Small-Scale Solar Magnetic Fields

As we resolve ever smaller structures in the solar atmosphere, it has become clear that magnetism is an important component of those small structures. Small-scale magnetism holds the key to many poorly understood facets of solar magnetism on all scales, such as the existence of a local dynamo, chromospheric heating, and flux emergence, to name a few. Here, we review our knowledge of small-scale photospheric fields, with particular emphasis on quiet-sun field, and discuss the implications of several results obtained recently using new instruments, as well as future prospects in this field of research.     

High precision composite pipes for SOLAR-B optical structures

The authors have been developing new high thermal conductivity and low moisture absorption composite pipes for high precision space optics applications on the Japanese Institute of Space and Astronautical Science (ISAS) SOLAR-B satellite.Pitch based K13C (Mitsubishi Chemical) high modulus and high conductivity graphite fiber, and EX1515 (Bryte Technology) low moisture absorption cyanate resin, were applied to the pipes.Thermal expansion of the composite pipes was designed to be zero and more uniform in the longitudinal direction in order to obtain long term dimensional stability in the space environment.Model pipes whose length was 500 mm were fabricated and evaluated for thermal and hygroscopic deformation in a new testing apparatus. Equivalent coefficient of thermal expansion of the model pipes was essentially zero (less than 0.1 ppm/°C) and standard deviation of these coefficients was 0.05 ppm/°C. Hygroscopic deformation of the model pipes was under representative conditions 7 ppm over 3 month. The excellent thermal and hygroscopic stability were verified. In addition, thermal conductivity of the model pipes was more than 200 W/(m · K).