IN MAGISTRI BADAREU MEMORIAM

THE WORKS AND THE SCHOOL OF EUGEN BADAREU

by Acad. Prof. Dr. Ioan-Iovitz Popescu
 
 


Descendant from an old Moldavian family originating in the village Badarai upon Prut river, educated within high schools of Austria and Italy, Eugen Badareu entered the scientific life at the same time with the great discoveries occurring in Physics at the beginning of this century. The perturbations caused by the First World War plunged him from Pisa up to Sankt Petersburg, but he soon came back to Cernauti and then, finally, to Bucharest. He has been irresistibly attracted by the universe of phenomena occurring by the passage of electricity through gases. Therefore, the investigation of ionized gases and plasmas became the major scientific direction of the great school of physics he created along more than 60 years of patient endeavour. His illustrious disciples themselves who, in their turn, have built up new research schools, such as Herbert Mayer (thin films), Radu Grigorovici (amorphous semiconductors), Margareta Giurgea (liquid crystals), Liviu Constantinescu (geophysics), began their researches in physics with electrical discharges in gases. As a matter of fact, the school of Eugen Badareu has rather been proved in the long run to be a school of school creators, and the man Badareu revealed himself to be more than a great teacher and scientist - he was a line of force, a spirit and an epoch dominating the Romanian physics in this ending century.

I had the extraordinary chance to be for more than 20 years a close disciple and co-worker of the Magister Badareu, of which I was very tight bound both professionally and emotionally. I was his student, then preparator and assistant at his famous lectures on acoustics, optics, and electrical gas discharges. Alike all my generation colleagues -  who remained within Badareuís school main stream - I can say that I breathed the atmosphere Badareu and that the results and position I presently enjoy are due primarily to him. In the following, I will try to present the most important moments of the scientific life of my professor and mentor Eugen Badareu.
 


BIOGRAPHY

Born: September 19 (October 2) 1887, Ismail. Died:  March 11, 1975, Bucharest. Nationality: Romanian. Religion: Christian orthodox. Citizenship: Russian, then Romanian (after his coming to Cernauti in 1921). Education: Lyceum in Ismail and Chisinau, graduated in Ismail (1905). Continues his superior studies at Technische Hochschule in Graz (1905-1907) and then at Scuola Normale Superiore della Universià di Pisa (1907-1911); assistant of Prof. Antonio Pacinotti until the death of the later in 1912. In the same year he obtained his doctor in science degree with Prof. Angello Battelli, who was at that time the director of Istituto di Fisica della Universià di Pisa. In his doctor thesis, entitled "The Dielectric Constant of Gases and of Gas Mixtures", Eugen Badareu performed a thorough experimental proof of the molecular polarisation theory of the dielectric constant, respectively of Clausius-Mosotti relationship for air and nitrogen up to pressures of 350 atmospheres. Career: In January 1911 starts his scientific and didactic activity as assistant at the Institute of Physics of the Pisa University and publishes the first scientific paper (1912). The outbreak of World War I (1914) obliges the young Eugen Badareu to come back to Russia. He chooses the Faculty of Sciences of the Sankt Petersburg University, where is welcomed by Prof. O. D. Chwolson, the director of the Institute of Physics of the university. He has been appointed as assistant of both Prof. A. F. Ioffe (1914-1918) and Prof. D. S. Rojdestvenskii (1918-1920) and obtains the docent title (1918). He became soon the co-founder, jointly with D. S. Rojdestvenskii, of the State Optical Institute of Sankt Petersburg, professor of optics and photo-technique, and an instituteís department head (1917-1920). At the height of the civil war, he hardly succeeds to cross the Ukraine and to reach Romania (1920). He is welcomed at the University of Cernauti, where he is appointed as professor for experimental physics at the Faculty of Sciences and director of the Institute for Experimental Physics of the Cernauti University (1921-1934). Here also accomplishes the function of associate professor at the Chair of Theoretical Physics (1922-1928) and dean of the Faculty of Sciences (1926-1928). Considered to be the most important representative of the "School of Cernauti", he has been invited at the Faculty of Sciences of the Bucharest University as a successor of Constantin Miculescu (1863-1937) and appointed there as professor and Chief of the Chair and Laboratory of Molecular Physics, Acoustics and Optics (1935-1964). He was founding member of the Romanian Academy of Sciences (1935), full member of the Romanian Academy (1948), founder and president of the Acoustic Commission of the Romanian Academy (1955), chief of the Optics and Spectroscopy Department (1949-1956) and president of the Scientific Council within the Institute of Physics at Magurele of the Romanian Academy (1949-1956). Finally, he became the director of the Institute of Physics at Bucharest of the Romanian Academy (1956-1970). Eugen Badareu organized the first great international event in physics in Romania: the IX-th International Conference on Phenomena in Ionised Gases (ICPIG IX), Bucharest, 1969 (with a number of 800 participants from 32 countries). Distinctions: Romaniaís Crown in Commander rank and Cultural Merit for Sciences (before World War II), then First Class Labour Order (1957, 1960), Honoured Scientist (1962), and First Class Scientific Merit Order (1966).
 

