A Beam Position Monitor (BPM) is potentially useful to measure the position and phase of the beam in air in a non-destructive way. An air-gap BPM in experiments, such as beam-induced radioactive waste management and dynamic radiography applications, where a so-called air gap is needed, can be utilized to measure the beam position and phase. In this study, a stripline BPM was used in the air-gap of an 800 MeV proton beam transport line. The downstream end of the primary beamline exit window was made of a thin aluminum plate and allowed the beam to travel 1.2 m in ambient air before re-entering into a vacuum drift section. Such a configuration was arranged to examine the BPM effectiveness in atmospheric temperature and pressure where ionization of air occurs. In this study, a high energy (800 MeV), high current (0.6 A beam peak current/pulse) proton beam of 5 mm radius was transported in the air. The beam position relative to the axis was measured by detecting the signature of the beam in a nanosecond scale. This nanosecond scale detection ability was useful to identify other signals such as plasma effects. The BPM signals were processed at a frequency of 201 MHz; thus, one gets a stronger response in a stripline pattern as it was used in this study instead of a dot-type BPM. Experimental data show that the BPM works well in air, but ionization of air or plasma formation could not be measured over the BPM signal. The design, construction, and performance of a BPM in air environment are presented.

中文翻译：

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使用BPM测量空气中的质子束位置

光束位置监控器（BPM）潜在地可用于以无损方式测量光束在空气中的位置和相位。实验中的气隙BPM（例如，束流诱发的放射性废物管理和动态射线照相应用）需要使用所谓的气隙来测量束流的位置和相位。在这项研究中，在800 MeV质子束传输线的气隙中使用了带状线BPM。主光束线出射窗的下游端由一块薄铝板制成，允许光束在环境空气中传播1.2 m，然后重新进入真空漂移区。布置这种配置以检查在发生空气电离的大气温度和压力下的BPM有效性。在这项研究中，高能量（800 MeV），高电流（0。6在空气中传输了半径为5 mm的束峰电流/脉冲质子束。通过以纳秒标度检测光束的特征来测量相对于轴的光束位置。这种纳秒级检测能力可用于识别其他信号，例如等离子体效应。BPM信号以201 MHz的频率处理；因此，如本研究中所使用的那样，人们在带状线模式中获得了更强的响应，而不是点式BPM。实验数据表明，BPM在空气中工作良好，但无法在BPM信号上测量到空气的电离或等离子体的形成。介绍了空气环境中BPM的设计，构造和性能。这种纳秒级检测能力可用于识别其他信号，例如等离子体效应。BPM信号以201 MHz的频率处理；因此，如本研究中所使用的那样，人们在带状线模式中获得了更强的响应，而不是点式BPM。实验数据表明，BPM在空气中工作良好，但无法在BPM信号上测量到空气的电离或等离子体的形成。介绍了空气环境中BPM的设计，构造和性能。这种纳秒级检测能力可用于识别其他信号，例如等离子体效应。BPM信号以201 MHz的频率处理；因此，如本研究中所使用的那样，人们在带状线模式中获得了更强的响应，而不是点式BPM。实验数据表明，BPM在空气中工作良好，但无法在BPM信号上测量到空气的电离或等离子体的形成。介绍了空气环境中BPM的设计，构造和性能。但是无法通过BPM信号测量空气的电离或等离子体的形成。介绍了空气环境中BPM的设计，构造和性能。但是无法通过BPM信号测量空气的电离或等离子体的形成。介绍了空气环境中BPM的设计，构造和性能。