本文目录一览：

• 1、plasma是什么意思？
• 2、PLASMA中文是什么
• 3、过浆用英语怎么说
• 4、plasma是什么意思 《西语助手》西汉
• 5、plasma等离子体，这个单词怎么破
• 6、等离子是什么？
• 7、plasma是什么？
• 8、什么是等离子
• 9、plasma可以清洗PCBA吗？会对电子元器件有损伤吗？
• 10、为什么八大处plasma那么贵

plasma是什么意思？

意思：n. 等离子体；血浆读音：英 ['pl?zm?]；美 ['pl?zm?] 用法：与固定名词连用，可以做句子的主语或者宾语。例句：Plasma physics is also pretty neat!等离子体物理也是非常美妙！　 　词语搭配：plasma physics 等离子物理plasma membrane 质膜plasma chemistry 等离子体化学...plasma display panel 等离子显示板,等离子扩展资料：plasma的近义词：blood读音：英 [bl?d]；美 [bl?d] 　 　意思：n. 血；血统；仇恨；vt. 流血用法：blood是不可数名词,没有复数形式，其本意为“血，血液”，也指无脊椎低等动物体中相当于血液的体液；还可引申为“血统,亲属”、“血气,脾气”。表示“流血”一般不说bleed blood，但在美国黑人英语中可说bleed black blood。plasma 是等离子体的意思！！！plasma：等离子体plasma英 ['pl?zm?]美 ['pl?zm?]n. [等离子] 等离子体；血浆；[矿物] 深绿玉髓中文意思是等离子体。plasma英 [?pl?zm?] 美 [?pl?zm?] n. [等离子] 等离子体；血浆；[矿物] 深绿玉髓固定搭配：plasma balance 等离子体平衡 ; 等离子平衡区plasma gas 等离子气 ; [等离子] 等离子气体 ; 等离子体气plasma gun [等离子] 等离子枪 ; [等离子] 等离子体枪 ; [机] 等离子焊枪plasma arc 等离子弧 ; 等离子体电弧 ; 等离子电弧Plasma cells 浆细胞扩展资料近义词：1、plasm中文：血浆，乳浆；等离子体例句：Of woman plasm is different from the parthenogenetic egg? 女子血浆是从不同的孤蛋？2、whey中文：乳清，乳浆例句：I recommend either whey or soy protein shakes. 我推荐乳清或者大豆蛋白奶昔。

PLASMA中文是什么

plasma 英[?pl?zm?] 美[?pl?zm?] n. 血浆; 原生质，细胞质; 乳清; [物] 等离子体; [网络] 等离子; 血浆; 浓绿玉髓; [例句]Objective To explore the characteristics of plasma brain-derived neurotrophic factor ( BDNF) levels in patients with anxiety disorders.目的探讨焦虑障碍患者血浆脑源性神经营养因子（BDNF）水平的特点。求采纳

过浆用英语怎么说

过浆_有道翻译翻译结果：A plasmaplasma_有道词典plasma英 ['pl?zm?]美 ['pl?zm?]n. [等离子] 等离子体；血浆；[矿物] 深绿玉髓更多释义>>[网络短语]PLASMA 等离子,等离子体,等离子体Plasma protein 血浆蛋白,血浆蛋白质,血浆蛋白粉plasma exchange 血浆置换,浆置换,血浆交换

plasma是什么意思 《西语助手》西汉

plasma音标：['plazma]词义：1.【生】原生质.2.【生理】（血液或淋巴的）浆3.【矿】深绿玉髓.4.【理】等离子体,等离子区

plasma等离子体，这个单词怎么破

plasma ['pl?zm?] n.等离子体；血浆；[矿物] 深绿玉髓。希腊词根plas-表to spread，与日耳曼词源的flat同源，因为向四处扩散后会形成一个平面，比如熟词plastic ['pl?st?k] adj.塑料的；造型的；可塑的，n.塑料，是因为塑料可塑成平的。而-ma后缀表行为结果和产物，所以plasma是something molded。"plasma"一词最早在生物学名词原生质（proto plasma）中出现。1839年，捷克生物学家浦基尼（Purkynie）最先将“原生质”引入科学词汇。它表示一种在其内部散布许多粒子的胶状物质，是组成细胞体的一部分，也称“血浆”。

