低能质子束在氢等离子体中的能损研究
|
摘要
实验测量了100 keV的质子束穿过部分电离氢等离子体靶后的能量损失.等离子体靶由气体放电方式产生,其自由电子密度在1016cm-3量级,电子温度约1—2 eV,维持时间在微秒量级.研究结果表明:质子束在等离子体靶中的能量损失与自由电子密度密切相关且明显大于在同密度条件下中性气体靶中的能量损失;在自由电子密度达到峰值处,通过实验结果计算得到此时的自由电子库仑对数约为10.8,与理论计算结果符合较好,该值比Bethe公式给出的中性气体靶中束缚电子库仑对数高4.3倍,相应的能损增强因子为2.9.
Energy loss of protons with energy 100 ke V penetrating the partially ionized hydrogen plasma target was measured.The plasma target was created by electric discharge in the hydrogen gas, the state of the plasma target was diagnosed by using the laser interferometry method: the free electron density is up to 1016cm-3, temperature is about 1–2 e V,and the plasma target may exist at the microsecond level. It is found that the energy loss of protons is closely related to the free electron density, and the energy loss data enable us to infer the value of the Coulomb logarithm(10.8) for the stopping power of the free electrons. This agrees well with the theoretical prediction which is 4.3 times higher than that given by the Bethe formula for neutral hydrogen, which is a little bigger than Hoffmann's result but much smaller than Jacoby's result. Comparing our result with Hoffmann's, the energy we used is only 100 ke V, much lower than 1.4Me V/u, and the low-energy regime we applied could be the cause of the increase in the enhancement factor. However,in the comparison between our result and the Jacoby's, the effective charge for protons is almost constant, unlike the Kr+impact in wihch the enhanced ion charge state induces the giant enhancement factor. Compared to the gas target,the energy loss enhancement factor in plasma target is 2.9.
Energy loss of protons with energy 100 ke V penetrating the partially ionized hydrogen plasma target was measured.The plasma target was created by electric discharge in the hydrogen gas, the state of the plasma target was diagnosed by using the laser interferometry method: the free electron density is up to 1016cm-3, temperature is about 1–2 e V,and the plasma target may exist at the microsecond level. It is found that the energy loss of protons is closely related to the free electron density, and the energy loss data enable us to infer the value of the Coulomb logarithm(10.8) for the stopping power of the free electrons. This agrees well with the theoretical prediction which is 4.3 times higher than that given by the Bethe formula for neutral hydrogen, which is a little bigger than Hoffmann's result but much smaller than Jacoby's result. Comparing our result with Hoffmann's, the energy we used is only 100 ke V, much lower than 1.4Me V/u, and the low-energy regime we applied could be the cause of the increase in the enhancement factor. However,in the comparison between our result and the Jacoby's, the effective charge for protons is almost constant, unlike the Kr+impact in wihch the enhanced ion charge state induces the giant enhancement factor. Compared to the gas target,the energy loss enhancement factor in plasma target is 2.9.
引文
