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是(shi)一(yi)(yi)(yi)种(zhong)用(yong)来(lai)检(jian)(jian)漏(lou)(lou)(lou)(lou)(lou)的(de)(de)(de)(de)对比(bi)(bi)仪(yi)(yi)器(qi)。它是(shi)一(yi)(yi)(yi)种(zhong)质谱分析仪(yi)(yi),检(jian)(jian)漏(lou)(lou)(lou)(lou)(lou)时(shi)(shi)以(yi)氦(hai)气作(zuo)(zuo)(zuo)为示(shi)踪(zong)介质,当(dang)氦(hai)气与(yu)其它气体一(yi)(yi)(yi)同进(jin)入(ru)仪(yi)(yi)器(qi)内部时(shi)(shi)即被(bei)电(dian)离,并(bing)在(zai)(zai)(zai)质谱室的(de)(de)(de)(de)电(dian)磁场中(zhong)(zhong)作(zuo)(zuo)(zuo)圆周运动;由(you)于(yu)各(ge)种(zhong)气体的(de)(de)(de)(de)质量不一(yi)(yi)(yi)样(yang)(yang),因(yin)而形成许多(duo)束圆半(ban)径不一(yi)(yi)(yi)样(yang)(yang)的(de)(de)(de)(de)电(dian)子流,其中(zhong)(zhong)只有氦(hai)子流可被(bei)接收,经放(fang)大(da)后在(zai)(zai)(zai)仪(yi)(yi)器(qi)的(de)(de)(de)(de)输出(chu)表上显(xian)示(shi)一(yi)(yi)(yi)个电(dian)量,进(jin)入(ru)的(de)(de)(de)(de)氦(hai)气越(yue)(yue)多(duo),显(xian)示(shi)的(de)(de)(de)(de)电(dian)量越(yue)(yue)大(da)。工(gong)(gong)件检(jian)(jian)漏(lou)(lou)(lou)(lou)(lou)时(shi)(shi),可以(yi)用(yong)不同的(de)(de)(de)(de)方式将(jiang)(jiang)工(gong)(gong)件与(yu)检(jian)(jian)漏(lou)(lou)(lou)(lou)(lou)仪(yi)(yi)连(lian)接在(zai)(zai)(zai)一(yi)(yi)(yi)起,使氦(hai)气通过(guo)工(gong)(gong)件漏(lou)(lou)(lou)(lou)(lou)孔(kong)并(bing)进(jin)入(ru)检(jian)(jian)漏(lou)(lou)(lou)(lou)(lou)仪(yi)(yi)。检(jian)(jian)漏(lou)(lou)(lou)(lou)(lou)仪(yi)(yi)上只有电(dian)量显(xian)示(shi),但相应(ying)的(de)(de)(de)(de)电(dian)量相当(dang)于(yu)多(duo)大(da)的(de)(de)(de)(de)漏(lou)(lou)(lou)(lou)(lou)率还不知道。为此,可以(yi)用(yong)一(yi)(yi)(yi)支已知漏(lou)(lou)(lou)(lou)(lou)率的(de)(de)(de)(de)漏(lou)(lou)(lou)(lou)(lou)孔(kong)(习惯上称(cheng)作(zuo)(zuo)(zuo)标准(zhun)(zhun)漏(lou)(lou)(lou)(lou)(lou)孔(kong)) ,将(jiang)(jiang)它与(yu)检(jian)(jian)漏(lou)(lou)(lou)(lou)(lou)仪(yi)(yi)连(lian)接在(zai)(zai)(zai)一(yi)(yi)(yi)起,使通过(guo)标准(zhun)(zhun)漏(lou)(lou)(lou)(lou)(lou)孔(kong)的(de)(de)(de)(de)氦(hai)气也(ye)在(zai)(zai)(zai)检(jian)(jian)漏(lou)(lou)(lou)(lou)(lou)仪(yi)(yi)上有一(yi)(yi)(yi)电(dian)量显(xian)示(shi)。以(yi)标准(zhun)(zhun)漏(lou)(lou)(lou)(lou)(lou)孔(kong)显(xian)示(shi)的(de)(de)(de)(de)电(dian)量作(zuo)(zuo)(zuo)为基(ji)(ji)准(zhun)(zhun),与(yu)工(gong)(gong)件检(jian)(jian)漏(lou)(lou)(lou)(lou)(lou)时(shi)(shi)在(zai)(zai)(zai)检(jian)(jian)漏(lou)(lou)(lou)(lou)(lou)仪(yi)(yi)上显(xian)示(shi)的(de)(de)(de)(de)电(dian)量作(zuo)(zuo)(zuo)比(bi)(bi)对,再参照其它因(yin)素,按一(yi)(yi)(yi)定的(de)(de)(de)(de)公式即可算出(chu)工(gong)(gong)件的(de)(de)(de)(de)漏(lou)(lou)(lou)(lou)(lou)率。