ABBREVIATIONS OF JOURNAL TITLES

AP = Annalen der Physik
APL = Applied Physics Letters
BFSC = Bulletin of the Faculty of Sciences of Cernauti (in Romanian)
BJAP = British Journal of Applied Physics
BRPS = Bulletin of the Romanian Physics Society (in Romanian)
BSRP = Bulletin de la Société Roumaine de Physique
DMP = Disquisitiones Mathematicae et Physicae, Bucharest
CRP = Comptes Rendus des Séances de l'Académie des Sciences (Paris)
GSSRA = General Scientific Session of the Romanian Academy (in Romanian)
ICPIG = International Conference on Phenomena in Ionised Gases
JCP = Journal of Chemical Physics
JEC = Journal of Electronics and Control
JPR = Le Journal de Physique et le Radium
NC = Nuovo Cimento;
OC = Optics Communications
PR = Physical Review
PRL = Physical Review Letters
PZ =  Physikalische Zeitschrift
RACP = Romanian Academy Communications, Physics (in Romanian)
RAL = Rendiconti della Accadmia dei Lincei
RRP = Revue (Roumaine) de Physique, Romanian Academy
SBRA = Scientific Bulletin of the Romanian Academy, Ser. Math. Phys. (in Romanian)
SRP = Studies and Researches in Physics, Romanian Academy (in Romanian)
ZP = Zeitschrift für Physik
ZPC = Zeitschrift für physikalische Chemie
ZPCU = Zeitschrift für den physikalischen und chemischen Unterricht
ZTP = Zeitschrift für technische Physik
 


WORKS , STUDENTS AND COLLABORATORS

Eugen Badareu is considered the founder of the first Romanian school of electrical discharges in gases and plasma physics. His outstanding activity in physics is unfolding on a period exceeding 60 years (1911-1975). For convenience, we distinguish in his activity several stages.

The Italian Period at Pisa (1907-1914)

Student at the Superior Normal School (1907-1911) and assistant of the Institute of Physics of the Pisa University (1912-1914), doctor in sciences, under the scientific guidance of Prof. A. Battelli, with a thesis on the dielectric constant of gases and of gas mixtures (1912). His scientific mentors were Prof. A. Pacinotti (inventor of the electrical dynamo, jointly with Z.-T. Gramme) and Prof. A. Battelli (director of the Institute of Physics) and the closest co-worker A. Occhialini (the father of G. P. S. Occhialini, credited, together with C. D. Anderson (1932) and P. M. S. Blackett (1933) with the positron discovery). The young E Bodareu (as he signed the papers in this period), brought his first scientific contribution (1911-1913) by the experimental proof of the Clausius-Mosotti theory of the dielectric constant based on the molecular polarisation for air and nitrogen up to pressures of 350 atmospheres: La costante dielettrica dell'aria fino a 200 atmosfere (with A. Occhialini), NC, IV, 3-28 (1912); La costante dielettrica dell'aria fino a 350 atmosfere (with A. Occhialini), RAL, XXII, 597-603 (1913); La costante dielettrica dell'azoto ad alta pressione, RAL, XXII, 480-482 (1913); La compressibilità del clorure di metile, RAL, XXII, 491-493 (1913); Die Dielektrizitätskonstante der Luft bis zu 350 Atmosphären aufwärts (with A. Occhialini), AP, 42, 67-93 (1913). Citations: Dielectric Constant Tables of Landolt-Börnstein.

The Russian Period at Sankt Petersburg (1915-1920)

Assistant of Prof. A. F. Ioffe (1914-1918) and of Prof. D. S. Rojdestvenskii (1918-1920), and docent (1918) at the Faculty of Sciences and at the Institute of Physics (director Prof. O. D. Chwolson) of the Sankt Petersburg University. Founder, jointly with Prof. D. S. Rojdestvenskii, of the State Optical Institute of Sankt Petersburg, where he acted as professor of optics, photo-techniques and department head (1917-1918). His scientific mentors in this period were Prof. O. D. Chwolson (the author of the well-known Treatise of Physics), Prof. A. F. Ioffe (one of the forerunners of semiconductor physics), Prof. D. S. Rojdestvenskii (the author of the interferential method of "hooks"). In this period, Eugen Badareu devoted himself to optics research and specially to interferometry and induced birefringence by Kerr effect: The Interferometer Badareu-Rojdestvenskii, communicated at the First Science Congress of Petersburg (1918); Ob absoliutnom znacenii elektriceskovo iavleniia Kerra, Protokoly Zasedanii S'iezda Fizikov v Petrograde, 4-7 fevralia 1919, Jurnal Russkovo Fiziko-Himiceskovo Obscestva, 51, 349-350 (1919); On the Absolute Value of the Electrical Double Refraction (this paper has been signed with the name E. Badareu), Memories of the Romanian Academy, Scientific Section, 1, 1-6 (1923).