等离子是什么？

等离子状态使指物质原子内的电子在高温下脱离原子核的吸引，使物质呈为正负带电粒子状态存在。我们知道，把冰加热到一定程度，它就会变成液态的水，如果继续升高温度，液态的水就会变成气态，如果继续升高温度到几千度以上，气体的原子就会抛掉身上的电子，发生气体的电离化现象，物理学家把电离化的气体就叫做等离子态。 在茫茫无际的宇宙空间里，等离子态是一种普遍存在的状态。宇宙中大部分发光的星球内部温度和压力都很高，这些星球内部的物质差不多都处于等离子态。只有那些昏暗的行星和分散的星际物质里才可以找到固态、液态和气态的物质。 就在我们周围，也经常看到等离子态的物质。在日光灯和霓虹灯的灯管里，在眩目的白炽电弧里，都能找到它的踪迹。另外，在地球周围的电离层里，在美丽的极光、大气中的闪光放电和流星的尾巴里，也能找到奇妙的等离子态。所谓等离子彩电PDP（P la sm a D isp lay Pan e l）是在两张薄玻璃板之间充填混合气体，施加电压使之产生离子气体，然后使等离子气体放电，与基板中的荧光体发生反应，产生彩色影像。等离子彩电又称“壁挂式电视”，不受磁力和磁场影响，具有机身纤薄、重量轻、屏幕大、色彩鲜艳、画面清晰、亮度高、失真度小、节省空间等优点。等离子体 （ 等离子态 ， 电浆 ， 英文 ： Plasma ）是一种 电离 的气体，由于存在电离出来的 自由电子 和带电 离子 ，等离子体具有很高的 电导率 ，与 电磁场 存在极强的 耦合 作用。等离子态在 宇宙 中广泛存在，常被看作物质的第四态（有人也称之为“ 超气态 ”）。等离子体由 克鲁克斯 在1879年发现，“Plasma”这个词，由 朗廖尔 在1928年最早采用。等离子体又被称为电浆 是被电离后产生的正负离子组合的离子化气体状物质 那如何直观的理解等离子体呢等离子体(plasma)又叫做电浆，是由部分电子被剥夺后的原子及原子团被电离后产生的正负离子组成的离子化气体状物质，尺度大于德拜长度的宏观电中性电离气体。等离子体是什么？等离子体 （ 等离子态 ， 电浆 ， 英文 ： Plasma ）是一种 电离 的气体，由于存在电离出来的 自由电子 和带电 离子 ，等离子体具有很高的 电导率 ，与 电磁场 存在极强的 耦合 作用。等离子态在 宇宙 中广泛存在，常被看作物质的第四态（有人也称之为“ 超气态 ”）。等离子体由 克鲁克斯 在1879年发现，“Plasma”这个词，由 朗廖尔 在1928年最早采用。 常见的等离子体 等离子体是存在最广泛的一种 物态 ，目前观测到的宇宙物质中，99%都是等离子体。 人造的等离子体 荧光灯 ， 霓虹灯 灯管中的电离气体 核聚变 实验中的高温电离气体 电焊 时产生的高温 电弧 地球上的等离子体 火焰 （上部的高温部分） 闪电 大气层 中的 电离层 极光 宇宙空间中的等离子体 恒星 太阳风 行星际物质 恒星际物质 星云 其它等离子体 等离子体的性质 等离子态常被称为“超气态”，它和气体有很多相似之处，比如：没有确定 形状 和 体积 ，具有 流动性 ，但等离子也有很多独特的性质。 电离 等离子体和普通气体的最大区别是它是一种电离气体。由于存在带负电的自由电子和带正电的离子，有很高的电导率，和电磁场的 耦合 作用也极强：带电粒子可以同 电场 耦合，带电粒子流可以和 磁场 耦合。描述等离子体要用到 电动力学 ，并因此发展起来一门叫做 磁流体动力学 的理论。 组成粒子 和一般气体不同的是，等离子体包含两到三种不同组成粒子：自由电子，带正电的离子和未电离的 原子 。这使得我们针对不同的组分定义不同的 温度 ：电子温度和离子温度。轻度电离的等离子体，离子温度一般远低于电子温度，称之为“低温等离子体”。高度电离的等离子体，离子温度和电子温度都很高，称为“高温等离子体”。 相比于一般气体，等离子体组成粒子间的相互作用也大很多。 速率分布 一般气体的速率分布满足 麦克斯韦分布 ，但等离子体由于与电场的耦合，可能偏离麦克斯韦分布。 --------------------------------------------------------------------------------大众天文网 http://allastronomy.lamost.org

