Effect of carbon nanofibres dispersion on the microwave absorbing properties of CNF/epoxy composites

In this investigation, double layer microwave absorbers are designed and developed with paired combination of 5 wt %, 7 wt %, 8 wt %, and 10 wt % expanded graphite-novolac phenolic resin (EG-NPR) composites, in the frequency range of 82–124 GHz The thickness and compositional combination of the two layers constituting the absorber are optimized to achieve minimum value of reflection loss (dB) and a broad microwave absorption bandwidth Double layer combinations showing −25 dB absorption bandwidth >2 GHz and −30 dB absorption bandwidth >1 GHz are chosen for fabrication The total thickness of the fabricated double layer microwave absorber is varied from 3 mm to 34 mm Absorption bandwidths at −10 dB, −20 dB, −25 dB and −30 dB are determined for the fabricated structure The maximum −25 dB and −30 dB absorption bandwidth of 247 GHz and 177 GHz, respectively, are observed for the double layer structure with (5 wt %–8 wt %) EG-NPR composites with total thickness of 32 mm, while −10 dB bandwidth c

Expanded graphite—Phenolic resin composites based double layer microwave absorber for X-band applications

Some embodiments include operation of an accelerator waveguide to accelerate particles to a first energy within the waveguide, wherein a prebuncher coupled to the waveguide outputs particle bunches having a first phase, change of a phase at which particle bunches will be output from the prebuncher from the first phase to a second phase, and operation of the accelerator waveguide to accelerate particles to a second energy within the waveguide, wherein the prebuncher outputs particle bunches having the second phase. Further aspects provide change of a resonant frequency of the prebuncher from a first frequency to a second frequency. According to still further aspects, the prebuncher includes a prebuncher cavity and change of the resonant frequency comprises change of a shape of the prebuncher cavity.

Multi-energy particle accelerator

Compact X-Band electron linac for radiotherapy and security applications

Design of a compact 12 MeV race-track microtron (RTM) is described. The results of operating wavelength choice, accelerating structure and end magnets optimization and beam dynamics simulation are represented. The use of a C-band linac and rare earth permanent magnet based end magnets permit to design RTM which is more compact and more effective as compared with the same energy circular microtron or linac. Electron beam with energy 6–12 MeV in 2 MeV step can be extracted from RTM. The estimated pulsed RF power required for feeding the linac is about 700 kW, total mass of accelerator is less than 40 kg and its dimensions are about 500x200x110 mm 3 .

https://epaper.kek.jp/e06/papers/wepch175.pdf

Design of 12 mev rtm for multiple applications

Most radiation therapy machines are based on microwave linear accelerators. The majority of medical accelerators use frequencies in the S-band range. Having a compact accelerator allows for a wide range of treatments. The size and weight of the accelerator is substantially reduced if a higher frequency is used. X-band frequencies are suitable for such applications. The X-band accelerator technology has been used in high-energy as well as industrial applications. In the radiation therapy field, it is already implemented in some machines. The Mobetron an Intra-Operative Radiation Therapy (IORT) treatment system is one example. Another example is the Stereotactic Radiosurgery machine, the CyberKnife. The compactness of these machines required the use of an X-band accelerator. The basis for choosing the X-band technology in some of the medical machines is analysed. A review of the exiting medical applications is included. We also discuss the availability of other X-band components in the machine, including high-power RF sources.

/pdf/applications-of-x-band-technology-in-medical-accelerators-3ur8hdyj77.pdf

S.M. Hanna

Papers

Applications of X-band technology in medical accelerators