这(zhei)是(shi)确定工(gong)(gong)件漏(lou)(lou)(lou)(lou)(lou)率的(de)(de)(de)(de)基(ji)(ji)本(ben)方法。但有一(yi)(yi)(yi)点应(ying)特别强调(diao),被(bei)检(jian)(jian)工(gong)(gong)件的(de)(de)(de)(de)漏(lou)(lou)(lou)(lou)(lou)孔(kong)所处的(de)(de)(de)(de)检(jian)(jian)漏(lou)(lou)(lou)(lou)(lou)条(tiao)件应(ying)与(yu)标准(zhun)(zhun)漏(lou)(lou)(lou)(lou)(lou)孔(kong)所处的(de)(de)(de)(de)检(jian)(jian)漏(lou)(lou)(lou)(lou)(lou)条(tiao)件相同,这(zhei)样(yang)(yang)它们在(zai)(zai)(zai)检(jian)(jian)漏(lou)(lou)(lou)(lou)(lou)仪(yi)(yi)上显(xian)示(shi)的(de)(de)(de)(de)电(dian)量才好进(jin)行比(bi)(bi)对,以(yi)计算工(gong)(gong)件漏(lou)(lou)(lou)(lou)(lou)率的(de)(de)(de)(de)大(da)小。
检(jian)漏技(ji)术与仪器的相关技(ji)术指(zhi)标
随着航天技术的(de)发展,检(jian)漏技术也在不断(duan)取得进步。目(mu)前(qian)比(bi)较成熟的(de)检(jian)漏方法(fa)有喷(pen)吹法(fa)、氦(hai)罩法(fa)、充压法(fa)、吸枪法(fa)、探漏盒(he)法(fa)、累积检(jian)漏法(fa)、背压法(fa)及(ji)四极(ji)质谱检(jian)漏法(fa)。各种(zhong)方法(fa)都有其特点及(ji)适(shi)用(yong)条件(jian)。
在检(jian)(jian)(jian)漏(lou)(lou)实践中,由于(yu)我们(men)所(suo)遇到(dao)的(de)被检(jian)(jian)(jian)器(qi)件(jian)的(de)结构(gou)、大(da)小、要求等各(ge)(ge)不相同(tong),如何根据这些特定的(de)条件(jian)选择(ze)检(jian)(jian)(jian)漏(lou)(lou)方法(fa),这是检(jian)(jian)(jian)漏(lou)(lou)工作(zuo)(zuo)人员必须(xu)解(jie)(jie)决的(de)首要问题。因此,了解(jie)(jie)各(ge)(ge)种(zhong)检(jian)(jian)(jian)漏(lou)(lou)方法(fa)及其特点,熟练地运(yun)用(yong)它们(men)来(lai)满足被检(jian)(jian)(jian)器(qi)件(jian)的(de)检(jian)(jian)(jian)漏(lou)(lou)要求,这对于(yu)检(jian)(jian)(jian)漏(lou)(lou)工作(zuo)(zuo)人员来(lai)说是十分(fen)必要的(de)。另外(wai)许多检(jian)(jian)(jian)漏(lou)(lou)方法(fa)与仪器(qi)的(de)一些技(ji)术指标密(mi)切相关,对此我们(men)应有一定的(de)了解(jie)(jie)。本文主要介绍喷吹法(fa)和(he)背压法(fa)检(jian)(jian)(jian)漏(lou)(lou)技(ji)术。
在氦质谱(pu)检(jian)漏中,与检(jian)漏方法密切相关(guan)的仪器技术(shu)指(zhi)标(biao)主要有(you)以下几项:
（1）最(zui)小可检漏(lou)(lou)率(lv):当存在本底噪声时,将仪(yi)(yi)器(qi)调(diao)到“最(zui)佳”工(gong)作状态,纯示漏(lou)(lou)气体(ti)通(tong)过(guo)漏(lou)(lou)孔(kong)时,仪(yi)(yi)器(qi)所(suo)能检出的最(zui)小漏(lou)(lou)率(lv)(也就是(shi)以前所(suo)说(shuo)的仪(yi)(yi)器(qi)灵敏(min)度) 。最(zui)小可检漏(lou)(lou)率(lv)是(shi)氦质谱检漏(lou)(lou)仪(yi)(yi)最(zui)核心的技术指标。