plasma是什么？

plasma：等离子体

什么是等离子

PDP（Plasma Display Panel，等离子显示）是一种利用气体放电的显示技术，其工作原理与日光灯很相似。它采用了等离子管作为发光元件，屏幕上每一个等离子管对应一个像素，屏幕以玻璃作为基板，基板间隔一定距离，四周经气密性封接形成一个个放电空间。放电空间内充入氖、氙等混合惰性气体作为工作媒质。在两块玻璃基板的内侧面上涂有金属氧化物导电薄膜作激励电极。 当向电极上加入电压，放电空间内的混合气体便发生等离子体放电现象。气体等离子体放电产生紫外线，紫外线激发荧光屏，荧光屏发射出可见光，显现出图像。当使用涂有三原色（也称三基色）荧光粉的荧光屏时，紫外线激发荧光屏，荧光屏发出的光则呈红、绿、蓝三原色。当每一原色单元实现256级灰度后再进行混色，便实现彩色显示。等离子体显示器技术按其工作方式可分为电极与气体直接接触的直流型PDP和电极上覆盖介质层的交流型PDP两大类。目前研究开发的彩色PDP的类型主要有三种：单基板式（又称表面放电式）交流PDP、双基板式（又称对向放电式）交流PDP和脉冲存储直流PDP。 PDP最先进显示技术之一。它固有的优势决定了其生命力。 从技术原理上看，由于PDP屏幕中发光的等离子管在平面中均匀分布，这样显示图像的中心和边缘完全一致，不会出现扭曲现象，实现了真正意义上的纯平面。由于其显示过程中没有电子束运动，不需要借助于电磁场，因此外界的电磁场也不会对其产生干扰，具有较好的环境适应性。 PDP是一种自发光显示技术，不需要背景光源，因此没有LCD显示器的视角和亮度均匀性问题，而且实现了较高的亮度和对比度。而三基色共用同一个等离子管的设计也使其避免了聚焦和汇聚问题，可以实现非常清晰的图像。与CRT和LCD显示技术相比，PDP的屏幕越大，图像的景深和保真度越高。 除了亮度、对比度和可视角度优势外，PDP技术也避免了LCD技术中的响应时间问题，而这些特点正是动态视频显示中至关重要的因素。因此从目前的技术水平看，PDP显示技术在动态视频显示领域的优势更加明显，更加适合作为电视机或家庭影院显示终端使用。 PDP显示器无扫描线扫描，因此图像清晰稳定无闪烁，不会导致眼睛疲劳。PDP也无X射线辐射。由于这两个特点，PDP堪称真正意义上的绿色环保显示产品，是替代传统CRT彩电的理想产品。等离子体又被称为电浆 是被电离后产生的正负离子组合的离子化气体状物质 那如何直观的理解等离子体呢等离子体是什么？等离子体(plasma)又叫做电浆，是由部分电子被剥夺后的原子及原子团被电离后产生的正负离子组成的离子化气体状物质，尺度大于德拜长度的宏观电中性电离气体，其运动主要受电磁力支配，并表现出显著的集体行为。它广泛存在于宇宙中，常被视为是除去固、液、气外，物质存在的第四态。等离子体是一种很好的导电体，利用经过巧妙设计的磁场可以捕捉、移动和加速等离子体。等离子体物理的发展为材料、能源、信息、环境空间、空间物理、地球物理等科学的进一步发展提供了新的技术和工艺。扩展资料：等离子体主要用于以下3方面。1、等离子体冶炼：用于冶炼用普通方法难于冶炼的材料，例如高熔点的锆 (Zr)、钛(Ti)、钽(Ta)、铌(Nb)、钒(V)、钨(W)等金属；还用于简化工艺过程，例如直接从ZrCl4、MoS2、Ta2O5和TiCl4中分别获得Zr、Mo、Ta和Ti。用等离子体熔化快速固化法可开发硬的高熔点粉末，如碳化钨-钴、Mo-Co、Mo-Ti-Zr-C等粉末。 等离子体冶炼的优点是产品成分及微结构的一致性好，可免除容器材料的污染。2、等离子体喷涂：许多设备的部件应能耐磨、耐腐蚀、抗高温，为此需要在其表面喷涂一层具有特殊性能的材料。用等离子体沉积快速固化法可将特种材料粉末喷入热等离子体中熔化，并喷涂到基体（部件）上，使之迅速冷却、固化，形成接近网状结构的表层，这可大大提高喷涂质量。3、等离子体焊接：可用以焊接钢、合金钢；铝、铜、钛等及其合金。特点是焊缝平整，可以再加工,没有氧化物杂质,焊接速度快。用于切割钢、铝及其合金，切割厚度大。参考资料：百度百科—等离子体/等离子体维基百科，自由的百科全书Jump to: navigation, search等离子灯放大等离子灯等离子体（等离子态，电浆，英文：Plasma）是一种电离的气体，由于存在电离出来的自由电子和带电离子，等离子体具有很高的电导率，与电磁场存在极强的耦合作用。等离子态在宇宙中广泛存在，常被看作物质的第四态（有人也称之为“超气态”）。等离子体由克鲁克斯在1879年发现，“Plasma”这个词，由朗廖尔在1928年最早采用。目录[隐藏] * * o 2.1 电离 o o 2.3 速率分布 * 3 参见[编辑]常见的等离子体等离子体是存在最广泛的一种物态，目前观测到的宇宙物质中，99%都是等离子体。 * 人造的等离子体 o 荧光灯，霓虹灯灯管中的电离气体 o 核聚变实验中的高温电离气体 o 电焊时产生的高温电弧 * 地球上的等离子体 o 火焰（上部的高温部分） o 闪电 o 大气层中的电离层 o 极光 * 宇宙空间中的等离子体 o 恒星 o 太阳风 o 行星际物质 o 恒星际物质 o 星云 * 其它等离子体[编辑]等离子体的性质等离子态常被称为“超气态”，它和气体有很多相似之处，比如：没有确定形状和体积，具有流动性，但等离子也有很多独特的性质。[编辑]电离等离子体和普通气体的最大区别是它是一种电离气体。由于存在带负电的自由电子和带正电的离子，有很高的电导率，和电磁场的耦合作用也极强：带电粒子可以同电场耦合，带电粒子流可以和磁场耦合。描述等离子体要用到电动力学，并因此发展起来一门叫做磁流体动力学的理论。[编辑]组成粒子和一般气体不同的是，等离子体包含两到三种不同组成粒子：自由电子，带正电的离子和未电离的原子。这使得我们针对不同的组分定义不同的温度：电子温度和离子温度。轻度电离的等离子体，离子温度一般远低于电子温度，称之为“低温等离子体”。高度电离的等离子体，离子温度和电子温度都很高，称为“高温等离子体”。相比于一般气体，等离子体组成粒子间的相互作用也大很多。[编辑]速率分布一般气体的速率分布满足麦克斯韦分布，但等离子体由于与电场的耦合，可能偏离麦克斯韦分布。[编辑]参见 * 等离子体物理学取自"http://zh.wikipedia.org/wiki/%E7%AD%89%E7%A6%BB%E5%AD%90%E4%BD%93"Category: 等离子体物理学Plasma (physics)From Wikipedia, the free encyclopedia.Jump to: navigation, search This article is about plasma in the sense of an ionized gas. For other uses of the term, such as blood plasma, see plasma (disambiguation).A Plasma lamp, illustrating some of the more complex phenomena of a plasma, including filamentationEnlargeA Plasma lamp, illustrating some of the more complex phenomena of a plasma, including filamentationIn physics and chemistry, a plasma is an ionized gas, and is usually considered to be a distinct phase of matter. "Ionized" in this case means that at least one electron has been removed from a significant fraction of the molecules. The free electric charges make the plasma electrically conductive so that it couples strongly to electromagnetic fields. This fourth state of matter was first identified by Sir William Crookes in 1879 and dubbed "plasma" by Irving Langmuir in 1928, because it reminded him of a blood plasma Ref.Contents[hide] * 1 Common plasmas * 2 Characteristics o 2.1 Plasma scaling o 2.2 Temperatures o 2.3 Densities o 2.4 Potentials * 3 In contrast to the gas phase * 4 Complex plasma phenomena * 5 Ultracold Plasmas * 6 Mathematical descriptions o 6.1 Fluid o 6.2 Kinetic o 6.3 Particle-in-cell * 7 Fundamental