The Bucovinean Period at Cernauti (1921-1934)

. On January 1st, 1921, we find him appointed within the University of Cernauti as professor of experimental physics at the Faculty of Sciences and director of Institute for Experimental Physics, that he re-organizes and rises at an European scientific level. He became soon the most remarkable representative of the "School of Cernauti". We shall first be concerned with his first doctors in physics: Herbert Mayer (1900-1992), doctor in physical sciences since 1926 at Prof. E. Badareu with a thesis regarding ion mobilities in gas mixtures: follows specialization stages in Tübingen with Prof. W. Gerlach (1928) and in Bristol with Prof. A. M. Tyndall (1932), devoting himself to the physics of surfaces and of thin films; left Cernauti in 1940 and continued his activity in Germany, where he has eventually been appointed as director of the Institute of Physics (since 1950) and as professor at Technische Hochschule für Bergbau und Hüttenwesen in Clausthal-Zellerfeld (rector 1956-1958), and elected member of the Academy of Sciences of Göttingen (1960); author of the first treatise on the physics of thin films and considered as the father of this research field, namely Physik Dünner Schichten, Stuttgart, Vol.1 (1950) and Vol.2 (1955) - the first volume being dedicated to his teacher E. Badareu. Theodor Câmpan (1899-1960), doctor in physical sciences since 1929 at Prof. E. Badareu, with a thesis dedicated to gas ionization phenomena; in 1940, he moved to Iassy where he became professor of electricity and thermotechnique at the Electrotechnical Faculty (dean 1948-1952) of the Polytechnic Institute. Radu Grigorovici (b. 1911), bachelor of chemical (1931) and physical (1933) sciences, preparator (1933-1934); in the fall of 1934 he follows his teacher E. Badareu to the University of Bucharest, where he obtains the title of doctor in physical sciences with a thesis entitled The breakdown potential in mercury vapours, asserted on December 8, 1938; brilliant university didactic and research career (1934-1960), head of the semiconductor department (1960-1964), scientific deputy director (1964-1974) of the Institute of Physics at Bucharest and then of the Institute of Physics and Materials Technology at Magurele, he is considered as a forerunner of the amorphous semiconductor research; has been elected corresponding member (1963), full member (1990) and vice-president (1990-1994) of the Romanian Academy. Other early co-workers of Prof. E. Badareu: Aurel Munteanu (1908-1965), bachelor of physics in 1930, preparator (1930-1932), obtains the title of doctor in physical sciences with Prof. Aimé Cotton in Paris with a thesis on the spectroscopy of organic substances; didactic career at the Polytechnic Institute of Bucharest (since 1949) and research works at Institute of Atomic Physics in Magurele. Dionisie Hacman (1912-1984), bachelor (1932), preparator during the university years (1931), assistant (1935), he worked initially under Prof. E. Badareu supervision; after the departure of his teacher to Bucharest, he continues under the scientific guidance of Prof. H. Mayer and obtains the doctoral degree with a thesis on the optical properties of thin films of alkaline metals (1939); in 1940 he sheltered for a short time in Bucharest, where we find him as an assistant at the chair of Prof. E. Badareu, then, in 1941, moved at the Technische Hochschule in Berlin-Charlottenburg, within the chair of physics of Prof. O. Haxel, and finally (since 1947), hired at the well-known Balzers A. G. Company in Liechtenstein. Gheorghe Maciuc (b. 1905), bachelor in 1929, assistant (1930-1940), co-worker of Prof. E. Badareu and then of Prof. H. Mayer; after 1940 he succeeded to emigrate to the United States of America. George Macrin (1911-1991), was for a long period (1948-1980) the head of the technical department of electric lamp enterprises Steaua Electrica from Fieni, Electrofar from Bucharest and Romlux from Targoviste; he wrote very important manuscripts about Bucovina, among them we mention Scoala de fizica de la Cernauti, 78 pages (1985/1986).

