‘Clean’ bombs: Nuclear technology and nuclear strategy in the 1950s

The idea of ‘clean’ bombs, nuclear weapons with a reduced amount of radioactive fallout resulting from their fission part, has met much ridicule since its public inauguration in 1956. Many scholars have regarded the bombs as a propaganda tool, stopping short of analyzing their role in the transformative phase of US nuclear strategy in the 1950s. This paper reexamines the clean bomb episode through 1958, shedding light upon the dynamic relationship between the development of nuclear weapons technology and the evolution of nuclear strategy from massive retaliation to flexible response. It also discusses the mechanism and momentum of nuclear weapons technology innovation until the US suspended nuclear testing in late 1958.     

室温下单电子晶体管3种临界尺寸的确定

为使单电子晶体管达到实际应用的地步,开展室温条件下相关研究成为必然。从正统理论出发,推导、计算出室温条件下单电子晶体管能否正常工作的库仑岛临界尺寸:存储器件为6.5nm,逻辑器件为1.5nm;本文还推导和计算出单电子晶体管室温下发生能量量子化效应的临界尺寸:4.7nm,并对这3种临界尺寸进行了验证和分析。另外,通过比较分析本文还得出了室温条件下,所有逻辑器件均必须考虑能量量子化效应,所有存储器件应尽量考虑能量量子化效应的结论。分析结果表明,库仑岛临界尺寸的确定对单电子晶体管的实际应用具有重要意义。     

动态点对点通信天线的自动控制研究

在相对运动平台的点对点通信中,天线如何快速、准确地进行跟踪对准是接收高质量通信信号的保证.针对于动态点对点通信中定向天线对准难的问题,提出了一种基于坐标跟踪法和信号跟踪法的联合天线跟踪控制法,并对此方法进行了系统的软、硬件设计.通过精度分析和试验得出该方法对准精度高,系统易于实现,能够满足微波通信天线对准工程实现中的快与准的要求.     

超低轨道卫星摄动特性分析及轨道维持方法

针对超低轨道卫星长时间在轨飞行的轨道维持问题,分析了超低轨道平均偏心率矢量变化特性,提出了一种超低轨道维持的控制方法。分析了J2、J3摄动以及大气阻力摄动作用下超低轨道卫星偏心率矢量的变化特性;基于能量守恒原理设计了超低轨道高度维持的控制策略;通过仿真算例验证了控制策略的有效性。结果表明:在地球非球形引力摄动、大气阻力摄动和速度脉冲作用下超低轨道平均偏心率的变化是稳定的,所设计的轨道维持方法不仅能够实现超低轨道高度维持,确保平均偏心率矢量收敛至平衡位置,且用于轨道维持的燃料消耗合理,能够满足长时间的超低轨道飞行要求。     

硬质聚氨酯泡沫塑料填充薄壁钢管横向压缩吸能特性分析

为研究硬质聚氨酯泡沫塑料填充薄壁钢管后的吸能特性,对单钢管、钢管嵌套系统及填充硬质聚氨酯泡沫塑料后的钢管进行横向静力压缩试验,并对试验结果进行对比分析。结果表明:硬质聚氨酯泡沫塑料填充管比空钢管的吸能效果有明显提高,其中双钢管嵌套系统填充硬质聚氨酯泡沫塑料后吸能效果提高最明显,三钢管嵌套系统吸收外来的能量值最大。薄壁钢管填充硬质聚氨酯泡沫塑料是一种性能优良的吸能装置,在防护工程中可作为隔爆抗侵彻材料。     

SLOWING DOWN TO KEEP THE LEAD IN MILITARY TECHNOLOGY

We develop a model of military technology competition among states. States can choose to introduce new military technology, mimic rivals’ level of technology, or withdraw from the contest. States can choose to implement any level of technology within their current feasible technologies. We find that states with significant technological leads should sometimes withhold new technologies, only strategically releasing them to trump rivals’ efforts. We develop the model by refining Admiral Jackie Fisher’s roughly articulated concept of ‘plunging’. We then use this refined argument to reanalyze the case of naval rivalries among European powers between the Crimean War and the First World War. Finally, we conclude by discussing the model’s implications for current US military force structure planning.     

EXTRAORDINARY VISITS

North Korea has the bomb but not much of a nuclear arsenal. For fifty years, it pursued the plutonium path to the bomb in parallel with its pursuit of nuclear electricity. My visits to North Korea's Yongbyon nuclear complex provided a window to its plutonium capabilities. After having made six visits to North Korea, Pyongyang surprised me during my seventh visit last November by showing me a small, modern uranium enrichment plant, which I was told was needed for its new indigenous light water reactor program. However, the same capabilities can be used to produce highly enriched uranium bomb fuel. Following a pattern of having made poor risk-management decisions during much of the past twenty years of diplomacy dealing with the North Korean nuclear threat, Washington remains in a standoff with Pyongyang.     

EDITOR'S NOTE

This article offers a survey of risks that might arise for strategic stability (defined as a situation with a low probability of major-power war) with the reduction of US and Russian nuclear arsenals to “low numbers” (defined as 1,000 or fewer nuclear weapons on each side). These risks might include US anti-cities targeting strategies that are harmful to the credibility of extended deterrence; renewed European anxiety about a US-Russian condominium; greater vulnerability to Russian noncompliance with agreed obligations; incentives to adopt destabilizing “launch-on-warning” strategies; a potential stimulus to nuclear proliferation; perceptions of a US disengagement from extended deterrence; increased likelihood of non-nuclear arms competitions and conflicts; and controversial pressures on the UK and French nuclear forces. Observers in North Atlantic Treaty Organization (NATO) states who consider such risks significant have cited four possible measures that might help to contain them: sustained basing of US nonstrategic nuclear weapons in Europe; maintaining a balanced US strategic nuclear force posture; high-readiness means to reconstitute US nuclear forces; and enhanced US and allied non-nuclear military capabilities. These concrete measures might complement the consultations with the NATO allies that the United States would in all likelihood seek with respect to such important adjustments in its deterrence and defense posture.     

CREATING SUNS ON EARTH

Concerns about climate change and energy security have prompted some countries to revive dormant nuclear fission power programs to meet growing energy demands and reduce carbon dioxide emissions. However, this so-called nuclear renaissance based on fission would have major drawbacks in the areas of safety, security, and nonproliferation. Nuclear fusion, however, is portrayed by its proponents as mitigating these drawbacks, and scientists continue to pursue fusion's promise with two large-scale projects: the International Thermonuclear Experimental Reactor (ITER), and the Laser Inertial Fusion Engine (LIFE) reactor. Although supporters often hail fusion as proliferation resistant, the technology could be used to create weapons-usable fissile material. This article explains how fissile material could be created in ITER or LIFE and analyzes other nonproliferation implications of fusion; the authors discuss the various challenges faced by ITER and LIFE.     

INDISPENSABLE INTELLIGENCE AND INEVITABLE FAILURES

Preventing Catastrophe: The Use and Misuse of Intelligence in Efforts to Halt the Proliferation of Weapons of Mass Destruction, by Thomas Graham Jr. and Keith A. Hansen. Stanford University Press, 2009. 300 pages, $35.