plasma parameters o 7.1 Frequencies o 7.2 Lengths o 7.3 Velocities o 7.4 Dimensionless o 7.5 Miscellaneous * 8 Fields of active research * 9 See also * 10 External links[edit]Common plasmasA solar coronal mass ejection blasts plasma throughout the Solar System. http://antwrp.gsfc.nasa.gov/apod/ap020516.html Ref & CreditEnlargeA solar coronal mass ejection blasts plasma throughout the Solar System. http://antwrp.gsfc.nasa.gov/apod/ap020516.html Ref & CreditPlasmas are the most common phase of matter. The entire visible universe outside the Solar System is plasma, since all we can see are stars. Since the space between the stars is filled with a plasma, although a very sparse one (see interstellar- and intergalactic medium), essentially the entire volume of the universe is plasma. In the Solar System, the planet Jupiter accounts for most of the non-plasma, only about 0.1% of the mass and 10-15 of the volume within the orbit of Pluto. Alfvén also noted that due to their electric charge, very small grains also behave as ions and form part of a plasma (see dusty plasmas).Commonly encountered forms of plasma include: * Artificially produced o Inside fluorescent lamps (low energy lighting), neon signs o Rocket exhaust o The area in front of a spacecraft's heat shield during reentry into the atmosphere o Fusion energy research o The electric arc in an arc lamp or an arc welder o Plasma ball (sometimes called a plasma sphere or plasma globe) * Earth plasmas o Flames (ie. fire) o Lightning o The ionosphere o The polar aurorae * Space and astrophysical o The Sun and other stars (which are plasmas heated by nuclear fusion) o The solar wind o The Interplanetary medium (the space between the planets) o The Interstellar medium (the space between star systems) o The Intergalactic medium (the space between galaxies) o The Io-Jupiter flux-tube o Accretion disks o Interstellar nebulae[edit]CharacteristicsThe term plasma is generally reserved for a system of charged particles large enough to behave as one. Even a partially ionized gas in which as little as 1% of the particles are ionized can have the characteristics of a plasma (i.e. respond to magnetic fields and be highly electrically conductive).In technical terms, the typical characteristics of a plasma are: 1. Debye screening lengths that are short compared to the physical size of the plasma. 2. Large number of particles within a sphere with a radius of the Debye length. 3. Mean time between collisions usually is long when compared to the period of plasma oscillations.[edit]Plasma scalingPlasmas and their characteristics exist over a wide range of scales (ie. they are scaleable over many orders of magnitude). The following chart deals only with conventional atomic plasmas and not other exotic phenomena, such as, quark gluon plasmas: Typical plasma scaling ranges: orders of magnitude (OOM)Characteristic Terrestrial plasmas Cosmic plasmasSizein metres (m) 10-6 m (lab plasmas) to:102 m (lightning) (~8 OOM) 10-6 m (spacecraft sheath) to1025 m (intergalactic nebula) (~31 OOM)Lifetimein seconds (s) 10-12 s (laser-produced plasma) to:107 s (fluorescent lights) (~19 OOM) 101 s (solar flares) to:1017 s (intergalactic plasma) (~17 OOM)Densityin particles percubic metre 107 to:1021 (inertial confinement plasma) 1030 (stellar core) to:100 (i.e., 1) (intergalactic medium)Temperaturein kelvins (K) ~0 K (Crystalline non-neutral plasma[2]) to:108 K (magnetic fusion plasma) 102 K (aurora) to:107 K (Solar core)Magnetic fieldsin teslas (T) 10-4 T (Lab plasma) to:103 T (pulsed-power plasma) 10-12 T (intergalactic medium) to:107 T (Solar core)[edit]TemperaturesThe central electrode of a plasma lamp, showing a glowing blue plasma streaming upwards. The colors are a result of the radiative recombination of electrons and ions and the relaxation of electrons in excited states back to lower energy states. These processes emit light in a spectrum characteristic of the gas being