通過改變UV燈電源電壓(ya)來(lai)測量不同放電電流時的燈管電壓(ya)V，就可得(de)到如(ru)下圖所示UV燈電壓(ya)-電流關系(xi)曲(qu)線(xian)，此(ci)曲(qu)線(xian)稱為氣(qi)體放電的全伏(fu)-安特(te)性曲(qu)線(xian)。

氣體放電的全伏-安(an)特性曲線

觀察UV燈電器柜(ju)上(shang)的(de)電壓、電流表，將每一瞬時(shi)數據記錄下來繪成曲(qu)(qu)線就是上(shang)圖曲(qu)(qu)線。下面來分析燈管(guan)內帶電粒(li)子的(de)運(yun)動(dong)過(guo)程(cheng)來解釋這個(ge)曲(qu)(qu)線。曲(qu)(qu)線各段(duan)對應(ying)的(de)粒(li)子運(yun)動(dong)過(guo)程(cheng)是：

首先電(dian)(dian)(dian)源（一般用(yong)漏磁(ci)變(bian)壓(ya)器(qi)）啟動，此時(shi)燈內(nei)無導電(dian)(dian)(dian)物質（電(dian)(dian)(dian)極(ji)內(nei)電(dian)(dian)(dian)子(zi)發射材料不(bu)能立刻發出(chu)電(dian)(dian)(dian)子(zi)），變(bian)壓(ya)器(qi)處(chu)于開(kai)路狀態，電(dian)(dian)(dian)極(ji)上個別(bie)電(dian)(dian)(dian)子(zi)逸出(chu)電(dian)(dian)(dian)極(ji)表面，在外電(dian)(dian)(dian)場作用(yong)下電(dian)(dian)(dian)子(zi)被加速形成(cheng)電(dian)(dian)(dian)流(liu)，這就是OA段。

當大量的電(dian)子(zi)逸出(chu)電(dian)極表(biao)面在電(dian)場加速(su)下全部(bu)到達正極，這時電(dian)流就飽和了(le)，而燈(deng)管(guan)電(dian)壓迅速(su)升高，這就是AB段(duan)。當電(dian)源電(dian)壓再升髙，電(dian)子(zi)速(su)度增(zeng)大與燈(deng)管(guan)內氬氣原子(zi)碰(peng)撞(zhuang)使之電(dian)離，電(dian)離后的電(dian)子(zi)被電(dian)場加速(su)又與其(qi)他氬原子(zi)碰(peng)撞(zhuang)形成(cheng)更多離子(zi)。這樣一(yi)種繁衍過程使電(dian)子(zi)數雪崩式地增(zeng)加，形成(cheng)BC段(duan)雪崩放電(dian)。

雪崩放電使(shi)燈(deng)(deng)管(guan)(guan)電流(liu)迅速增加就是圖(tu)中CD段。在C點燈(deng)(deng)內汞或金(jin)屬被(bei)碰(peng)撞也受激電離形成氣體，此(ci)時(shi)燈(deng)(deng)內離子增多而電阻減小，燈(deng)(deng)管(guan)(guan)電壓(ya)(ya)(ya)下降。在C點氣體開(kai)始(shi)放電稱為(wei)氣體放電的(de)破裂點或著(zhu)火點，相應的(de)電壓(ya)(ya)(ya)Vz稱為(wei)燈(deng)(deng)管(guan)(guan)的(de)點火電壓(ya)(ya)(ya)。而變壓(ya)(ya)(ya)器的(de)開(kai)路電壓(ya)(ya)(ya)或稱為(wei)啟(qi)動電壓(ya)(ya)(ya)要大于(yu)Vz才能(neng)使(shi)燈(deng)(deng)管(guan)(guan)啟(qi)輝光。此(ci)時(shi)放電能(neng)自我維(wei)持不需電極(ji)發射(she)電子激發氣體。

在(zai)EF段維持(chi)正常輝(hui)光放電(dian)(dian)，此時電(dian)(dian)流(liu)(liu)增(zeng)加(jia)但(dan)管(guan)(guan)壓(ya)不(bu)變，這是因為陰極并(bing)未全部(bu)用于(yu)發(fa)射(she)。隨(sui)著(zhu)電(dian)(dian)流(liu)(liu)增(zeng)大(da)(da)，陰極全部(bu)參與(yu)發(fa)射(she)電(dian)(dian)弧(hu)，陰極電(dian)(dian)流(liu)(liu)密度上升，從F點后(hou)管(guan)(guan)壓(ya)上升，這就進入(ru)異常輝(hui)光放電(dian)(dian)階(jie)段FG。電(dian)(dian)流(liu)(liu)再(zai)增(zeng)加(jia)電(dian)(dian)極溫(wen)度上升轉入(ru)熱電(dian)(dian)子(zi)發(fa)射(she)，此時管(guan)(guan)壓(ya)迅(xun)速下降，電(dian)(dian)流(liu)(liu)迅(xun)速增(zeng) 加(jia)，形成了弧(hu)光放電(dian)(dian)的GH段。這段是負伏-安特(te)性，隨(sui)著(zhu)電(dian)(dian)流(liu)(liu)無限增(zeng)大(da)(da)電(dian)(dian)極會被擊(ji)毀，而UV燈正是工作(zuo)在(zai)該弧(hu)光放電(dian)(dian)段。

輝光放電(dian)(dian)(dian)是燈工作于高電(dian)(dian)(dian)壓(ya)、小(xiao)電(dian)(dian)(dian)流(liu)狀態，當UV燈通電(dian)(dian)(dian)后觀察電(dian)(dian)(dian)壓(ya)表，此時(shi)(shi)的電(dian)(dian)(dian)壓(ya)值(zhi)為變壓(ya)器開(kai)路電(dian)(dian)(dian)壓(ya)，電(dian)(dian)(dian)流(liu)為零(ling)。一段時(shi)(shi)間后燈發(fa)出(chu)輝光，此時(shi)(shi)電(dian)(dian)(dian)壓(ya)下(xia)降(jiang)、電(dian)(dian)(dian)流(liu)慢慢上升，突然燈大(da)亮，電(dian)(dian)(dian)流(liu)迅速(su)增加、電(dian)(dian)(dian)壓(ya)下(xia)降(jiang)，這時(shi)(shi)為弧光放電(dian)(dian)(dian)。