By his scientific work covering this period, Eugen Badareu may be considered as the founder of the Romanian school of electrical discharges in gases. In this domain he performed pioneering works on: positive ion sources, secondary electron emission from solid bodies, breakdown potentials of glow discharges, wall charging effects (pseudo-vacuum effect, positive column stratification), hot electrode effects, kinetic energy demonstration of channel rays (1931, a micro-propeller device of 17 mg weight only, multiplied and distributed by Leybold Company from Köln for didactic demonstrations), glow discharges with command electrode (1933-1934, a composite cathode consisting of a grid and a massive plate, allowing the control of the main discharge current by applying low electrical tensions between them). Starting with 1924, all papers with his authorship and published in foreign languages will be signed with the name E. Badareu: Über die durch Kationenstöbe aus Platin ausgelösten Elektronenströme im Hochvakuum, PZ, 25, 137-140 (1924); Über die Wirkung der Stöbe langsamer Kationen auf Lithiumchlorid im Hochvakuum, PZ, 27, 634-637 (1926); Einige Bemerkungen über Ionenquellen, die positive Ionen aussenden, BFSC, 1, 1-10 (1927); Sur l'énergie cinétique des thermoions positifs émis par AlPO4, BFSC, 1, 2-4 (1927); On the cathode fall, BRPS, XXIX, 3-8 (1926-1927); Über die Sekundäremission aus festem Körpern, welche durch Stöbe von Partikeln verschiedener Natur erregt wird, BFSC, 2, 97 (1928); Einige Versuche über die Zündspannung der Glimmentladung bei erhitzter Anode, BFSC, 2, 193-197 (1928); Über die Zündspannung der Glimmentladung bei erhitzter Anode in Wasserstoff, BFSC, 2, 326 (1928); Beitrag zum Studium der Gasentladungen. I. Charakteristiken der Entladungen in Wasserstoff und Stickstoff bei reduzierten Drucken und Verwendung einer Glühkathode, BFSC, 3, 221-236 (1929); Beitrag zum Studium der Gasentladungen. II. Einige Beobachtungen über den Einflub der thermischen Behandlung der Elektroden auf die Glimmentladung, BFSC, 2, 304-306 (1928); Über den Einflub der Gasbeladung der Kathode auf die Zündspannung der Glimmentladung in Wasserstoff, BFSC, 3, 1-8 (1929); Über die Charakteristik der Gasentladung bei sehr tiefen Drucken, BFSC, 3, 88-90 (1929); Beitrag zum Studium der Gasentladungen. III. Über einige Änderungen der Zündspannung in Stickstoff und über die Ursachen derselben, BFSC, 4, 32-49 (1930); Über den Einflub  von Wandladungen auf die Zündspannung der Gase, BFSC, 5, 64-70 (1931); Versuche über das Pseudohochvakuum, ZTP, 12, Nr.6, 298-303 (1931); Vorlesungsversuch zur demonstration der Energie der Kanalstrahlen, ZPCU, 44, 217-218 (1931); Über den Einflub der Wandladungen und der Glaswände auf die charakteristischen Gröb en der Glimmentladung, BFSC, 6, 1-17 (1932); Über die Steuerung und Auslöschung einer Glimmentladung in einem Rohr mit Netzkathode und dritter Elektrode, ZTP, 14, Nr.12, 540-543 (1933); Sur un tube décharge à électrode de commande, BSRP, 36, 1-5 (1934); L'influence des parois en verre sur l'établissement des stratifications de la colonne positive (with G. Maciuc), JPR, 6, 365-368 (1935). From this period we can also point out the contributions of Herbert Mayer to ion mobilities in gas mixtures and of Theodor Câmpan to secondary electron emission and ionic current at the cathode of glow discharges: Contributions to ion mobility in electro-negative mixtures (H. Mayer), BRPS, XXIX, doctorate thesis with 61 pages (1926-1927); Zur Beweglichkeit in Gasmischungen (H. Mayer), PZ, 28, 637 (1927); Beitrag zum Studium der Gasionisation durch positive Ionen und der Sekundäremission aus Platin (T. I. Câmpan), PZ, 30, 858-865 (1929); Der Einflub elektrischer Entladungen auf die Sekundäremission der Kathode (T. I. Câmpan), PZ, 32, 593-597 (1931); Über die Stromverteilung an der Kathode einer Glimmentladung (T. I. Câmpan), ZP, 91, 111-123 (1934). Citations: Rudolf Seeliger, Handbuch der Experimentalphysik, 13, p. 603; Rudolf Seeliger, Einführung in die Physik der Gasentladungen (1934); Poggendorffs Biogr. Handwörterbuch VI, p.102 (1936).

First Bucharest Period (1935-1944)