excited.EnlargeThe central electrode of a plasma lamp, showing a glowing blue plasma streaming upwards. The colors are a result of the radiative recombination of electrons and ions and the relaxation of electrons in excited states back to lower energy states. These processes emit light in a spectrum characteristic of the gas being excited.The defining characteristic of a plasma is ionization. Although ionization can be caused by UV radiation, energetic particles, or strong electric fields, (processes that tend to result in a non-Maxwellian electron distribution function), it is more commonly caused by heating the electrons in such a way that they are close to thermal equilibrium so the electron temperature is relatively well-defined. Because the large mass of the ions relative to the electrons hinders energy transfer, it is possible for the ion temperature to be very different from (usually lower than) the electron temperature.The degree of ionization is determined by the electron temperature relative to the ionization energy (and more weakly by the density) in accordance with the Saha equation. If only a small fraction of the gas molecules are ionized (for example 1%), then the plasma is said to be a cold plasma, even though the electron temperature is typically several thousand degrees. The ion temperature in a cold plasma is often near the ambient temperature. Because the plasmas utilized in plasma technology are typically cold, they are sometimes called technological plasmas. They are often created by using a very high electric field to accelerate electrons, which then ionize the atoms. The electric field is either capacitively or inductively coupled into the gas by means of a plasma source, e.g. microwaves. Common applications of cold plasmas include plasma-enhanced chemical vapor deposition, plasma ion doping, and reactive ion etching.A hot plasma, on the other hand, is nearly fully ionized. This is what would commonly be known as the "fourth-state of matter". The Sun is an example of a hot plasma. The electrons and ions are more likely to have equal temperatures in a hot plasma, but there can still be significant differences.[edit]DensitiesNext to the temperature, which is of fundamental importance for the very existence of a plasma, the most important property is the density. The word "plasma density" by itself usually refers to the electron density, that is, the number of free electrons per unit volume. The ion density is related to this by the average charge state \langle Z\rangle of the ions through n_e=\langle Z\rangle n_i. (See quasineutrality below.) The third important quantity is the density of neutrals n0. In a hot plasma this is small, but may still determine important physics. The degree of ionization is ni / (n0 + ni).[edit]PotentialsLightning is an example of plasma present at Earth's surface. Typically, lightning discharges 30 thousand amps, at up to 100 million volts, and emits light, radio waves, x-rays and even gamma rays [1]. Plasma temperatures in lightning can approach 28,000 kelvins and electron densities may exceed 1024/m3.EnlargeLightning is an example of plasma present at Earth's surface. Typically, lightning discharges 30 thousand amps, at up to 100 million volts, and emits light, radio waves, x-rays and even gamma rays [1]. Plasma temperatures in lightning can approach 28,000 kelvins and electron densities may exceed 1024/m3.Since plasmas are very good conductors, electric potentials play an important role. The potential as it exists on average in the space between charged particles, independent of the question of how it can be measured, is called the plasma potential or the space potential. If an electrode is inserted into a plasma, its potential will generally lie considerably below the plasma potential due to the development of a Debye sheath. Due to the good electrical conductivity, the electric fields in plasmas tend to be very small, although where double layers are