in the copper section in the gyro-TWA. An improved mode-selective circuit, using circular waveguides with the specified radii, can provide the rejection points within the frequency range to suppress the competing modes. The simulated results reveal that the mode-selective circuit can provide an attenuation of more than 10 dB to suppress the competing modes (TE21, TE51, TE22, and TE03). A G-band second harmonic multiplying gyro-TWA with the mode-selective circuit is predicted to yield a peak output power of 50 kW at 198.8 GHz, corresponding to a saturated gain of 55 dB at an interaction efficiency of 10%. The full width at half maximum bandwidth is 5 GHz.

Harmonic multiplying gyrotron traveling-wave amplifiers (gyro-TWAs) allow for magnetic field reduction and frequency multiplication. To avoid absolute instabilities, this work proposes a W-band harmonic multiplying gyro-TWA operating at low-order modes. By amplifying a fundamental harmonic TE 11 drive wave, the second harmonic component of the beam current initiates a TE 21 wave to be amplified. Absolute instabilities in the gyro-TWA are suppressed by shortening the interaction circuit and increasing wall losses. Simulation results reveal that compared with Ka-band gyro-TWTs, the lower wall losses effectively suppress absolute instabilities in the W-band gyro-TWA. However, a global reflective oscillation occurs as the wall losses decrease. Increasing the length or resistivity of the lossy section can reduce the feedback of the oscillation to stabilize the amplifier. The W-band harmonic multiplying gyro-TWA is predicted to yield a peak output power of 111 kW at 98 GHz with an efficiency of 25%, a saturated gain of 26 dB, and a bandwidth of 1.6 GHz for a 60 kV, 7.5 A electron beam with an axial velocity spread of 8%. V C 2012 American Institute of Physics. [http://dx.

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