The author recently noticed that noise not only contaminates signals, but also heats electronic circuits. This new viewpoint suggests a reason why lithium-ion batteries of a sophisticated new aircraft, Boeing 787, encountered overheating, or caught fire, because conventional electronic circuits could produce enough noise to heat circuit elements. In order to overcome this issue concerning the DC-line system of the AC-DC converter, it has been practically and theoretically proven that a symmetric three-line (S3L) circuit with both common- and normal-mode filters is excellent for noise reduction. On the other hand, the author identified a common-mode noise in addition to the normal-mode noise at an AC line, several years ago. In order to overcome such problems of an AC-line system as those of a DC-line system, the author recommends the symmetrization and a common-mode filter for the AC-line system of an AC-DC converter. This paper describes how both common- and normal-mode noises could heat electronic circuits based on calculations of three-line circuit theory. Heating occurs along with the coupling of common- and normal modes of a propagation wave type and the reflection of both waves at circuit elements, causing complicated phenomena beyond our understanding based on the conventional circuit theory.

For linear colliders, extremely small and stable beam is required for high luminosity. At ILC (International Linear Collider), designed vertical beam size and required vertical position stability at the interaction point is nanometer level. For confirming feasibility of such small and stable beam, a prototype of the final focus system of ILC was constructed as an extension of ATF (Accelerator Test Facility) at KEK. This uses small emittance beams produced in and extracted from the damping ring of ATF. The project of final focus system study is called ATF2. One of the most important issues in squeezing beam is chromatic aberration, aberration caused by energy spread of beam. We have demonstrated the local chromatic correction method, which will be used for ILC, and observed the vertical beam size about 44 nm with low intensity beam.

We have upgraded both the beam energy (400 MeV) and the peak beam current (50 mA) of the J-PARC linac to realize the nominal performance of 1 MW at the 3 GeV Rapid Cycling Synchrotron (RCS) and 0.75 MW at the 30 GeV Main Ring synchrotron (MR). For the energy upgrade, we installed an Annular-ring Coupled Structure linac (ACS) and 972 MHz klystron system during the summer shutdown of 2013. The result of the beam test showed the beam loss at the RCS beam injection area decreased significantly by increasing the energy. For the beam current upgrade, we replaced the ion source, the RFQ and the RF chopper system during the summer shutdown of 2014. The beam commissioning was started in September 2014, and the 1 MW equivalent beam operation was successfully demonstrated at the RCS in January 2015.

In order to remove problems induced by serious accelerator activation around the stripping foil, J-PARC RCS should be converted to a 3-GeV compressor ring, installing laser stripping. Activation due to nuclear scattering by stripping foil seems to be as serious as anticipated at the MW beam power level. As the beam loss due to nuclear scattering is unavoidable, foil stripping should be replaced to laser stripping at the most fruitful injection energy of H^- beam that is 3-GeV, upgrading the linac energy.

P3 WS (Photocathode Physics for Photoinjector Workshop) was held in LBNL (Laurence Berkeley National Laboratory), Berkeley, California, US from Nov. 3. to 5. 2014. This is the third of the WS series which had been started in 2010 at BNL (Brookhaven National Laboratory). The WS has been held once in every two years and the second WS was at Cornell University. In the modern accelerators, the linac becomes more important because various advanced beams which are not possible in Synchrotron can be accelerated. In the modern linac, photo-cathode is one of the most critical devices which sometimes determines the accelerator performance. In the WS, photocathode and related physics were discussed from the accelerator point of view. However, not only the accelerator physicists, but also many material and condensed matter physicists attended the WS. This is a new trend in the Photocathode studies which reflects the essential role of the Photocathode in the advanced accelerators. The WS is briefly reported.