Invited at the Faculty of Sciences of the Bucharest University as a successor of Constantin Miculescu (1863-1937), E. Badareu is officially transferred on January 1st, 1935 as professor and head of the Chair and of the Laboratory of Molecular Physics, Acoustics and Optics. In this period, under his direction, upheld their doctor degree in physical sciences several co-workers and former students, among which we remind: Radu Grigorovici, doctor (1938), corresponding member (1963), full member (1990) and vice-president (1990-1994) of the Romanian Academy; Liviu Constantinescu, doctor (1941), corresponding member (1963) and full member (1990) of the Romanian Academy; Margareta Valeriu (Giurgea), doctor (1943), corresponding member (1991) and full member (1992) of the Romanian Academy; and Gheorghe Bratescu, doctor (1944), successor at the Optics chair board. As per the Bucharest University 1940-1942 Yearbook, the members of Prof. E. Badareuís chair were the lecturers Stefan Vencov (appointed November 1st, 1923) and Gheorghe Cristescu appointed September 1st, 1926) and assistants Radu Titeica (appointed October 1st, 1934), Radu Grigorovici (appointed October 17, 1934), Gheorghe Manu (appointed April 1st, 1935), Margareta Valeriu (Giurgea) (appointed April 1st, 1937), Gheorghe Giurgea (appointed April 1st, 1937) and Liviu Constantinescu (appointed November 15, 1941); lasting collaborations with the Chair had also Dumitru Stefanescu and Emanoil Lucatu. During this period, Eugen Badareu and his co-workers brought important contributions regarding the electrical breakdown of gases: Remarques sur le potentiel explosif dans la vapeur de benzène, CRP, 207, 279 (1938); Le potentiel explosif dans la vapeur de benzène (with L. Constantinesco), CRP, 207, 217 (1938); Etude du potentiel explosif dans la vapeur des hydrocarbures (with L. Constantinescu), BSRP, 39, 3-29 (1938); Etude du potentiel explosif dans la vapeur des hydrocarbures. II. Toluène (with L. Constantinescu), DMP, 1, 157-161 (1940); Die Townsend'schen Ionisierungszahlen im Benzoldampf (with Margareta Valeriu), BSRP, 42, 3-21 (1941); Die Townsend'schen Ionisationskoeffizienten in einigen Kohlenwasserstoffdämpfen (with Margareta Valeriu), BSRP, 43, 3-8 (1942); On the electron emission from the cathode of electrical discharges in gases, V. Adamachi Sci. Review, 28, Nr.1, 3-15 (1942); Die Townsend'schen Ionisationskoeffizienten in Hg Dampf (with G. G. Bratescu), BSRP, 44, 1 (1943); Déterminations des coefficients Townsend dans la vapeur de mercure (with G. G. Bratescu), BRPS, 45, 9-25 (1944). Outstanding contributions brought Radu Grigorovici to the study of electrical breakdown of mercury vapours and Radu Grigorovici and Gheorghe Cristescu to the study of the high frequency torch: Über die Zündspannung in Quecksilberdampf (R. Grigorovici), BSRP, 38, 7-15 (1937); Die Zündspannung von reinem Quecksilberdampf (R. Grigorovici), ZP, 111, 596-616 (1939); Temperaturbestimmungen an einer hochfrequenten Fackelentladung aus der Intensitätsverteilung in N2 und OH Banden, sowie durch Linienumkehr (R. Grigorovici and G. Cristescu), BSRP, 42, 37-51 (1941); Optische Temperaturbestimmungen an der hochfrequenten Fackelentladung (R. Grigorovici and G. Cristescu), Naturwissenschaften, 29, 571-572 (1941); Untersuchungen über die Hochfrequenz-Fackelentladung (R. Grigorovici and G. Cristescu), RRP, 1, 103-126 (1956); K teorii visokociastotnovo fakel'novo razriada (R. Grigorovici and G. Cristescu), Optika i Spektroskopia, 6, 129-136 (1959). Citations:Th. Rummel, Hochspannungs - Entladungschemie und ihre industrielle Anwendungen, München, p. 63 (1951); J. Meek si J. Craggs, Electrical Breakdown of Gases, Oxford, pp. 54, 78 (1953); A. von Engel, Ionization in Gases by Electrons in Electric Fields, Encyclopedia of Physics, XXI, 1956, Fig. 25 (p. 531), Fig. 37 (p. 537), Tables 2 and 3 (p. 539); P. F. Little, Secondary Effects, Encyclopedia of Physics, XXI, 1956, Fig. 7 (p. 595), Fig. 11 (p.599); A. von Engel, Ionized Gases, Oxford, 1955, Table 22 and Fig. 92; S. C. Brown, Basic Data of Plasma Physics, Massachusetts, 1959, Fig. 4.39 (p. 129), Fig. 4.47 (p. 133), Fig. 11.27 (p. 237), Fig. 11.31 (p.239); N. A. Kaptzow, Electrical phenomena in gases and vacuum (Technical Publ. House, Bucharest).

The Second Bucharest Period (1945-1975)

