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Chou, C. K.

Publications and source records attributed to Chou, C. K..

12 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2003

Simplified Formulae System for Resonant Inverse Compton Scattering of a Fast Electron in an Intense Magnetic Field

We present simple analytical formulae for the emission spectrum and total power of a special kind of resonant inverse Compton scattering (RICS) of a relativistic electron in an intense magnetic field. In contrast with the available formulae system, we obtain a markedly simplified one based on the semiclassical quantum theory, which is more understandable for people who are unfamiliar with quantum electrodynamics. We show that the RICS process, under an appropriate 'accommodation condition' derived in this paper, is predominantly much more efficient than the coexistent ordinary inverse Compton scattering, and produces highly beamed high-frequency radiation with moderately good monochromaticity. Our formulae are simple to use - thus offering a lucid physical intuition for the theory - and may find wide applications in hard X-ray and gamma-ray astrophysics.

You, J. H.↗
NASA NTRS1993

Numerical modeling for an electric-field hyperthermia applicator

Hyperthermia, in conjunction with radiation and chemotherapy for treatment of cancers, is an area of current concern. Experiments have shown that hyperthermia can increase the potency of many chemotherapy drugs and the effectiveness of radiation for treating cancer. A combination of whole body or regional hyperthermia with chemotherapy or radiation should improve treatment results. Conventional methods for inducing whole body hyperthermia, such as exposing a patient in a radiant cabinet or under a hot water blanket, conduct heat very slowly from the skin to the body core. Thus a more efficient system, such as the three-plate electric-field hyperthermia applicator (EHA), is developed. This three-plate EHA has one top plate over and two lower plates beneath the patient. It is driven at 27.12 MHz with 500 Watts through a matching circuit. Using this applicator, a 50 kg pig was successfully heated to 42 C within 45 minutes. However, phantom and animal studies have indicated non-uniform heating near the side of the body. In addition, changes in the size and distance between the electrode plates can affect the heating (or electromagnetic field) pattern. Therefore, numerical models using the method of moments (MOM) or the finite difference time domain (FDTD) technique are developed to optimize the heating pattern of this EHA before it is used for human trials. The accuracy of the numerical modeling has been achieved by the good agreement between the MOM and FDTD results for the three-plate EHA without a biological body. The versatile FDTD technique is then applied to optimize the EHA design with a human body. Both the numerical and measured data in phantom blocks will be presented. The results of this study will be used to design an optimized system for whole body or regional hyperthermia.

Wu, Te-Kao↗
NASA NTRS1979

Photoneutrino reactions in a superstrong magnetoactive plasma

The neutrino luminosity due to the photoneutrino process in the presence of a superstrong magnetoactive electron plasma appropriate for neutron stars is computed. The results indicate that for relatively low temperatures, between 100 million and 500 million K, the energy loss rate is significantly reduced both in the low-density regime below about 10 million g/cu cm (by the magnetic field) and in the high-density regime above that value (by plasmon excitations). These effects are temperature dependent, and they are less pronounced when the temperature is in the range from 500 million to 1 billion K.

Chou, C. K.↗
NASA NTRS1974

Neutrino reactions in strong magnetic field

Presentation of the energy losses due to several neutrinos processes: (1) synchrotron neutrinos, (2) pair annihilation neutrinos, (3) plasmon neutrinos, and (4) photoneutrinos in the presence of a superstrong magnetic field. Numerical results are tabulated and illustrated for several values of densities and temperatures. In the low density regime, the presence of a magnetic field decreases the luminosity, whereas the opposite is true at higher densities. This last effect is, however, almost entirely due to the existence of a new process, the synchrotron neutrinos that disappear when H goes to zero. Even though the overall effect can only be quantitatively ascertained after a complete cooling computation is performed, one should however expect a much lower temperature for neutron star surface than the one computed in the case where H is zero.

Canuto, V.↗
NASA NTRS1965

The Vlasov equations

Vlasov equations studies and applications of statistical mechanics to plasma dynamics

VLASOV EQUATION↗