（2）有效最小可检漏(lou)率:当存(cun)在本底噪声时(shi),仪器(qi)及外部(bu)检漏(lou)系统调到某一检漏(lou)工作(zuo)状态(可能有分(fen)(fen)流) ,当纯示漏(lou)气(qi)体通过漏(lou)孔时(shi),部(bu)分(fen)(fen)或全(quan)部(bu)示漏(lou)气(qi)体进入(ru)检漏(lou)仪,在此情况下所(suo)能检出的最小漏(lou)率(也就是以前(qian)所(suo)说(shuo)的检漏(lou)灵敏度) 。
（3）清(qing)除(chu)时间:从漏(lou)孔进(jin)气端停(ting)止施加(jia)示漏(lou)气体开始,到检(jian)漏(lou)仪净(jing)偏转值下降到最大(da)漏(lou)气信号的37%所经历(li)的时间。
在(zai)检(jian)(jian)(jian)漏(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)实践中(zhong),仪(yi)(yi)器(qi)的(de)(de)最(zui)(zui)(zui)小(xiao)可(ke)(ke)检(jian)(jian)(jian)漏(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)率(lv)(lv)(lv)(lv)与(yu)有(you)(you)效最(zui)(zui)(zui)小(xiao)可(ke)(ke)检(jian)(jian)(jian)漏(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)率(lv)(lv)(lv)(lv)应(ying)(ying)小(xiao)于(yu)工(gong)件(jian)的(de)(de)最(zui)(zui)(zui)大(da)允许漏(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)率(lv)(lv)(lv)(lv),通常(chang)选择高于(yu)被检(jian)(jian)(jian)工(gong)件(jian)最(zui)(zui)(zui)大(da)允许漏(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)率(lv)(lv)(lv)(lv)1～2数量级。在(zai)背(bei)压(ya)法检(jian)(jian)(jian)漏(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)中(zhong)明确有(you)(you)最(zui)(zui)(zui)小(xiao)可(ke)(ke)检(jian)(jian)(jian)漏(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)率(lv)(lv)(lv)(lv)限制(zhi);同(tong)时还(hai)有(you)(you)最(zui)(zui)(zui)大(da)可(ke)(ke)检(jian)(jian)(jian)漏(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)率(lv)(lv)(lv)(lv)限制(zhi)。在(zai)喷(pen)吹(chui)法检(jian)(jian)(jian)漏(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)中(zhong),反(fan)应(ying)(ying)时间与(yu)喷(pen)吹(chui)时间密切(qie)相关(guan),直(zhi)接影(ying)(ying)响(xiang)检(jian)(jian)(jian)测结(jie)果(guo)。在(zai)一(yi)些(xie)具(ju)有(you)(you)漏(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)率(lv)(lv)(lv)(lv)直(zhi)读(du)功能(neng)(neng)的(de)(de)检(jian)(jian)(jian)漏(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)仪(yi)(yi)使用(yong)过(guo)程中(zhong),当(dang)用(yong)户在(zai)调(diao)(diao)试检(jian)(jian)(jian)漏(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)仪(yi)(yi)时,打开标(biao)准(zhun)漏(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)孔,仪(yi)(yi)器(qi)会有(you)(you)一(yi)漏(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)率(lv)(lv)(lv)(lv)显示(shi)值,若显示(shi)的(de)(de)漏(