As professor of the Bucharest University (1935-1962, consulting professor from 1964), first at the Faculty of Sciences, then re-organized as the Faculty of Mathematics and Physics, within essentially the same chair covering finally the disciplines of Optics, Spectroscopy, Plasma, and (presently) Lasers, and as founding director of the Institute of Physics at Bucharest of the Romanian Academy (1956-1970), Eugen Badareu resumed and amplified his researches, interrupted by the war, concerning the electrical discharges in gases and plasma physics. Among his co-workers from the previous period new ones will be added, many of them obtaining the doctor degree in physics under his scientific leadership. The publication production of his school becomes soon impressive, as it results from the following listing: On the electron energy losses in mercury vapours, SBRA, 1, Nr.8, 1-7 (1949); Some considerations regarding the electron emission from the cathode of electrical discharges in gases, SBRA, 3, Nr.4, 527-532 (1951); Über den Mechanismus der Elektronenemission aus der Kathode in Glimmentladungen, RRP, 1, 1-13 (1956); Über die Zündspannung und den Townsendschen Koeffizienten in Methan (with F. Wächter), RRP, 1, 161-165 (1956); Hochfrequente Fackelentladung als Spektralquelle (with Margareta Giurgea, G. Giurgea, and Ath. Trutia), Colloquium Spectroscopicum Internationale VI, Amsterdam 1956, Pergamon Press, London, 441-447 (1956). The major contributions of Prof. Eugen Badareu in Electrical Gas Discharges and Plasma Physics can be grouped together along the following research directions: (i)Positive ions kinetics in gases (1950-1959) with Mircea Hagiescu-Miriste: Hg+ ions energy losses in Hg vapours (with M. Hagiescu-Miriste), SBRA, 2, Nr.7, 603-609 (1950); On the positive ion kinetics in hydrogen (with M. Hagiescu-Miriste), GSSRA, 2-12 iunie 1950; Positive ions energy losses in hydrogen (with M. Hagiescu-Miriste), SRP, 2, 71-79 (1951); K+ ions energy losses in hydrogen and in Hg vapours (with M. Hagiescu-Miriste), RACP, 1, 763-767 (1951); On positive Helium and Potassium ions energy losses in Helium (with M. Hagiescu-Miriste), RACP, 3, 25-29 (1953); Sur la redistribution des vitesses des ions positifs Hg+ dans la vapeur de Hg à l'intérieur d'un espace équipotentiel (with M. Hagiescu-Miriste), RRP, 1, 189-198 (1956); Über die Kinetik der positiven Ionen an der Kathode einer Glimmentladung in Quecksilberdämpfen (with M. Hagiescu-Miriste), RRP, 4, 445-448 (1959). (ii) Glow discharges and hollow-cathode effect (1958-1968) with Ioan-Iovitz Popescu and Iancu Iova, Friedrich Wächter, Dumitru Ciobotaru, Constantin Popovici and Maria Somesan: Researches on the double cathode effect (with I.-Iovitz Popescu), JEC, 4, 503-514 (1958); The hollow cathode discharge in mercury vapour (with F. Wächter), JEC, 4, 539-543 (1958); Some problems regarding the phenomena occurring at the cathode of the glow discharge (with I.-Iovitz Popescu), RRP, 5, 41-82 (1960), with the Romanian version in SRP, 10, 689-732 (1959); Untersuchungen über den Mechanismus an der Kathode einer Glimmentladung (with I.-Iovitz Popescu), Proc. of the IVth ICPIG, Uppsala 17-21 August 1959, North Holland Publ. Co., Amsterdam, IIA, 301-305 (1960); Beiträge zur Klärung des Mechanismus des Doppelkathodeneffektes (with I.-Iovitz Popescu and I. Iova), AP, 5, 308-326 (1960); Vorgänge in den Kathodenteilen von anomalen Glimmentladungen in Helium (with I.-Iovitz Popescu and I. Iova), RRP, 5, 287-293 (1960), with the Romanian version in SRP, 11, Nr.3, 597-603 (1960); Über den Beitrag der Photonen zur Elektronenauslösung aus der Kathode in Glimmentladungen in Hg-Dämpfen (with F. Wächter), AP, 7, 418 (1961); Über die Elektronenauslösung durch Entladungsphotonen (with F. Wächter), Proc. of the V-th ICPIG, München, 1188 (1961); Über die Rolle der Resonanzumladung beim Mechanismus der anomalen Glimmentladung (with D. Ciobotaru), Proc. of the Symp. on Electron and Vacuum Physics, Hungary 1962, 489-496 (1962); Sur le transfer résonant de charge électrique dans les gaz monoatomiques (with D. Ciobotaru), Proc. of the VI-th ICPIG, Paris 1963, 97 (1963); Die Bestimmung der Umladungswirkungsquerschnittes bei der Glimmentladung in Neon und Xenon (with D. Ciobotaru), RRP, 8, 197-203 (1963); Hohlkathodeneffekt in Caesium Dampf (with C. Popovici, I. Iova and Maria Somesan), AP, 15, 313 (1965); Beiträge zum Studium des Mechanismus des Hohlkathodeneffektes (with C. Popovici and Maria Somesan), ZPC, 230, 90-105 (1965); On the beam instability in the negative glow plasma (with C. Popovici, Maria Somesan and Viorica Nistor), GSSRA, 1966; Glow-discharge to high-voltage-arc transition in argon-water vapour atmosphere (with Ath. Trutia and O. Zamfir), RRP, 11, 847 (1966); Contributions to the study of hollow cathode effect (with C. Popovici and Maria Somesan), RRP, 12, 3-11 (1967); On the amplification of the intensity of discharge current and radiation in hollow cathode discharges in magnetic field (with C. Popovici and Maria Somesan), Proc. of the VIII-th ICPIG, Vienna, 1967; Amplification of current and radiation intensities in the negative glow plasma of a hollow cathode discharge in magnetic field (with C. Popovici and Maria Somesan), RAL, Scienze Fisiche, Matematiche e Naturali, XIV, 245-248 (febb. 1968). (iii) Thermionic diodes and plasmas (1964-1965) with Ioan-Iovitz Popescu, Geavit Musa, Denisa Popescu, Constantin Ghita and Alexandra Baltog: Some data on cesium thermionic converters with mercury and xenon mixtures (with I.-Iovitz Popescu and O. Zamfir), JEC 16, 653-658 (1964); Investigations on the cesium-mercury diode (with I.-Iovitz Popescu, C.Ghita and O.Zamfir), BJAP, 15, 1171-1178 (1964); The influence of cathode geometry on the work of thermionic converters (with C. Popovici), JEC, 16, 537 (1964); Investigations on the cesium-cadmium diode (with I.-Iovitz Popescu, C.Ghita, G. Musa and O.Zamfir), BJAP, 16, 63-67 (1965); Atomic absorption by electron spectroscopy (with I.-Iovitz Popescu, C.Ghita and G. Musa), RRP, 10, 785-798 (1965); Atomic absorption of alkali vapours by the space charge amplification method (with I.-Iovitz Popescu, C.Ghita and G. Musa), Proc. of the VII-th ICPIG, Belgrade 1967, 372-376 (1965); Investigations on the caesium thermionic converter with an auxiliary discharge (with G. Musa and Denisa Popescu), BJAP, 16, 845 (1965); A caesium-noble gas filled thermionic diode with auxiliary discharge, (with G. Musa, Denisa Popescu and Alexandra Baltog), Proc. of the VII-th ICPIG, Belgrade 1967; Evidence of Rb-Cd second kind collision by space charge amplification (with G. Musa and Zinca Maris), Electronics Letters, 1, 26 (March 1965); (iv) Plasmachemistry researches (1959-1962) with Constantin Popovici and Dumitru Stefanescu: High frequency discharge action on butane (with D. Stefanescu and C. Popovici), RACP, 9, Nr.11, 1141-1146 (1959); On the glow discharge in butane-bromine mixture (with C. Popovici), RACP, 9, Nr.12, 1249-1256 (1959); Einwirkung der Hochfrequenzentladung auf Butan (with D. Stefanescu and C. Popovici), RRP, 5, 277-285 (1960); Contribution à l'étude des décharges à haute frequence dans le methane (with D. Stefanescu and C. Popovici), RRP, 4, Nr.1 (1960); Spectral data regarding the methane transformation under the action of the high frequency discharge (with C. Popovici), SRP, 11, Nr.3, (1960); On glow discharges in a butane-bromine mixture (with C. Popovici), RRP, 6, Nr.1 (1961); Über die Hochfrequenzentladung in Methan (with C. Popovici), Proc. of the Symp. on Electron and Vacuum Physics, Hungary 1962, 451-455 (1962); Beiträge zum Studium der Oxidation des Methans in der Funkenentladung (with C. Albu and C. Popovici), ZPC, 221 (1962). We add in this context the further contributions brought by the disciples of Prof. E. Badareu, mainly by Denisa Popescu and Ioan-Iovitz Popescu, by their pioneering works on optogalvanic and laser spectroscopy (1966-1981): Investigation on the thermionic detection of photoionization spectra of caesium vapours, AP, 18, 103 (1966); Absorptionsspektroskopie angeregter Caesium-Atome, ZP, 226, 160 (1969); Use of space charge techniques in the absorption spectroscopy of cesium atoms and molecules, PR, 8A, 1666-1672 (1973); Multiphoton ionization of molecular cesium with a tuneable dye laser,PR, 8A, 2197-2201 (1973); Multiphoton excitation and ionization of atomic cesium with a tuneable dye laser, PR, 9A, 1182-1187 (1974); Multiphoton ionization of cesium through resonant dissociative molecular states, PR, 10A, 813-821 (1974); Doublet line-strength ratios for the principal series of cesium,PR, 12A, 1425-1431 (1975); Fine-structure measurements of two-photon transitions in atomic cesium with a tuneable dye laser, OC, 16, 251-255 (1976); Multiphoton ionization of rubidium, PR, 14A, 1662-1671 (1976); Optical impedance spectroscopy, APL, 37, 888-890 (1980); Two-photon technique for the dissociative spectroscopy of simple molecules, PRL, 44, 139-142 (1980); Photolytic spectroscopy of simple molecules, Parts I, II, and III, JCP, 74, 1053-1066 (1981); 74, 1067-1073 (1981); 75, 4852 (1981). Citations: several hundreds of foreign citations, among we notice those of well-known scientists such as A. von Engel, K. G. Emeléus, J.-L. Delcroix, C. B. Collins, J. B. Hasted, G. Ecker, H. Walther, W. Demtröder, L. A. Sena, Y. M. Kagan, J. Richter, N. B. Delone, K. Niemax, P. Camus, G. Schaefer, E. Hansche, K. G. Müller, B. I. Moskalev, A. Ricard, and many others.

