Non-thermal tumor ablation technology based on short pulse strong electric field can overcome the defects of thermal ablation and cryoablation, which provides a new opportunity for the development of tumor therapy. In this study, the CAEP terahertz free electron laser facility was preliminarily used to do the research on non-thermal tumor ablation method because of its unique macro-micro pulse time series. The biological effects of short pulse strong field terahertz radiation on melanoma cells and tissues were studied in vitro and in vivo. In vitro experiments show that the survival rate of tumor cells is significantly different after being irradiated by different frequency, power, and radiation duration of terahertz wave. Strong field terahertz wave can inhibit the proliferation of tumor cells. In vivo experiments showed that compared with the control group, the tumor tissue proliferation of the irradiated experimental group was slowed down, the tumor volume was gradually reduced, and the strong field terahertz pulses could inhibit the growth of tumor tissue. These preliminary results will provide a feasible reference for further research and long-term clinical application.
China Academy of Engineering Physics Terahertz Free Electron Laser (CTFEL) has been commissioned in 2017 and provides 0.7~4.2 THz wave for users. In order to cover the frequency range of 0.1~0.7 THz, a super-radiation terahertz source is designed behind CTFEL. In this paper, design of the super-radiation source is reported. The super-radiation source works with MeVs and sub-picosecond electron bunch. The technical route to generate MeVs and sub-picosecond is as follows: the superconducting accelerator of CTFEL has two independent 4-cell cavities, the electron beam is accelerated in the first 4-cell cavity, and compressed in the second 4-cell cavity. The sub-picosecond electron beam travels through a undulator with a period of 58 mm to generate terahertz wave, and the gap of the undulator is adjusted to cover the frequency range of 0.1~0.7 THz. The theoretical calculation shows that average power of the super-radiation source can reach tens of Walt.
At present the SASE3 undulator line at the European XFEL is using a planar undulator producing linear polarized soft Xray radiation only. In order to satisfy the demand for circular polarized radiation a helical undulator system, the so-called afterburner is in construction. It will be operated as a radiator using the pre-bunched beam of the SASE3 undulator system. Among several options for the magnetic structure the Apple-X geometry was chosen. This is a pure permanent magnet undulator using NdFeB material. Four magnet arrays are arranged symmetrically the beam axis. Polarization can be changed by adjusting the phase shift (PS) between the two orthogonal structures. The field strength can be adjusted either by gap adjustment or alternatively by the amplitude shift (AS) scheme. For an engineering design the maximum values of forces and torques on each of the components under worst case operational conditions are important. The superposition principle is used to reduce calculation time. It is found that the maximum forces Fx, Fy and Fz for a 2m long Apple-X undulator are 1.8*104N, 2.4*104N and 2.3*104N, respectively. More results are presented in this paper.
At present the SASE3 undulator beamline of the European XFEL includes 21 planar undulators which generate
horizontally polarized radiation in the soft X-ray region between 0.4 and 5.0nm. In order to satisfy the demand to full
polarization control it is planned to install four helical undulator segments at the end of the planar SASE3 undulator
system. The helical undulator segments will be used as an afterburner, i.e. they will use the micro-bunched electron beam
and produce enhanced coherent radiation at a power level comparable to the linear system but with full polarization
control. In this contribution the properties of the emitted radiation will be investigated.
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