2016年物理研究项目

埃米琳Douglas-Mann
指导老师:David Schaffner
部门:物理

脉冲形成网络的构造

A plasma gun source requires the construction of a pulse-forming network (PFN) of capacitors. 这个电路，由80个电路组成.5mF电容器和8个优化电感, would give an ideal pulse with just sufficient current for plasma ejection over an extended period of time. This would make it possible to generate sustained plasma injection for studying turbulence. 构建的第一阶段是使用LTSpice设计PFN, and use simulations of current over time to determine the optimal magnitudes and combination of inductances that result in a long pulse of constant current. After simulating the network, it will be possible to construct it in the laboratory. A typical appropriate combination of inductances is expected to result in a flat current pulse that lasts for almost 300 microseconds. 

科迪·费德勒·川口
导师:David Schaffner 
部门:物理

不锈钢接近实验

Current pulsed through a copper coil will generate a magnetic field. 当这种情况发生在不锈钢真空室内时, the resultant magnetic field will be modified due to Faraday’s law of induction. Using hall probes, as well as Bdot probes these effects can be measured.本研究的目的是探索这些影响, to help determine how to minimize the impact it has on the overall experiment. 此外, this information will help advance fusion research being conducted by Bryn Mawr in collaboration with Swarthmore's SSX lab. It is expected that as the distance between the copper coil and stainless steel chamber is increased, 对磁场的影响会减弱.

研究ers have yet to achieve a self-sustaining fusion reaction in which the amount of energy put in is less than that being produced. Bryn Mawr and Swarthmore  aim to develop new modules in which to accelerate and compress plasma plumes with relatively low energy input and high stability. Hall probes and Bdot probes are used to calculate the time of flight in order to know how fast the plasma is being accelerated. 不锈钢的使用既具有实用性, and cost efficient design that will be more accessible for future research.  

克莱尔·奥尔索普·夏纳，莱拉·法希姆，凯莉·菲利昂
Dr. 迈克尔·舒尔茨
物理

史瓦西时空中的黑洞灰体因子

The goal of our project is to calculate the greybody factor of black holes in Schwarzchild spacetime. Black holes radiate the full thermal spectrum near the event horizon, and the amount that the observed radiation differs from this perfect spectrum is referred to as the greybody factor. The radiation created at the event horizon is referred to as Hawking radiation and is a result of quantum effects. Only a small portion of the Hawking radiation that is created will travel past the event horizon, 很大程度上是由于黑洞周围的极端几何形状. Our research will focus on determining how much of the Hawking radiation created at the event horizon will travel outwards to infinity, i.e. how much will be able to tunnel out of the event horizon into the space beyond. 为了确定这个, we will calculate the effective potential utilizing the Klein-Gordon Equation in Schwarzchild spacetime and then we will calculate transmission coefficient and the potential of tunneling through this potential. Calculating the tunneling potential and how the radiation at infinity differs from the perfect thermal spectrum emitted helps us further our understanding about black holes and their radiation. 这也适用于全息原理. 

海莉约翰逊
大卫·沙夫纳教授
物理

不锈钢接近实验

Generating and accelerating plasma in a conductive stainless steel chamber affects the magnetic fields inside, 根据法拉第感应定律. These effects will interfere with measurements of the magnetic field due to a pulsed coil (which will later be used to accelerate plasma) inside the chamber. This work is being done in conjunction with work at the Swarthmore Spheromak Experiment, 哪个用的是玻璃腔而不是不锈钢腔. Both facilities are attempting to efficiently accelerate and compress plasma for the long-term goal of fusion technology as part of the project for Accelerating Low-Cost Plasma Heating and Assembly (ALPHA). Initial determinations of the effect of the stainless steel chamber will be made by using a B-dot probe to measure the magnetic field of a pulsed coil placed at incremental distances from a stainless steel plate. 当线圈远离极板时, the plate’s interference with the magnetic field is expected to lessen. 初步的数据显示，距离很近, the plate’s effects may be drastic enough to reverse the coil’s magnetic field entirely.

刘志敏(Cheryl)和林嘉怡(Rose)
导师:Michael Noel
物理系

Investigating the Interactions among Ultracold Rubidium Atoms in Rydberg States

Rubidium atoms cooled to a velocity near zero and trapped at a certain location in space can be excited to high lying Rydberg States with a system of tunable diode lasers. 这些原子有很强的偶极矩, 并且可以通过偶极-偶极相互作用交换能量.

The laser beams from the diode lasers are tuned to the appropriate wavelength and locked with circuits. Lasers operating at 780nm are used to cool and trap atoms in a magneto-optical trap (MOT). 另外两个二极管激光器(766nm), 1265nm), are tuned to excite the Ultracold Rubidium atoms from the 5p3/2 state to the 5d5/2 state, 最后到达np3/2d状态(里德堡状态).

Our laboratory was recently moved so we will focus on rebuilding the previous laser system and MOT in the new laboratory. 等到整个系统有效运转的时候, we will start to observe the trapped Ultracold Rubidium atoms and to investigate their interactions.