Even if the major weight of his scientific work belongs to the field of electrical discharges in gases and plasma physics, Eugen Badareu has important contributions also in other fields of physics, such as his researches in solid state physics with Paul Petrescu, Vladimir Topa and Trutia Athanasie: Exoelectronic emission phenomena (with P. Petrescu), SRP, 10, Nr.1, 187-192 (1959); Contribution to the induced photoelectric effect (with P. Petrescu), RACP, 10, 85-91 (1960); Spectrophotometric study of the colour centers obtained by different methods in alkalihalides (with Athanasie Trutia and Vladimir Topa), RRP, 9, 631 (1964). Also, besides his constant interest for basic researches, Eugen Badareu had always a permanent concern for science applications. In this respect, we remind herewith his researches regarding the multiple applications of the glow discharges, such as those on the cold cathode fluorescent tubes (with C. Popovici and E. Lucatu, 1955-1960) and on the cold cathode diodes and triodes (with G. Musa, 1964), as well as his series of paper dedicated to applied acoustics and ultraacoustics (1950-1967, with Mircea Grumazescu and Gheorghe Giurgea): Researches regarding the ultrasound influence on plants germination and growth (with G. Giurgea), SBRA, 2, Nr.8, 1-5 (1950); Quelques recherches, sur les maquettes, au sujet de la non-uniformité du champ sonore dans les éspaces clos (with G. Giurgea and M. Grumazescu), RRP, 2, Nr.1, 15-32 (1957); Room wall inclination influence on the sonic field uniformity (with G. Giurgea and M. Grumazescu), RACP, 8, Nr.3, 263-268 (1958); On a space non-uniformity index of the sonic field (with G. Giurgea and M. Grumazescu), RACP, 8, Nr.5, 461-466 (1958); Wall absorption influence on the sonic field uniformity (with G. Giurgea and M. Grumazescu), SRP, 10, Nr.3, 435-441 (1959); Measuring conditions of sonic absorption coefficients in a diffuse field (with M. Grumazescu), SRP, 10, Nr.4, 617-625 (1959).
 