formed, the potential drop can be large enough to accelerate ions to relativistic velocities and produce synchrotron radiation such as x-rays and gamma rays. This results in the important concept of quasineutrality, which says that, on the one hand, it is a very good approximation to assume that the density of negative charges is equal to the density of positive charges (n_e=\langle Z\rangle n_i), but that, on the other hand, electric fields can be assumed to exist as needed for the physics at hand.The magnitude of the potentials and electric fields must be determined by means other than simply finding the net charge density. A common example is to assume that the electrons satisfy the Boltzmann relation, n_e \propto e^{e\Phi/k_BT_e}. Differentiating this relation provides a means to calculate the electric field from the density: \vec{E} = (k_BT_e/e)(\nabla n_e/n_e).It is, of course, possible to produce a plasma that is not quasineutral. An electron beam, for example, has only negative charges. The density of a non-neutral plasma must generally be very low, or it must be very small, otherwise it will be dissipated by the repulsive electrostatic force.In astrophysical plasmas, Debye screening prevents electric fields from directly affecting the plasma over large distances (ie. greater than the Debye length). But the existence of charged particles causes the plasma to generate and be affected by magnetic fields. This can and does cause extremely complex behavior, such as the generation of plasma double layers, an object that separates charge over a few tens of Debye lengths. The dynamics of plasmas interacting with external and self-generated magnetic fields are studied in the academic discipline of magnetohydrodynamics.[edit]In contrast to the gas phasePlasma is often called the fourth state of matter. It is distinct from the three lower-energy phases of matter; solid, liquid, and gas, although it is closely related to the gas phase in that it also has no definite form or volume. There is still some disagreement as to whether a plasma is a distinct state of matter or simply a type of gas. Most physicists consider a plasma to be more than a gas because of a number of distinct properties including the following:Property Gas PlasmaElectrical Conductivity Very low Very high 1. For many purposes the electric field in a plasma may be treated as zero, although when current flows the voltage drop, though small, is finite, and density gradients are usually associated with an electric field according to the Boltzmann relation. 2. The possibility of currents couples the plasma strongly to magnetic fields, which are responsible for a large variety of structures such as filaments, sheets, and jets. 3. Collective phenomena are common because the electric and magnetic forces are both long-range and potentially many orders of magnitude stronger than gravitational forces.Independently acting species One Two or threeElectrons, ions, and neutrals can be distinguished by the sign of their charge so that they behave independently in many circumstances, having different velocities or even different temperatures, leading to new types of waves and instabilities, among other thingsVelocity distribution Maxwellian May be non-MaxwellianWhereas collisional interactions always lead to a Maxwellian velocity distribution, electric fields influence the particle velocities differently. The velocity dependence of the Coulomb collision cross section can amplify these differences, resulting in phenomena like two-temperature distributions and run-away electrons.Interactions BinaryTwo-particle collisions are the rule, three-body collisions extremely rare. CollectiveEach particle interacts simultaneously with many others. These collective interactions are about ten times more important than binary collisions.