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)率(lv)(lv)(lv)(lv)数值与(yu)标(biao)准(zhun)漏(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)孔的(de)(de)标(biao)称值不(bu)(bu)符,可(ke)(ke)以调(diao)(diao)整检(jian)(jian)(jian)漏(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)仪(yi)(yi)上的(de)(de)某些(xie)参数,使其(qi)相符,则检(jian)(jian)(jian)漏(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)仪(yi)(yi)就(jiu)(jiu)具(ju)备了(le)所(suo)谓的(de)(de)直(zhi)读(du)功能(neng)(neng)。这就(jiu)(jiu)带(dai)来一(yi)个(ge)问题(ti):为了(le)调(diao)(diao)整到(dao)数值相同(tong),往(wang)往(wang)要(yao)(yao)牺牲检(jian)(jian)(jian)漏(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)仪(yi)(yi)的(de)(de)最(zui)(zui)(zui)小(xiao)可(ke)(ke)检(jian)(jian)(jian)漏(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)率(lv)(lv)(lv)(lv),比如一(yi)台检(jian)(jian)(jian)漏(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)仪(yi)(yi)的(de)(de)最(zui)(zui)(zui)小(xiao)可(ke)(ke)检(jian)(jian)(jian)漏(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)率(lv)(lv)(lv)(lv)在(zai)各项(xiang)参数调(diao)(diao)到(dao)最(zui)(zui)(zui)佳状(zhuang)态时可(ke)(ke)达1 ×10- 12 Pa·m3/s,当(dang)为了(le)调(diao)(diao)整仪(yi)(yi)器(qi)的(de)(de)某些(xie)参数使其(qi)可(ke)(ke)以直(zhi)读(du)时,其(qi)最(zui)(zui)(zui)小(xiao)可(ke)(ke)检(jian)(jian)(jian)漏(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)率(lv)(lv)(lv)(lv)可(ke)(ke)能(neng)(neng)就(jiu)(jiu)增大(da)到(dao)1 ×10- 10 Pa ·m3/s了(le),其(qi)灵敏度降(jiang)低。当(dang)然,对(dui)于(yu)漏(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)率(lv)(lv)(lv)(lv)指(zhi)标(biao)比较大(da)的(de)(de)工(gong)件(jian),并(bing)不(bu)(bu)受影(ying)(ying)响(xiang);但当(dang)工(gong)件(jian)漏(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)率(lv)(lv)(lv)(lv)要(yao)(yao)求很小(xiao)时,就(jiu)(jiu)可(ke)(ke)能(neng)(neng)影(ying)(ying)响(xiang)检(jian)(jian)(jian)漏(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)的(de)(de)进行,遇到(dao)这种情况,就(jiu)(jiu)应(ying)(ying)将检(jian)(jian)(jian)漏(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)仪(yi)(yi)的(de)(de)各项(xiang)参数调(diao)(diao)到(dao)最(zui)(zui)(zui)佳位置,充(chong)分发挥其(qi)灵敏度,不(bu)(bu)要(yao)(yao)拘泥于(yu)检(jian)(jian)(jian)漏(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)(lou)仪(yi)(yi)还(hai)能(neng)(neng)不(bu)(bu)能(neng)(neng)直(zhi)读(du)。