TEXTBOOKS AND BOOKS

Printed textbooks at the University of Cernauti: Mechanics of Solids (1922), Molecular Physics (1922), Theory of Electricity (1922), Electricity (1924), Elements of Vector Calculus (1925), Electronics and Radioactivity (1925).

Printed textbooks at the University of Bucharest: Acoustics and Optics, 543 pages (1935), Acoustics, 213 pages (1945), Acoustics, 328 pages (1947), Wave Optics, 216 pages (1948).

Printed books: Cinematography, Bucharest, National Publ. House Gh. Mecu, 160 pages (1942), Introduction to Acoustics, Bucharest, Academy Publ. House, 284 pages (1953), Ultraacoustics and Applications, Bucharest, Academy Publ. House, (1957), Physics of Electrical Discharges in Gases, Bucharest, Academy Publ. House, 301 pages (1957), Fundamentals of Modern Acoustics (with M. Grumazescu), Bucharest, Academy Publ. House, 508 pages (1961), Ionized Gases - Basic Processes (with Ioan-Iovitz Popescu), Bucharest, Technical Publ. House, 351 pages (1963), Ionized Gases - Electrical Discharges in Gases (with Ioan-Iovitz Popescu), Bucharest, Technical Publ. House, 323 pages (1965), Physical and Technical Ultraacoustics (with M. Grumazescu), Bucharest, Technical Publ. House, 316 pages (1967), and Gaz Ionisés, Décharges Électriques dans les Gaz (with Ioan-Iovitz Popescu), Publ. Houses Dunod, Paris, and Meridiane, Bucharest, 333 pages (1968), that became a reference book on electrical gas discharges in French speaking countries.
 


INTERNATIONAL RELATIONSHIPS

Eugen Badareu had many relations with reputed scientists from abroad. Further, we shall mention only those personalities, well-known in electrical gas discharges and plasma physics, and which were in friendship relations with Eugen Badareu such as Rudolf Seeliger (University of Greifswald), Leonard B. Loeb (University of California, Berkeley), Alfred von Engel (University of Oxford), George Emeléus (University of Belfast), Jean-Loup Delcroix (University of Paris-Sud), Walter Lochte-Holtgreven (University of Kiel), Manfred A. Biondi (University of Pittsburgh), Carl B. Collins (University of Texas at Dallas), Jaap Kistemaker (Institute of Atomic and Molecular Physics in Amsterdam), Matvey Samsonovich Rabinovich (Lebedev Institute of Physics of the Academy of Science in Moscow), Hans A. Bertele (Polytechnic in Vienna), Brana Perovici (Institute of Nuclear Sciences in Belgrade), Ludek Pekárek (Institute of Physics of the Academy of Sciences in Prague) and many others. In the summer of 1969, under the Eugen Badareuí presidency, was organized at Bucharest the IX-th International Conference on Phenomena in Ionized Gases, 1-6 September, 1969, the greatest and most prestigious scientific meeting occurring until in Romania, with about 800 participants coming from 32 countries. At that moment, as a supreme homage brought to Eugen Badareu for his 82 years anniversary, almost all the world-wide active elite in his favourite research field has been present around him.

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