[edit]Complex plasma phenomenaTycho's Supernova remnant, a huge ball of expanding plasma. Langmuir coined the name plasma because of its similarity to blood plasma, and Hannes Alfvén noted its cellular nature. Note also the filamentary blue outer shell of X-ray emitting high-speed electronsEnlargeTycho's Supernova remnant, a huge ball of expanding plasma. Langmuir coined the name plasma because of its similarity to blood plasma, and Hannes Alfvén noted its cellular nature. Note also the filamentary blue outer shell of X-ray emitting high-speed electronsPlasma may exhibit complex behaviour. And just as plasma properties scale over many orders of magnitude (see table above), so do these complex features. Many of these features were first studied in the laboratory, and in more recent years, have been applied to, and recognised throughout the universe. Some of these features include: * Filamentation, the striations or "stringy things" seen in a "plasma ball", the aurora, lightning, and nebulae. They are caused by larger current densities, and are also called magnetic ropes or plasma cables. * Double layers, localised charge separation regions that have a large potential difference across the layer, and a vanishing electric field on either side. Double layers are found between adjacent plasmas regions with different physical characteristics, and can accelerate ions and produce synchrotron radiation (such as x-rays and gamma rays). * Birkeland currents, a magnetic-field-aligned electric current, first observed in the Earth's aurora, and also found in plasma filaments. * Circuits. Birkeland currents imply electric circuits, that follow Kirchhoff's circuit laws. Circuits have a resistance and inductance, and the behaviour of the plasma depends on the entire circuit. Such circuits also store inductive energy, and should the circuit be disrupted, for example, by a plasma instability, the inductive energy will be released in the plasma. * Cellular structure. Plasma double layers may separate regions with different properties such as magnetization, density, and temperature, resulting in cell-like regions. Examples include the magnetosphere, heliosphere, and heliospheric current sheet. * Critical ionization velocity in which the relative velocity between an ionized plasma and a neutral gas, may cause further ionization of the gas, resulting in a greater influence of electomagnetic forces.[edit]Ultracold PlasmasIt is also possible to create ultracold plasmas, by using lasers to trap and cool neutral atoms to temperatures of 1 mK or lower. Another laser then ionizes the atoms by giving each of the outermost electrons just enough energy to escape the electrical attraction of its parent ion.The key point about ultracold plasmas is that by manipulating the atoms with lasers, the kinetic energy of the liberated electrons can be controlled. Using standard pulsed lasers, the electron energy can be made to correspond to a temperature of as low as 0.1 K - a limit set by the frequency bandwidth of the laser pulse. The ions, however, retain the millikelvin temperatures of the neutral atoms. This type of non-equilibrium ultracold plasma evolves rapidly, and many fundamental questions about its behaviour remain unanswered. Experiments conducted so far have revealed surprising dynamics and recombination behaviour that are pushing the limits of our knowledge of plasma physics.[edit]Mathematical descriptionsPlasmas may be usefully described with various levels of detail. However the plasma itself is described, if electric or magnetic fields are present, then Maxwell's equations will be needed to describe them. The coupling of the description of a conductive fluid to electromagnetic fields is known generally as magnetohydrodynamics, or simply MHD.[edit]FluidThe simplest possibility is to treat the plasma as a single fluid governed by the Navier Stokes Equations. A more general description is the two-fluid picture, where the ions and electrons are considered to be distinct.[edit]KineticFor some cases the fluid description is not sufficient. Kinetic models inc