[1]Bohr N 1913 Philos.Mag.25 10
[2]Bethe H 1930 Ann.Phys.397 325
[3]Bloch F 1933 Ann.Phys.408 425
[4]Grande P L,Schiwiztz G 1998 Phys.Rev.A 58 3796
[5]Sigmund P,Schinner A 2000 Eur.Phys.J.D 12 425
[6]Zhao Y T,Hu Z H,Cheng R,Wang Y Y,Peng H B,Golubev A,Zhang X A,Lu X,Zhang D C,Zhou X M,Wang X,Xu G,Ren J R,Li Y F,Lei Y,Sun Y B,Zhao J T,Wang T S,Wang Y N,Xiao G Q 2012 Laser and Particle Beams 30 679
[7]Luo Z M,Teng L J 1982 Acta Phys.Sin.31 1166(in Chinese)[罗正明,滕礼坚1982物理学报31 1166]
[8]Wang Y N,Ma T C,Gong Y 1993 Acta Phys.Sin.42631(in Chinese)[王友年,马滕才,宫野1993物理学报42631]
[9]Hoffmann D H H,Weryrich K,Wahl H 1990 Phys.Rev.A 45 2313
[10]Li X M,Shen B F,Cha X J,Fang Z B,Zhang X M,Jin Z Y,Wang F C 2006 Acta Phys.Sin.55 2313(in Chinese)[李雪梅,沈百飞,查学军,方宗豹,张晓梅,金张英,王凤超2006物理学报55 2313]
[11]Servajean A,Gardes D,Bimbot R 1992 J.Appl.Phys.71 2587
[12]Kuznetsov A P,Byalkovskii O A,Gavrilin R O 2013Plasma Phys.Rep.39 248
[13]Belyaev G,Basko M,Cherkasov A 1996 Phys.Rev.E2701
[14]Young F C,Mosher D,Stephanakis S J 1982 Phys.Rev.Lett.49 549
[15]Hoffmann D H H,Weyrich K,Wahl H 1990 Phys.Rev.A 42 2313
[16]Jacoby J,Hoffmann D H H,Laux W 1995 Phys.Rev.Lett.74 1550
[17]Li Y F,Zhao Y T,Cheng R,Peng H B,Zhou X M,Li J Y,Yu Y,Wang X,Ren J R,Wang Y Y,Lei Y,Sun Y B,Liu S D 2014 Nucl.Phys.Rev.31 120(in Chinese)[李永峰,赵永涛,程锐,彭海波,周贤明,李锦钰,虞洋,王兴,任洁茹,王瑜玉,雷瑜,孙渊博,刘世东2014原子核物理评论31 120]
[18]Hu Z H,Song Y H,MikoviZ L 2011 Laser and Particle Beams 29 299
[19]Ziegler J F http://www.srim.org[2014-10-15]
[20]Larkin A I 1960 Zh.Eksp.Teor.Fiz.37 186
[2]Bethe H 1930 Ann.Phys.397 325
[3]Bloch F 1933 Ann.Phys.408 425
[4]Grande P L,Schiwiztz G 1998 Phys.Rev.A 58 3796
[5]Sigmund P,Schinner A 2000 Eur.Phys.J.D 12 425
[6]Zhao Y T,Hu Z H,Cheng R,Wang Y Y,Peng H B,Golubev A,Zhang X A,Lu X,Zhang D C,Zhou X M,Wang X,Xu G,Ren J R,Li Y F,Lei Y,Sun Y B,Zhao J T,Wang T S,Wang Y N,Xiao G Q 2012 Laser and Particle Beams 30 679
[7]Luo Z M,Teng L J 1982 Acta Phys.Sin.31 1166(in Chinese)[罗正明,滕礼坚1982物理学报31 1166]
[8]Wang Y N,Ma T C,Gong Y 1993 Acta Phys.Sin.42631(in Chinese)[王友年,马滕才,宫野1993物理学报42631]
[9]Hoffmann D H H,Weryrich K,Wahl H 1990 Phys.Rev.A 45 2313
[10]Li X M,Shen B F,Cha X J,Fang Z B,Zhang X M,Jin Z Y,Wang F C 2006 Acta Phys.Sin.55 2313(in Chinese)[李雪梅,沈百飞,查学军,方宗豹,张晓梅,金张英,王凤超2006物理学报55 2313]
[11]Servajean A,Gardes D,Bimbot R 1992 J.Appl.Phys.71 2587
[12]Kuznetsov A P,Byalkovskii O A,Gavrilin R O 2013Plasma Phys.Rep.39 248
[13]Belyaev G,Basko M,Cherkasov A 1996 Phys.Rev.E2701
[14]Young F C,Mosher D,Stephanakis S J 1982 Phys.Rev.Lett.49 549
[15]Hoffmann D H H,Weyrich K,Wahl H 1990 Phys.Rev.A 42 2313
[16]Jacoby J,Hoffmann D H H,Laux W 1995 Phys.Rev.Lett.74 1550
[17]Li Y F,Zhao Y T,Cheng R,Peng H B,Zhou X M,Li J Y,Yu Y,Wang X,Ren J R,Wang Y Y,Lei Y,Sun Y B,Liu S D 2014 Nucl.Phys.Rev.31 120(in Chinese)[李永峰,赵永涛,程锐,彭海波,周贤明,李锦钰,虞洋,王兴,任洁茹,王瑜玉,雷瑜,孙渊博,刘世东2014原子核物理评论31 120]
[18]Hu Z H,Song Y H,MikoviZ L 2011 Laser and Particle Beams 29 299
[19]Ziegler J F http://www.srim.org[2014-10-15]
[20]Larkin A I 1960 Zh.Eksp.Teor.Fiz.37 186