VOA慢速英语--美国海军取消研制电磁轨道炮武器

The U.S. Navy is halting development of a high-tech¹ weapon designed to fire projectiles³ at up to seven times the speed of sound.

The Navy spent more than 10 years developing the weapon, called an electromagnetic railgun. The cannon⁴-like railgun uses electricity instead of chemical substances to fire projectiles.

A report released earlier this year by the Congressional Research Service stated that the Navy had been developing the railgun as a firing weapon to support U.S. Marines operations. The report said the development also centered on possible use of the railgun as a missile defense⁵ system.

The move to cancel railgun development comes as the U.S. Department of Defense turns its attention to the development of hypersonic missiles, The Associated Press reports.

Hypersonic is a term that relates to speeds of more than five times the speed of sound, also known as Mach 5. In addition to flying at extremely high speeds, hypersonic weapons are designed to move in ways that make them difficult to find and destroy in flight.

The U.S. military has been putting money into the development of hypersonic weapons in recent years in an effort to keep up with hypersonic military programs in China and Russia.

Matthew Caris is a defense expert with the private advisory⁶ company Avascent Group. He told the AP that "the railgun is, for the moment, dead."

The halt in railgun development, Caris said, suggests that the Navy saw difficulties in implementing⁸ the technology. In addition, the Navy likely recognized that hypersonic missiles have higher performing abilities than the railgun, he added.

Lieutenant⁹ Courtney Callaghan is a Navy spokesperson. She told the AP that the Navy's decision will free up resources for hypersonic missiles, as well as lasers and other electronic warfare¹⁰ systems.

The Navy spent about $500 million on research and development of the railgun, said Bryan Clark, a defense expert at the Hudson Institute.

The railgun held the possibility of providing an effective weapon at a much lower cost than smart bombs and missiles. Using electricity, a railgun can fire a projectile² at six or seven times the speed of sound, creating enough energy to destroy targets.

But Clark said the program experienced a number of problems, including the limited range of the railgun in testing. In addition, its usefulness for missile defense was also limited by range and rate of fire, Clark added.

Another big question was whether the gun could stay together during continuous firing, said defense analyst¹¹ Norman Friedman.

A normal gun can be fired about 600 times before the barrel has to be refurbished. But the barrel on tested railguns, Clark said, had to be replaced after about 12 to 24 shots were fired.

A few years ago, the Navy was talking about putting the gun on the future USS Lyndon B. Johnson, the last of three stealthy destroyers. But now, the Navy is developing what it calls a "hypervelocity projectile," which is designed to be fired from existing gun systems.

Words in This Story

projectile – n. an object that is thrown or shot forward with force

cannon – n. a large, powerful gun, usually attached to two or four wheels, that was used in the past to fire heavy balls

implement⁷ – v. to start using a plan or system

barrel – n. the long part of a gun that is shaped like a tube

refurbish – v. to improve or restore something to working order

stealthy – adj. quiet and careful in order not to be seen or heard

1 high-tech   

adj.高科技的

参考例句：

• The economy is in the upswing which makes high-tech services in more demand too.经济在蓬勃发展，这就使对高科技服务的需求量也在加大。
• The quest of a cure for disease with high-tech has never ceased. 人们希望运用高科技治疗疾病的追求从未停止过。

2 projectile   

n.投射物，发射体；adj.向前开进的；推进的；抛掷的

参考例句：

• The vertical and horizontal motions of a projectile can be treated independently.抛射体的竖直方向和水平方向的运动能够分开来处理。
• Have you altered the plans of the projectile as the telegram suggests?你已经按照电报的要求修改炮弹图样了吗?

3 projectiles   

n.抛射体( projectile的名词复数 )；（炮弹、子弹等）射弹，（火箭等）自动推进的武器

参考例句：

• These differences are connected with the strong absorption of the composite projectiles. 这些差别与复杂的入射粒子的强烈吸收有关。 来自辞典例句
• Projectiles became more important because cannons could now fire balls over hundreds or yards. 抛射体变得更加重要，因为人们已能用大炮把炮弹射到几百码的距离之外。 来自辞典例句

4 cannon   

n.大炮，火炮；飞机上的机关炮

参考例句：

• The soldiers fired the cannon.士兵们开炮。
• The cannon thundered in the hills.大炮在山间轰鸣。

5 defense   

n.防御，保卫；[pl.]防务工事；辩护，答辩

参考例句：

• The accused has the right to defense.被告人有权获得辩护。
• The war has impacted the area with military and defense workers.战争使那个地区挤满了军队和防御工程人员。

6 advisory   

adj.劝告的，忠告的，顾问的，提供咨询

参考例句：

• I have worked in an advisory capacity with many hospitals.我曾在多家医院做过顾问工作。
• He was appointed to the advisory committee last month.他上个月获任命为顾问委员会委员。

7 implement   

n.(pl.)工具，器具；vt.实行，实施，执行

参考例句：

• Don't undertake a project unless you can implement it.不要承担一项计划，除非你能完成这项计划。
• The best implement for digging a garden is a spade.在花园里挖土的最好工具是铁锹。

8 implementing   

v.实现( implement的现在分词 )；执行；贯彻；使生效

参考例句：

• -- Implementing a comprehensive drug control strategy. ――实行综合治理的禁毒战略。 来自汉英非文学 - 白皮书
• He was in no hurry about implementing his unshakable principle. 他并不急于实行他那不可动摇的原则。 来自辞典例句

9 lieutenant   

n.陆军中尉，海军上尉；代理官员，副职官员

参考例句：

• He was promoted to be a lieutenant in the army.他被提升为陆军中尉。
• He prevailed on the lieutenant to send in a short note.他说动那个副官，递上了一张简短的便条进去。

10 warfare   

n.战争(状态)；斗争；冲突

参考例句：

• He addressed the audience on the subject of atomic warfare.他向听众演讲有关原子战争的问题。
• Their struggle consists mainly in peasant guerrilla warfare.他们的斗争主要是农民游击战。

11 analyst   

n.分析家，化验员；心理分析学家

参考例句：

• What can you contribute to the position of a market analyst?你有什么技能可有助于市场分析员的职务？
• The analyst is required to interpolate values between standards.分析人员需要在这些标准中插入一些值。