plasma可以清洗PCBA吗？会对电子元器件有损伤吗？

可以，不会的。Plasma清洗是指在under-fill前对我们的PCBA进行清洁,其目的清除产品表面的污染物，降低表面张力，使Under-fill胶水充分填满需要点胶的元件。是的，等离子体(plasma)清洗可以应用于PCBA(Printed Circuit Board Assembly)的清洗过程。它是一种非接触式的清洗方法，可以有效去除PCBA表面的有机和无机污染物。等离子体清洗有以下优势：1. 高效清洗：等离子体清洗能够在短时间内有效清除表面污染物，包括有机物、油污、粉尘等。2. 非接触式：等离子体清洗是一种非接触式的清洗方法，不会对PCBA上的电子元器件进行机械性损伤。3. 无残留物：等离子体清洗可以将有机物完全分解，不会在PCBA表面留下任何残留物，避免了溶剂残留导致的后续问题。然而，需要提醒的是，虽然等离子体清洗是一种较为安全且高效的清洗方法，但在实际操作中仍需遵循以下注意事项：1. 控制条件：需要掌握适当的等离子体清洗参数，如功率、气体组成、处理时间等，以避免过度清洗造成损伤。2. 部分敏感元器件的考虑：对于某些特定的敏感电子元器件(如MEMS、压力传感器、光学元件等)，需要评估等离子体清洗对其的影响，并谨慎进行操作。3. 选择适当的等离子体清洗设备：根据需求选择适合的清洗设备，确保设备的稳定性和可靠性。

为什么八大处plasma那么贵

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