Frequency and mode measurement techniques for megawatt-class gyrotrons

State-of-the-art vacuum electron tubes such as gyrotrons, deliver RF output powers up to more than 2 MW at frequencies up to 170 GHz. In terms of the very high power levels, a proper verification of the gyrotron components itself and measurements during gyrotron operation are vital to prevent possible fatal errors. Several basic RF measurement setups, which are used at IHM/KIT, are discussed. Currently, their upper frequency limit is 175 GHz. In terms of future gyrotron operation above 200 GHz, upgrades of the measurement setups for operation up to 260–330 GHz are prepared. The experimental devices discussed herein are a quasi-optical mode generator for the verification of the quasi-optical gyrotron output system, the window measurement test stand to verify the ceramic gyrotron output window and the frequency diagnostic system to measure the operating frequency and thereby the excited mode.

Measurement of the electron beam energy in a source with a plasma anode and the beam extraction into the atmosphere through a foil window

Measurements of the energy of an electron beam in an electron beam source with an explosive-emission cathode, a plasma anode and a foil window, providing the extraction of an electron beam with a cross-section of (100–200) cm2 into the atmosphere, have been performed. The high voltage source was a Marx generator based long lines with matched loads. The energy values were calculated from the results of measurements of the temperature of a beam collector placed in vacuum using thermistors and an infrared imager. At an accelerating voltage of ~ 200 kV, a current of (1–2) kA, and an electron beam duration of 5 μs, the maximum values of the energy released in the collector with a cross section of 74 cm2 were (650–850) J/pulse. A decrease in the current and energy of the beam was recorded approximately by a factor of two after passing through an AMG-2n aluminum-magnesium foil with a thickness of 30 μm. The use of infrared imager for recording the beam structure in the plane of the output window in air has been tested.

Análise de falhas e efeitos na preparação e dispensação de quimioterápicos

Objetivo: Realizar un Análisis Multimodal de fallas y efectos para identificar prospectivamente los riesgos relacionados a la fase de la preparación y dispensación de medicamentos quimioterápicos en una unidad ambulatoria de un centro de referencia en oncología. Métodos: Se utilizaron las seis primeras etapas del Análisis Multimodal de fallas y Efectos: identificar las situaciones peligrosas y montar un equipo; definir el proceso a ser analizado describiendo gráficamente; aplicar lluvia de ideas buscando identificar modos de fallas; priorizar los modos de fallas y realizar análisis de riesgos; identificar las causas potenciales de los modos de fallo y volver a dibujar el proceso. Resultados: Se identificaron diecisiete modos de falla, siendo dos clasificados como de alto riesgo: cambiar la ventana de salida del medicamento y cálculo erróneo de la dosis de medicamento intratecal. Conclusiones: Se identificaron los posibles modos de falla que se relacionaban al proceso analizado, además, fue posible definir causas potenciales para la existencia de esos riesgos. Aim: Conduct a Failure Mode and Effect Analysis (FMEA) to prospectively identify the risks related to the preparation and dispensation of chemotherapy drugs at an outpatient unit of a reference center in oncology. Methods: The first six stages of Failure Mode and Effect Analysis were used to identify dangerous situations and assemble a team; define the process to be analyzed and describe it graphically; apply a host of ideas to identify failure modes; prioritize failure modes and conduct risk analysis; identify potential causes of failure modes and redesign the process. Results: Seventeen failure modes were identified, two of which were classified as high risk: changing the output window for the drug and miscalculating the intrathecal drug dose. Conclusions: The possible failure modes related to the process analyzed were identified; in addition, it was possible to define potential causes of these risks.

Комбинированные окна для газовых лазеров высокой мощности

Based on the previously developed mathematical model of the behavior of the multi-kilowatt laser window with an unstable cavity, the case of a two-component output window is considered. The two-component window consists of a transparent polycrystalline diamond ring and a central opaque area separated by a plastic vacuum gasket. The central opaque area is equipped with a cryoaccumulator to reduce heat load. Numerical calculations of thermomechanical processes are performed for such windows used in high-power CO2 lasers. Mathematical model used for the calculations consists of three parts - thermophysical, mechanical and optical. The advantages of using a two-component design with a cryoaccumulator under the conditions of a gas laser operating in the multi-kilowatt power range are demonstrated. The dependences of the maximum output power, temperature distribution and mechanical stresses versus the thickness of the window are obtained. The optimal conditions providing maximum radiation strength and minimum beam divergence are considered.